Version v0.3.50 - Fixing browsing behavior

.gitignore

@@ -24,3 +24,10 @@ test_truerng
 # Temporary files
 *.pad
 *.state
+
+# Downloaded dependencies (source)
+miniz/
+microtar/
+
+# Test directories
+test_dir/

Makefile

@@ -1,25 +1,40 @@
 CC = gcc
-CFLAGS = -Wall -Wextra -std=c99 -Isrc
+CFLAGS = -Wall -Wextra -std=c99 -Isrc -Iminiz -Imicrotar/src
+CFLAGS_MINIZ = -Wall -Wextra -std=c99 -D_POSIX_C_SOURCE=200112L -Isrc -Iminiz -Imicrotar/src -Wno-unused-function -Wno-implicit-function-declaration
 LIBS = -lm
 LIBS_STATIC = -static -lm
 ARCH = $(shell uname -m)
 TARGET = build/otp-$(ARCH)
 SOURCES = $(wildcard src/*.c)
+MINIZ_SOURCES = $(wildcard miniz/*.c)
+MICROTAR_SOURCES = $(wildcard microtar/src/*.c)
 OBJS = $(SOURCES:.c=.o)
+MINIZ_OBJS = $(MINIZ_SOURCES:.c=.o)
+MICROTAR_OBJS = $(MICROTAR_SOURCES:.c=.o)
+ALL_OBJS = $(OBJS) $(MINIZ_OBJS) $(MICROTAR_OBJS)
 
 # Default build target
-$(TARGET): $(OBJS)
+$(TARGET): $(ALL_OBJS)
 	@mkdir -p build
-	$(CC) $(CFLAGS) -o $(TARGET) $(OBJS) $(LIBS)
+	$(CC) $(CFLAGS) -o $(TARGET) $(ALL_OBJS) $(LIBS)
-	@rm -f $(OBJS)
+	@rm -f $(ALL_OBJS)
 
 # Static linking target
-static: $(OBJS)
+static: $(ALL_OBJS)
 	@mkdir -p build
-	$(CC) $(CFLAGS) -o $(TARGET) $(OBJS) $(LIBS_STATIC)
+	$(CC) $(CFLAGS) -o $(TARGET) $(ALL_OBJS) $(LIBS_STATIC)
-	@rm -f $(OBJS)
+	@rm -f $(ALL_OBJS)
 
-%.o: %.c
+# Compile main source files with full warnings
+src/%.o: src/%.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+# Compile miniz library files with reduced warnings
+miniz/%.o: miniz/%.c
+	$(CC) $(CFLAGS_MINIZ) -c $< -o $@
+
+# Compile microtar library files normally
+microtar/src/%.o: microtar/src/%.c
 	$(CC) $(CFLAGS) -c $< -o $@
 
 clean:

README.md

@@ -43,6 +43,7 @@ One-time pads can be trivially encrypted and decrypted using pencil and paper, m
 ## Features
 
 - **Perfect Security**: Implements true one-time pad encryption with information-theoretic security
+- **Traffic Analysis Resistance**: Exponential bucketing with ISO/IEC 9797-1 Method 2 (Padmé) padding hides message lengths
 - **Text & File Encryption**: Supports both inline text and file encryption
 - **Multiple Output Formats**: Binary (.otp) and ASCII armored (.otp.asc) file formats
 - **Hardware RNG Support**: Direct entropy collection from TrueRNG USB devices with automatic detection
@@ -58,14 +59,14 @@ One-time pads can be trivially encrypted and decrypted using pencil and paper, m
 
 ### Download Pre-Built Binaries
 
-**[Download Current Linux x86](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.34/otp-v0.3.34-linux-x86_64)**
+**[Download Current Linux x86](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.49/otp-v0.3.49-linux-x86_64)**
 
-**[Download Current Raspberry Pi 64](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.34/otp-v0.3.34-linux-arm64)**
+**[Download Current Raspberry Pi 64](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.49/otp-v0.3.49-linux-arm64)**
 
 After downloading:
 ```bash
 # Rename for convenience, then make executable
-mv otp-v0.3.34-linux-x86_64 otp
+mv otp-v0.3.49-linux-x86_64 otp
 chmod +x otp
 
 # Run it
@@ -189,8 +190,23 @@ git tag v1.0.0    # Next build: v1.0.1
 - Custom 256-bit XOR checksum for pad identification (encrypted with pad data)
 - Read-only pad files to prevent accidental modification
 - State tracking to prevent pad reuse
+- **Message Length Hiding**: Exponential bucketing (256B, 512B, 1KB, 2KB, 4KB...) prevents traffic analysis
+- **ISO/IEC 9797-1 Method 2 Padding**: Standard-compliant Padmé padding with 0x80 marker
 - **Zero external crypto dependencies** - completely self-contained implementation
 
+### Message Padding
+
+All encrypted messages and files are automatically padded using exponential bucketing to resist traffic analysis attacks:
+
+- **Minimum size**: 256 bytes
+- **Bucket sizes**: 256B → 512B → 1KB → 2KB → 4KB → 8KB → ...
+- **Padding method**: ISO/IEC 9797-1 Method 2 (Padmé padding)
+  - Appends `0x80` byte after message
+  - Fills remaining space with `0x00` bytes
+  - Unambiguous padding removal during decryption
+
+**Example**: A 10-byte message is padded to 256 bytes, while a 300-byte message is padded to 512 bytes. This provides strong protection for small messages where length leakage matters most, with logarithmic overhead for larger messages.
+
 ## Project Structure
 
 ```
@@ -205,6 +221,7 @@ otp/
 │   ├── ui.c             # Interactive user interface and menu system
 │   ├── state.c          # Global state management (pads directory, preferences)
 │   ├── crypto.c         # Core cryptographic operations (XOR, base64)
+│   ├── padding.c        # Message padding (exponential bucketing, Padmé padding)
 │   ├── pads.c           # Pad management and file operations
 │   ├── entropy.c        # Entropy collection from various sources
 │   ├── trng.c           # Hardware RNG device detection and collection
@@ -217,6 +234,7 @@ otp/
 ├── pads/                # OTP pad storage directory (created at runtime)
 ├── files/               # Encrypted file storage (created at runtime)
 └── tests/               # Test scripts and utilities
+    └── test_padding.sh  # Padding implementation tests
 ```
 
 ## Architecture
@@ -227,6 +245,7 @@ The OTP cipher uses a modular architecture with clean separation of concerns:
 - **ui.c**: Interactive user interface, menus, and terminal management
 - **state.c**: Global state management (pads directory, terminal dimensions, preferences)
 - **crypto.c**: Core cryptographic operations (XOR encryption, base64 encoding)
+- **padding.c**: Message padding implementation (exponential bucketing, ISO/IEC 9797-1 Method 2)
 - **pads.c**: Pad file management, checksums, and state tracking
 - **entropy.c**: Entropy collection from keyboard, dice, files, and hardware RNG
 - **trng.c**: Hardware RNG device detection and entropy collection from USB devices
@@ -431,6 +450,28 @@ No.  ChkSum (first 16 chars) Size         Used         % Used
 # Select "S" for show pad info, enter checksum or prefix
 ```
 
+## Important Notes
+
+### Size Units: Decimal (SI) vs Binary (IEC)
+
+**This program uses decimal (SI) units for all size specifications**, matching the behavior of most system tools like `ls -lh`, `df -h`, and file managers:
+
+- **1 KB** = 1,000 bytes (not 1,024)
+- **1 MB** = 1,000,000 bytes (not 1,048,576)
+- **1 GB** = 1,000,000,000 bytes (not 1,073,741,824)
+- **1 TB** = 1,000,000,000,000 bytes (not 1,099,511,627,776)
+
+**Why decimal units?**
+- Consistency with system tools (`ls`, `df`, file managers)
+- Matches storage device marketing (a "1TB" USB drive has ~1,000,000,000,000 bytes)
+- Avoids confusion when comparing sizes across different tools
+- Industry standard for storage devices and file systems
+
+**Example:** When you request a 100GB pad, the program creates exactly 100,000,000,000 bytes, which will display as "100GB" in `ls -lh` and your file manager.
+
+**Note:** Some technical tools may use binary units (GiB, MiB) where 1 GiB = 1,024³ bytes. This program intentionally uses decimal units for user-friendliness and consistency with common tools.
+
+
 ## License
 
 This project includes automatic versioning system based on the Generic Automatic Version Increment System.

build.sh

@@ -346,10 +346,29 @@ clean_project() {
 }
 
 install_project() {
-    print_status "Installing OTP project..."
+    print_status "Building project before installation..."
+    
+    # Build the project first (without version increment for install)
+    print_status "Cleaning previous build..."
+    make clean
+    
+    print_status "Building OTP project for x86_64..."
+    make CC=gcc ARCH=x86_64
+    if [ $? -ne 0 ]; then
+        print_error "Build failed"
+        return 1
+    fi
+    print_success "Build completed successfully"
+    
+    # Clean up object files after successful build
+    print_status "Cleaning up object files..."
+    rm -f src/*.o miniz/*.o microtar/src/*.o
+    
+    # Now install
+    print_status "Installing OTP project to system..."
     make install
     if [ $? -eq 0 ]; then
-        print_success "Installation completed"
+        print_success "Installation completed - binary installed to /usr/local/bin/otp"
     else
         print_error "Installation failed"
         return 1

otp

@@ -1 +0,0 @@
-./build/otp-x86_64

src/archive.c

@@ -0,0 +1,504 @@
+#define _POSIX_C_SOURCE 200809L
+#define _DEFAULT_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <dirent.h>
+#include <time.h>
+#include "main.h"
+#include "microtar.h"
+
+// Suppress warnings from miniz header
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-function"
+#include "miniz.h"
+#pragma GCC diagnostic pop
+
+////////////////////////////////////////////////////////////////////////////////
+//      DIRECTORY ARCHIVING FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+// Helper function to recursively add directory contents to TAR archive
+static int add_directory_to_tar(mtar_t* tar, const char* base_path, const char* relative_path) {
+    DIR* dir = opendir(base_path);
+    if (!dir) {
+        printf("Error: Cannot open directory '%s'\n", base_path);
+        return 1;
+    }
+
+    struct dirent* entry;
+    while ((entry = readdir(dir)) != NULL) {
+        // Skip . and ..
+        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
+            continue;
+        }
+
+        // Build full path
+        char full_path[2048];
+        snprintf(full_path, sizeof(full_path), "%s/%s", base_path, entry->d_name);
+
+        // Build relative path for TAR
+        char tar_path[2048];
+        if (strlen(relative_path) > 0) {
+            snprintf(tar_path, sizeof(tar_path), "%s/%s", relative_path, entry->d_name);
+        } else {
+            snprintf(tar_path, sizeof(tar_path), "%s", entry->d_name);
+        }
+
+        struct stat st;
+        if (stat(full_path, &st) != 0) {
+            printf("Warning: Cannot stat '%s', skipping\n", full_path);
+            continue;
+        }
+
+        if (S_ISDIR(st.st_mode)) {
+            // Recursively add subdirectory
+            if (add_directory_to_tar(tar, full_path, tar_path) != 0) {
+                closedir(dir);
+                return 1;
+            }
+        } else if (S_ISREG(st.st_mode)) {
+            // Add regular file
+            FILE* fp = fopen(full_path, "rb");
+            if (!fp) {
+                printf("Warning: Cannot open '%s', skipping\n", full_path);
+                continue;
+            }
+
+            // Get file size
+            fseek(fp, 0, SEEK_END);
+            size_t file_size = ftell(fp);
+            fseek(fp, 0, SEEK_SET);
+
+            // Read file data
+            unsigned char* file_data = malloc(file_size);
+            if (!file_data) {
+                printf("Error: Memory allocation failed for '%s'\n", full_path);
+                fclose(fp);
+                closedir(dir);
+                return 1;
+            }
+
+            size_t bytes_read = fread(file_data, 1, file_size, fp);
+            fclose(fp);
+
+            if (bytes_read != file_size) {
+                printf("Warning: Could not read entire file '%s', skipping\n", full_path);
+                free(file_data);
+                continue;
+            }
+
+            // Write to TAR
+            if (mtar_write_file_header(tar, tar_path, file_size) != MTAR_ESUCCESS) {
+                printf("Error: Failed to write TAR header for '%s'\n", tar_path);
+                free(file_data);
+                closedir(dir);
+                return 1;
+            }
+
+            if (mtar_write_data(tar, file_data, file_size) != MTAR_ESUCCESS) {
+                printf("Error: Failed to write TAR data for '%s'\n", tar_path);
+                free(file_data);
+                closedir(dir);
+                return 1;
+            }
+
+            free(file_data);
+        }
+    }
+
+    closedir(dir);
+    return 0;
+}
+
+// Create TAR archive from directory
+int create_tar_archive(const char* dir_path, const char* tar_output_path) {
+    mtar_t tar;
+    
+    if (mtar_open(&tar, tar_output_path, "w") != MTAR_ESUCCESS) {
+        printf("Error: Cannot create TAR file '%s'\n", tar_output_path);
+        return 1;
+    }
+
+    // Get directory name for relative paths
+    char dir_name[512];
+    const char* last_slash = strrchr(dir_path, '/');
+    if (last_slash) {
+        strncpy(dir_name, last_slash + 1, sizeof(dir_name) - 1);
+    } else {
+        strncpy(dir_name, dir_path, sizeof(dir_name) - 1);
+    }
+    dir_name[sizeof(dir_name) - 1] = '\0';
+
+    // Add directory contents to TAR
+    int result = add_directory_to_tar(&tar, dir_path, dir_name);
+
+    // Finalize and close TAR
+    mtar_finalize(&tar);
+    mtar_close(&tar);
+
+    return result;
+}
+
+// Extract TAR archive to directory
+int extract_tar_archive(const char* tar_path, const char* output_dir) {
+    mtar_t tar;
+    mtar_header_t header;
+
+    if (mtar_open(&tar, tar_path, "r") != MTAR_ESUCCESS) {
+        printf("Error: Cannot open TAR file '%s'\n", tar_path);
+        return 1;
+    }
+
+    // Create output directory if it doesn't exist
+    mkdir(output_dir, 0755);
+
+    // Extract each file
+    while (mtar_read_header(&tar, &header) == MTAR_ESUCCESS) {
+        char output_path[2048];
+        snprintf(output_path, sizeof(output_path), "%s/%s", output_dir, header.name);
+
+        // Create parent directories
+        char* last_slash = strrchr(output_path, '/');
+        if (last_slash) {
+            char parent_dir[2048];
+            strncpy(parent_dir, output_path, last_slash - output_path);
+            parent_dir[last_slash - output_path] = '\0';
+            
+            // Create directories recursively
+            char* p = parent_dir;
+            while (*p) {
+                if (*p == '/') {
+                    *p = '\0';
+                    mkdir(parent_dir, 0755);
+                    *p = '/';
+                }
+                p++;
+            }
+            mkdir(parent_dir, 0755);
+        }
+
+        // Extract file data
+        unsigned char* data = malloc(header.size);
+        if (!data) {
+            printf("Error: Memory allocation failed\n");
+            mtar_close(&tar);
+            return 1;
+        }
+
+        if (mtar_read_data(&tar, data, header.size) != MTAR_ESUCCESS) {
+            printf("Error: Failed to read data for '%s'\n", header.name);
+            free(data);
+            mtar_close(&tar);
+            return 1;
+        }
+
+        // Write to file
+        FILE* fp = fopen(output_path, "wb");
+        if (!fp) {
+            printf("Error: Cannot create file '%s'\n", output_path);
+            free(data);
+            mtar_close(&tar);
+            return 1;
+        }
+
+        fwrite(data, 1, header.size, fp);
+        fclose(fp);
+        free(data);
+
+        mtar_next(&tar);
+    }
+
+    mtar_close(&tar);
+    return 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//      COMPRESSION FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+// Compress file with gzip (miniz)
+int compress_file_gzip(const char* input_path, const char* output_path) {
+    // Read input file
+    FILE* in = fopen(input_path, "rb");
+    if (!in) {
+        printf("Error: Cannot open input file '%s'\n", input_path);
+        return 1;
+    }
+
+    fseek(in, 0, SEEK_END);
+    size_t input_size = ftell(in);
+    fseek(in, 0, SEEK_SET);
+
+    unsigned char* input_data = malloc(input_size);
+    if (!input_data) {
+        printf("Error: Memory allocation failed\n");
+        fclose(in);
+        return 1;
+    }
+
+    size_t bytes_read = fread(input_data, 1, input_size, in);
+    fclose(in);
+
+    if (bytes_read != input_size) {
+        printf("Error: Failed to read input file\n");
+        free(input_data);
+        return 1;
+    }
+
+    // Compress with miniz
+    mz_ulong compressed_size = compressBound(input_size);
+    unsigned char* compressed_data = malloc(compressed_size);
+    if (!compressed_data) {
+        printf("Error: Memory allocation failed\n");
+        free(input_data);
+        return 1;
+    }
+
+    int result = compress2(compressed_data, &compressed_size,
+                          input_data, input_size,
+                          MZ_BEST_COMPRESSION);
+
+    free(input_data);
+
+    if (result != MZ_OK) {
+        printf("Error: Compression failed (error code: %d)\n", result);
+        free(compressed_data);
+        return 1;
+    }
+
+    // Write compressed data
+    FILE* out = fopen(output_path, "wb");
+    if (!out) {
+        printf("Error: Cannot create output file '%s'\n", output_path);
+        free(compressed_data);
+        return 1;
+    }
+
+    fwrite(compressed_data, 1, compressed_size, out);
+    fclose(out);
+    free(compressed_data);
+
+    return 0;
+}
+
+// Decompress gzip file (miniz)
+int decompress_file_gzip(const char* input_path, const char* output_path) {
+    // Read compressed file
+    FILE* in = fopen(input_path, "rb");
+    if (!in) {
+        printf("Error: Cannot open compressed file '%s'\n", input_path);
+        return 1;
+    }
+
+    fseek(in, 0, SEEK_END);
+    size_t compressed_size = ftell(in);
+    fseek(in, 0, SEEK_SET);
+
+    unsigned char* compressed_data = malloc(compressed_size);
+    if (!compressed_data) {
+        printf("Error: Memory allocation failed\n");
+        fclose(in);
+        return 1;
+    }
+
+    size_t bytes_read = fread(compressed_data, 1, compressed_size, in);
+    fclose(in);
+
+    if (bytes_read != compressed_size) {
+        printf("Error: Failed to read compressed file\n");
+        free(compressed_data);
+        return 1;
+    }
+
+    // Estimate decompressed size (try multiple times if needed)
+    mz_ulong output_size = compressed_size * 10;
+    unsigned char* output_data = NULL;
+    int result;
+
+    for (int attempt = 0; attempt < 3; attempt++) {
+        output_data = realloc(output_data, output_size);
+        if (!output_data) {
+            printf("Error: Memory allocation failed\n");
+            free(compressed_data);
+            return 1;
+        }
+
+        mz_ulong temp_size = output_size;
+        result = uncompress(output_data, &temp_size, compressed_data, compressed_size);
+
+        if (result == MZ_OK) {
+            output_size = temp_size;
+            break;
+        } else if (result == MZ_BUF_ERROR) {
+            // Buffer too small, try larger
+            output_size *= 2;
+        } else {
+            printf("Error: Decompression failed (error code: %d)\n", result);
+            free(compressed_data);
+            free(output_data);
+            return 1;
+        }
+    }
+
+    free(compressed_data);
+
+    if (result != MZ_OK) {
+        printf("Error: Decompression failed after multiple attempts\n");
+        free(output_data);
+        return 1;
+    }
+
+    // Write decompressed data
+    FILE* out = fopen(output_path, "wb");
+    if (!out) {
+        printf("Error: Cannot create output file '%s'\n", output_path);
+        free(output_data);
+        return 1;
+    }
+
+    fwrite(output_data, 1, output_size, out);
+    fclose(out);
+    free(output_data);
+
+    return 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+//      HIGH-LEVEL DIRECTORY ENCRYPTION/DECRYPTION
+////////////////////////////////////////////////////////////////////////////////
+
+// Encrypt directory: TAR → GZIP → Encrypt
+int encrypt_directory(const char* dir_path, const char* pad_identifier, const char* output_file) {
+    char temp_tar[512];
+    char temp_gz[512];
+    int result = 0;
+
+    // Generate temporary file paths
+    snprintf(temp_tar, sizeof(temp_tar), "/tmp/otp_tar_%d.tar", getpid());
+    snprintf(temp_gz, sizeof(temp_gz), "/tmp/otp_gz_%d.tar.gz", getpid());
+
+    printf("Creating TAR archive...\n");
+    if (create_tar_archive(dir_path, temp_tar) != 0) {
+        printf("Error: Failed to create TAR archive\n");
+        return 1;
+    }
+
+    printf("Compressing archive...\n");
+    if (compress_file_gzip(temp_tar, temp_gz) != 0) {
+        printf("Error: Failed to compress archive\n");
+        unlink(temp_tar);
+        return 1;
+    }
+
+    printf("Encrypting compressed archive...\n");
+    result = encrypt_file(pad_identifier, temp_gz, output_file, 0);
+
+    // Cleanup temporary files
+    unlink(temp_tar);
+    unlink(temp_gz);
+
+    if (result == 0) {
+        printf("Directory encrypted successfully: %s\n", output_file);
+    }
+
+    return result;
+}
+
+// Detect if file is a compressed TAR archive
+int is_compressed_tar_archive(const char* file_path) {
+    FILE* fp = fopen(file_path, "rb");
+    if (!fp) {
+        return 0;
+    }
+
+    unsigned char magic[512];
+    size_t bytes_read = fread(magic, 1, sizeof(magic), fp);
+    fclose(fp);
+
+    if (bytes_read < 2) {
+        return 0;
+    }
+
+    // Check for GZIP magic bytes (0x1f 0x8b)
+    if (magic[0] == 0x1f && magic[1] == 0x8b) {
+        return 1;
+    }
+
+    // Check for TAR magic ("ustar" at offset 257)
+    if (bytes_read >= 262 && memcmp(magic + 257, "ustar", 5) == 0) {
+        return 1;
+    }
+
+    return 0;
+}
+
+// Decrypt and extract directory: Decrypt → GUNZIP → Extract TAR
+int decrypt_and_extract_directory(const char* encrypted_file, const char* output_dir) {
+    char temp_decrypted[512];
+    char temp_tar[512];
+    int result = 0;
+
+    // Generate temporary file paths
+    snprintf(temp_decrypted, sizeof(temp_decrypted), "/tmp/otp_decrypt_%d", getpid());
+    snprintf(temp_tar, sizeof(temp_tar), "/tmp/otp_tar_%d.tar", getpid());
+
+    printf("Decrypting file...\n");
+    if (decrypt_file(encrypted_file, temp_decrypted) != 0) {
+        printf("Error: Failed to decrypt file\n");
+        return 1;
+    }
+
+    // Check if it's compressed
+    FILE* fp = fopen(temp_decrypted, "rb");
+    if (!fp) {
+        printf("Error: Cannot open decrypted file\n");
+        unlink(temp_decrypted);
+        return 1;
+    }
+
+    unsigned char magic[2];
+    fread(magic, 1, 2, fp);
+    fclose(fp);
+
+    if (magic[0] == 0x1f && magic[1] == 0x8b) {
+        // GZIP compressed
+        printf("Decompressing archive...\n");
+        if (decompress_file_gzip(temp_decrypted, temp_tar) != 0) {
+            printf("Error: Failed to decompress archive\n");
+            unlink(temp_decrypted);
+            return 1;
+        }
+        unlink(temp_decrypted);
+    } else {
+        // Not compressed, assume it's already TAR
+        printf("File is not compressed, using as TAR directly...\n");
+        if (rename(temp_decrypted, temp_tar) != 0) {
+            printf("Error: Failed to rename decrypted file to TAR file\n");
+            unlink(temp_decrypted);
+            return 1;
+        }
+    }
+
+    // Verify TAR file exists before extraction
+    if (access(temp_tar, F_OK) != 0) {
+        printf("Error: TAR file does not exist at '%s'\n", temp_tar);
+        return 1;
+    }
+
+    printf("Extracting archive...\n");
+    result = extract_tar_archive(temp_tar, output_dir);
+
+    // Cleanup
+    unlink(temp_tar);
+
+    if (result == 0) {
+        printf("Directory extracted successfully to: %s\n", output_dir);
+    }
+
+    return result;
+}

src/crypto.c

@@ -297,7 +297,6 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
     }
 
     char text_buffer[MAX_INPUT_SIZE];
-    char chksum_hex[MAX_HASH_LENGTH];
     uint64_t current_offset;
 
     char pad_path[MAX_HASH_LENGTH + 20];
@@ -327,12 +326,8 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
         }
     }
 
-    // Calculate XOR checksum of pad file
+    // Use pad_chksum directly - it's already the checksum from the filename
-    if (calculate_checksum(pad_path, chksum_hex) != 0) {
+    // No need to recalculate by reading the entire pad file
-        printf("Error: Cannot calculate pad checksum\n");
-        free(pad_chksum);
-        return 1;
-    }
 
     // Get input text - either from parameter or user input
     if (input_text != NULL) {
@@ -406,18 +401,40 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
         return 1;
     }
 
-    // Check if we have enough pad space
+    // Calculate chunk size for padding (exponential bucketing)
-    struct stat pad_stat;
+    size_t chunk_size = calculate_chunk_size(input_len);
-    if (stat(pad_path, &pad_stat) != 0) {
+    
-        printf("Error: Cannot get pad file size\n");
+    // Allocate buffer for padded message
+    unsigned char* padded_buffer = malloc(chunk_size);
+    if (!padded_buffer) {
+        printf("Error: Memory allocation failed\n");
         free(pad_chksum);
         return 1;
     }
     
-    if (current_offset + input_len > (uint64_t)pad_stat.st_size) {
+    // Copy message to buffer and apply padding
+    memcpy(padded_buffer, text_buffer, input_len);
+    if (apply_padme_padding(padded_buffer, input_len, chunk_size) != 0) {
+        printf("Error: Failed to apply padding\n");
+        free(padded_buffer);
+        free(pad_chksum);
+        return 1;
+    }
+
+    // Check if we have enough pad space (now using chunk_size instead of input_len)
+    struct stat pad_stat;
+    if (stat(pad_path, &pad_stat) != 0) {
+        printf("Error: Cannot get pad file size\n");
+        free(padded_buffer);
+        free(pad_chksum);
+        return 1;
+    }
+
+    if (current_offset + chunk_size > (uint64_t)pad_stat.st_size) {
         printf("Error: Not enough pad space remaining\n");
         printf("Need: %lu bytes, Available: %lu bytes\n",
-               input_len, (uint64_t)pad_stat.st_size - current_offset);
+               chunk_size, (uint64_t)pad_stat.st_size - current_offset);
+        free(padded_buffer);
         free(pad_chksum);
         return 1;
     }
@@ -437,37 +454,40 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
         return 1;
     }
 
-    unsigned char* pad_data = malloc(input_len);
+    unsigned char* pad_data = malloc(chunk_size);
-    if (fread(pad_data, 1, input_len, pad_file) != input_len) {
+    if (fread(pad_data, 1, chunk_size, pad_file) != chunk_size) {
         printf("Error: Cannot read pad data\n");
         free(pad_data);
         fclose(pad_file);
+        free(padded_buffer);
         free(pad_chksum);
         return 1;
     }
     fclose(pad_file);
 
-    // Use universal XOR operation for encryption
+    // Use universal XOR operation for encryption (now with padded data)
-    unsigned char* ciphertext = malloc(input_len);
+    unsigned char* ciphertext = malloc(chunk_size);
-    if (universal_xor_operation((const unsigned char*)text_buffer, input_len, pad_data, ciphertext) != 0) {
+    if (universal_xor_operation(padded_buffer, chunk_size, pad_data, ciphertext) != 0) {
         printf("Error: Encryption operation failed\n");
         free(pad_data);
         free(ciphertext);
+        free(padded_buffer);
         free(pad_chksum);
         return 1;
     }
 
-    // Update state offset
+    // Update state offset (now using chunk_size)
-    if (write_state_offset(pad_chksum, current_offset + input_len) != 0) {
+    if (write_state_offset(pad_chksum, current_offset + chunk_size) != 0) {
         printf("Warning: Failed to update state file\n");
     }
 
-    // Use universal ASCII armor generator
+    // Use universal ASCII armor generator (now with chunk_size)
     char* ascii_output;
-    if (generate_ascii_armor(chksum_hex, current_offset, ciphertext, input_len, &ascii_output) != 0) {
+    if (generate_ascii_armor(pad_chksum, current_offset, ciphertext, chunk_size, &ascii_output) != 0) {
         printf("Error: Failed to generate ASCII armor\n");
         free(pad_data);
         free(ciphertext);
+        free(padded_buffer);
         free(pad_chksum);
         return 1;
     }
@@ -484,6 +504,7 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
     // Cleanup
     free(pad_data);
     free(ciphertext);
+    free(padded_buffer);
     free(ascii_output);
     free(pad_chksum);
 
@@ -592,36 +613,14 @@ int universal_decrypt(const char* input_data, const char* output_target, decrypt
         return 1;
     }
 
-    // Validate pad integrity
+    // Pad integrity validation disabled for performance
-    int integrity_result = validate_pad_integrity(pad_path, stored_chksum);
+    // The checksum is already verified by matching the filename
-    if (integrity_result == 3) {
+    // If you need to verify pad integrity, the pad file would need to be read entirely
-        if (mode == DECRYPT_MODE_SILENT) {
+    // which is very slow for large pads (multi-GB files)
-            fprintf(stderr, "Error: Pad integrity check failed!\n");
-            return 1;
-        } else if (mode == DECRYPT_MODE_INTERACTIVE) {
-            printf("Warning: Pad integrity check failed!\n");
-            printf("Expected: %s\n", stored_chksum);
-            printf("Continue anyway? (y/N): ");
-            fflush(stdout);
     
-            char response[10];
+    // Skip integrity check - trust the filename checksum
-            if (fgets(response, sizeof(response), stdin) == NULL ||
-                (response[0] != 'y' && response[0] != 'Y')) {
-                printf("Decryption aborted.\n");
-                return 1;
-            }
-        }
-    } else if (integrity_result != 0) {
-        if (mode == DECRYPT_MODE_SILENT) {
-            fprintf(stderr, "Error: Cannot verify pad integrity\n");
-        } else {
-            printf("Error: Cannot verify pad integrity\n");
-        }
-        return 1;
-    } else {
     if (mode == DECRYPT_MODE_INTERACTIVE || mode == DECRYPT_MODE_FILE_TO_TEXT) {
-            printf("Pad integrity: VERIFIED\n");
+        printf("Using pad: %s\n", stored_chksum);
-        }
     }
 
     // Decode base64 ciphertext
@@ -659,6 +658,22 @@ int universal_decrypt(const char* input_data, const char* output_target, decrypt
         return 1;
     }
 
+    // Remove padding to get actual message
+    size_t actual_msg_len;
+    if (remove_padme_padding(ciphertext, ciphertext_len, &actual_msg_len) != 0) {
+        if (mode == DECRYPT_MODE_SILENT) {
+            fprintf(stderr, "Error: Invalid padding - message may be corrupted\n");
+        } else {
+            printf("Error: Invalid padding - message may be corrupted\n");
+        }
+        free(ciphertext);
+        free(pad_data);
+        return 1;
+    }
+    
+    // Update ciphertext_len to actual message length
+    ciphertext_len = actual_msg_len;
+
     // Output based on mode
     if (mode == DECRYPT_MODE_FILE_TO_FILE) {
         // Write to output file
@@ -746,7 +761,6 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         return 1;
     }
 
-    char chksum_hex[MAX_HASH_LENGTH];
     uint64_t current_offset;
 
     char pad_path[MAX_HASH_LENGTH + 20];
@@ -768,6 +782,9 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         return 1;
     }
 
+    // Calculate chunk size for padding (exponential bucketing)
+    size_t chunk_size = calculate_chunk_size(file_size);
+
     // Check if pad file exists
     if (access(pad_path, R_OK) != 0) {
         printf("Error: Pad file %s not found\n", pad_path);
@@ -791,12 +808,8 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         }
     }
 
-    // Calculate XOR checksum of pad file
+    // Use pad_chksum directly - it's already the checksum from the filename
-    if (calculate_checksum(pad_path, chksum_hex) != 0) {
+    // No need to recalculate by reading the entire pad file
-        printf("Error: Cannot calculate pad checksum\n");
-        free(pad_chksum);
-        return 1;
-    }
 
     // Check if we have enough pad space
     struct stat pad_stat;
@@ -806,10 +819,10 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         return 1;
     }
 
-    if (current_offset + file_size > (uint64_t)pad_stat.st_size) {
+    if (current_offset + chunk_size > (uint64_t)pad_stat.st_size) {
         printf("Error: Not enough pad space remaining\n");
-        printf("Need: %lu bytes, Available: %lu bytes\n",
+        printf("Need: %lu bytes (file: %lu + padding), Available: %lu bytes\n",
-               file_size, (uint64_t)pad_stat.st_size - current_offset);
+               chunk_size, file_size, (uint64_t)pad_stat.st_size - current_offset);
         free(pad_chksum);
         return 1;
     }
@@ -854,65 +867,92 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         return 1;
     }
 
-    // Read and encrypt file
+    // Allocate buffer for padded file data
-    unsigned char buffer[64 * 1024];
+    unsigned char* file_data = malloc(file_size);
-    unsigned char pad_buffer[64 * 1024];
+    if (!file_data) {
-    unsigned char* encrypted_data = malloc(file_size);
+        printf("Error: Memory allocation failed\n");
-    uint64_t bytes_processed = 0;
+        fclose(input_fp);
+        fclose(pad_file);
+        free(pad_chksum);
+        return 1;
+    }
 
     printf("Encrypting %s...\n", input_file);
 
-    while (bytes_processed < file_size) {
+    // Read entire file
-        uint64_t chunk_size = sizeof(buffer);
+    if (fread(file_data, 1, file_size, input_fp) != file_size) {
-        if (file_size - bytes_processed < chunk_size) {
+        printf("Error: Cannot read input file\n");
-            chunk_size = file_size - bytes_processed;
+        free(file_data);
+        fclose(input_fp);
+        fclose(pad_file);
+        free(pad_chksum);
+        return 1;
+    }
+    fclose(input_fp);
+
+    // Allocate buffer for padded data
+    unsigned char* padded_data = malloc(chunk_size);
+    if (!padded_data) {
+        printf("Error: Memory allocation failed\n");
+        free(file_data);
+        fclose(pad_file);
+        free(pad_chksum);
+        return 1;
     }
 
-        // Read file data
+    // Copy file data and apply padding
-        if (fread(buffer, 1, chunk_size, input_fp) != chunk_size) {
+    memcpy(padded_data, file_data, file_size);
-            printf("Error: Cannot read input file data\n");
+    free(file_data);
-            free(encrypted_data);
+    
-            fclose(input_fp);
+    if (apply_padme_padding(padded_data, file_size, chunk_size) != 0) {
+        printf("Error: Failed to apply padding\n");
+        free(padded_data);
         fclose(pad_file);
         free(pad_chksum);
         return 1;
     }
 
     // Read pad data
-        if (fread(pad_buffer, 1, chunk_size, pad_file) != chunk_size) {
+    unsigned char* pad_data = malloc(chunk_size);
+    if (!pad_data) {
+        printf("Error: Memory allocation failed\n");
+        free(padded_data);
+        fclose(pad_file);
+        free(pad_chksum);
+        return 1;
+    }
+
+    if (fread(pad_data, 1, chunk_size, pad_file) != chunk_size) {
         printf("Error: Cannot read pad data\n");
-            free(encrypted_data);
+        free(padded_data);
-            fclose(input_fp);
+        free(pad_data);
         fclose(pad_file);
         free(pad_chksum);
         return 1;
     }
+    fclose(pad_file);
 
-        // Use universal XOR operation for encryption
+    // Encrypt padded data
-        if (universal_xor_operation(buffer, chunk_size, pad_buffer, &encrypted_data[bytes_processed]) != 0) {
+    unsigned char* encrypted_data = malloc(chunk_size);
+    if (!encrypted_data) {
+        printf("Error: Memory allocation failed\n");
+        free(padded_data);
+        free(pad_data);
+        free(pad_chksum);
+        return 1;
+    }
+
+    if (universal_xor_operation(padded_data, chunk_size, pad_data, encrypted_data) != 0) {
         printf("Error: Encryption operation failed\n");
+        free(padded_data);
+        free(pad_data);
         free(encrypted_data);
-            fclose(input_fp);
-            fclose(pad_file);
         free(pad_chksum);
         return 1;
     }
 
-        bytes_processed += chunk_size;
+    free(padded_data);
-
+    free(pad_data);
-        // Show progress for large files (> 10MB)
-        if (file_size > 10 * 1024 * 1024 && bytes_processed % (1024 * 1024) == 0) {
-            // show_progress(bytes_processed, file_size, start_time); // MOVED TO src/util.c
-        }
-    }
-
-    if (file_size > 10 * 1024 * 1024) {
-        // show_progress(file_size, file_size, start_time); // MOVED TO src/util.c
-        printf("\n");
-    }
-
-    fclose(input_fp);
-    fclose(pad_file);
 
     // Write output file
     if (ascii_armor) {
@@ -925,9 +965,9 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
             return 1;
         }
 
-        // Use universal ASCII armor generator
+        // Use universal ASCII armor generator (now with chunk_size)
         char* ascii_output;
-        if (generate_ascii_armor(chksum_hex, current_offset, encrypted_data, file_size, &ascii_output) != 0) {
+        if (generate_ascii_armor(pad_chksum, current_offset, encrypted_data, chunk_size, &ascii_output) != 0) {
             printf("Error: Failed to generate ASCII armor\n");
             fclose(output_fp);
             free(encrypted_data);
@@ -961,7 +1001,7 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         // Pad checksum: 32 bytes (binary)
         unsigned char pad_chksum_bin[32];
         for (int i = 0; i < 32; i++) {
-            sscanf(chksum_hex + i*2, "%2hhx", &pad_chksum_bin[i]);
+            sscanf(pad_chksum + i*2, "%2hhx", &pad_chksum_bin[i]);
         }
         fwrite(pad_chksum_bin, 1, 32, output_fp);
 
@@ -973,17 +1013,17 @@ int encrypt_file(const char* pad_identifier, const char* input_file, const char*
         uint32_t file_mode = input_stat.st_mode;
         fwrite(&file_mode, sizeof(uint32_t), 1, output_fp);
 
-        // File size: 8 bytes
+        // File size: 8 bytes (original file size, not padded)
         fwrite(&file_size, sizeof(uint64_t), 1, output_fp);
 
-        // Encrypted data
+        // Encrypted data (padded)
-        fwrite(encrypted_data, 1, file_size, output_fp);
+        fwrite(encrypted_data, 1, chunk_size, output_fp);
 
         fclose(output_fp);
     }
 
-    // Update state offset
+    // Update state offset (now using chunk_size)
-    if (write_state_offset(pad_chksum, current_offset + file_size) != 0) {
+    if (write_state_offset(pad_chksum, current_offset + chunk_size) != 0) {
         printf("Warning: Failed to update state file\n");
     }
 
@@ -1044,14 +1084,14 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
     unsigned char pad_chksum_bin[32];
     uint64_t pad_offset;
     uint32_t file_mode;
-    uint64_t file_size;
+    uint64_t original_file_size;
 
     if (fread(magic, 1, 4, input_fp) != 4 ||
         fread(&version, sizeof(uint16_t), 1, input_fp) != 1 ||
         fread(pad_chksum_bin, 1, 32, input_fp) != 32 ||
         fread(&pad_offset, sizeof(uint64_t), 1, input_fp) != 1 ||
         fread(&file_mode, sizeof(uint32_t), 1, input_fp) != 1 ||
-        fread(&file_size, sizeof(uint64_t), 1, input_fp) != 1) {
+        fread(&original_file_size, sizeof(uint64_t), 1, input_fp) != 1) {
         printf("Error: Cannot read binary header\n");
         fclose(input_fp);
         return 1;
@@ -1071,7 +1111,7 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
     pad_chksum_hex[64] = '\0';
 
     printf("Decrypting binary file...\n");
-    printf("File size: %lu bytes\n", file_size);
+    printf("Original file size: %lu bytes\n", original_file_size);
 
     // Check if we have the required pad
     char pad_path[MAX_HASH_LENGTH + 20];
@@ -1096,9 +1136,18 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
         output_file = default_output;
     }
 
-    // Read encrypted data
+    // Calculate chunk size (encrypted data is padded)
-    unsigned char* encrypted_data = malloc(file_size);
+    size_t chunk_size = calculate_chunk_size(original_file_size);
-    if (fread(encrypted_data, 1, file_size, input_fp) != file_size) {
+
+    // Read encrypted (padded) data
+    unsigned char* encrypted_data = malloc(chunk_size);
+    if (!encrypted_data) {
+        printf("Error: Memory allocation failed\n");
+        fclose(input_fp);
+        return 1;
+    }
+
+    if (fread(encrypted_data, 1, chunk_size, input_fp) != chunk_size) {
         printf("Error: Cannot read encrypted data\n");
         free(encrypted_data);
         fclose(input_fp);
@@ -1121,8 +1170,15 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
         return 1;
     }
 
-    unsigned char* pad_data = malloc(file_size);
+    unsigned char* pad_data = malloc(chunk_size);
-    if (fread(pad_data, 1, file_size, pad_file) != file_size) {
+    if (!pad_data) {
+        printf("Error: Memory allocation failed\n");
+        free(encrypted_data);
+        fclose(pad_file);
+        return 1;
+    }
+
+    if (fread(pad_data, 1, chunk_size, pad_file) != chunk_size) {
         printf("Error: Cannot read pad data\n");
         free(encrypted_data);
         free(pad_data);
@@ -1132,26 +1188,40 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
     fclose(pad_file);
 
     // Use universal XOR operation for decryption
-    if (universal_xor_operation(encrypted_data, file_size, pad_data, encrypted_data) != 0) {
+    if (universal_xor_operation(encrypted_data, chunk_size, pad_data, encrypted_data) != 0) {
         printf("Error: Decryption operation failed\n");
         free(encrypted_data);
         free(pad_data);
         return 1;
     }
 
-    // Write decrypted file
+    free(pad_data);
+
+    // Remove padding to get original file
+    size_t actual_file_size;
+    if (remove_padme_padding(encrypted_data, chunk_size, &actual_file_size) != 0) {
+        printf("Error: Invalid padding - file may be corrupted\n");
+        free(encrypted_data);
+        return 1;
+    }
+
+    // Verify the actual size matches the stored original size
+    if (actual_file_size != original_file_size) {
+        printf("Warning: Decrypted size (%lu) doesn't match stored size (%lu)\n",
+               actual_file_size, original_file_size);
+    }
+
+    // Write decrypted file (using actual_file_size)
     FILE* output_fp = fopen(output_file, "wb");
     if (!output_fp) {
         printf("Error: Cannot create output file %s\n", output_file);
         free(encrypted_data);
-        free(pad_data);
         return 1;
     }
 
-    if (fwrite(encrypted_data, 1, file_size, output_fp) != file_size) {
+    if (fwrite(encrypted_data, 1, actual_file_size, output_fp) != actual_file_size) {
         printf("Error: Cannot write decrypted data\n");
         free(encrypted_data);
-        free(pad_data);
         fclose(output_fp);
         return 1;
     }
@@ -1165,12 +1235,14 @@ int decrypt_binary_file(FILE* input_fp, const char* output_file) {
     printf("File decrypted successfully: %s\n", output_file);
     printf("Restored permissions and metadata\n");
 
+    // Only pause if output is not a temporary file (directory decryption uses /tmp/)
+    if (strncmp(output_file, "/tmp/", 5) != 0) {
         // Pause before returning to menu to let user see the success message
         print_centered_header("File Decryption Complete", 1);
+    }
 
     // Cleanup
     free(encrypted_data);
-    free(pad_data);
 
     return 0;
 }

src/entropy.c

@@ -219,9 +219,23 @@ int add_entropy_chacha20(const char* pad_chksum, const unsigned char* entropy_da
     unsigned char buffer[64 * 1024]; // 64KB chunks
     unsigned char keystream[64 * 1024];
     uint64_t offset = 0;
-    uint32_t counter = 0;
+    uint32_t counter_low = 0;
+    uint32_t counter_high = 0;
     time_t start_time = time(NULL);
     
+    // Use extended counter for pads larger than 256GB
+    // 256GB = 2^32 blocks * 64 bytes = 274,877,906,944 bytes
+    int use_extended = (pad_size > 274877906944ULL);
+    
+    // For extended mode, use reduced 8-byte nonce
+    unsigned char nonce_reduced[8];
+    if (use_extended) {
+        memcpy(nonce_reduced, nonce + 4, 8);
+        if (display_progress) {
+            printf("Using extended counter mode for large pad (>256GB)\n");
+        }
+    }
+
     while (offset < pad_size) {
         size_t chunk_size = sizeof(buffer);
         if (pad_size - offset < chunk_size) {
@@ -237,7 +251,15 @@ int add_entropy_chacha20(const char* pad_chksum, const unsigned char* entropy_da
         }
 
         // Generate keystream for this chunk
-        if (chacha20_encrypt(key, counter, nonce, buffer, keystream, chunk_size) != 0) {
+        int chacha_result;
+        if (use_extended) {
+            chacha_result = chacha20_encrypt_extended(key, counter_low, counter_high,
+                                                      nonce_reduced, buffer, keystream, chunk_size);
+        } else {
+            chacha_result = chacha20_encrypt(key, counter_low, nonce, buffer, keystream, chunk_size);
+        }
+        
+        if (chacha_result != 0) {
             printf("Error: Chacha20 keystream generation failed\n");
             fclose(pad_file);
             chmod(pad_path, S_IRUSR);
@@ -265,7 +287,16 @@ int add_entropy_chacha20(const char* pad_chksum, const unsigned char* entropy_da
         }
 
         offset += chunk_size;
-        counter += (chunk_size + 63) / 64; // Round up for block count
+        
+        // Update counters
+        uint32_t blocks = (chunk_size + 63) / 64; // Round up for block count
+        uint32_t old_counter_low = counter_low;
+        counter_low += blocks;
+        
+        // Check for overflow and increment high counter
+        if (counter_low < old_counter_low) {
+            counter_high++;
+        }
 
         // Show progress for large pads
         if (display_progress && offset % (64 * 1024 * 1024) == 0) { // Every 64MB
@@ -282,7 +313,8 @@ int add_entropy_chacha20(const char* pad_chksum, const unsigned char* entropy_da
 
     if (display_progress) {
         show_progress(pad_size, pad_size, start_time);
-        printf("\n✓ Entropy successfully added to pad using Chacha20\n");
+        printf("\n✓ Entropy successfully added to pad using Chacha20%s\n",
+               use_extended ? " (extended counter)" : "");
         printf("✓ Pad integrity maintained\n");
         printf("✓ %zu bytes of entropy distributed across entire pad\n", entropy_size);
         printf("✓ Pad restored to read-only mode\n");

src/main.h

@@ -23,7 +23,7 @@
 #include <ctype.h>
 
 // Version - Updated automatically by build.sh
-#define OTP_VERSION "v0.3.34"
+#define OTP_VERSION "v0.3.49"
 
 // Constants
 #define MAX_INPUT_SIZE 4096
@@ -130,6 +130,7 @@ char* get_preferred_editor(void);
 char* get_preferred_file_manager(void);
 int launch_text_editor(const char* initial_content, char* result_buffer, size_t buffer_size);
 int launch_file_manager(const char* start_directory, char* selected_file, size_t buffer_size);
+int launch_directory_manager(const char* start_directory, char* selected_dir, size_t buffer_size);
 
 ////////////////////////////////////////////////////////////////////////////////
 //      CORE CRYPTOGRAPHIC OPERATIONS
@@ -238,6 +239,23 @@ int update_pad_checksum_after_entropy(const char* old_chksum, char* new_chksum);
 int rename_pad_files_safely(const char* old_chksum, const char* new_chksum);
 int is_pad_unused(const char* pad_chksum);
 
+////////////////////////////////////////////////////////////////////////////////
+//      DIRECTORY ARCHIVING AND COMPRESSION FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+// Directory encryption/decryption (TAR + GZIP + OTP)
+int encrypt_directory(const char* dir_path, const char* pad_identifier, const char* output_file);
+int decrypt_and_extract_directory(const char* encrypted_file, const char* output_dir);
+int is_compressed_tar_archive(const char* file_path);
+
+// TAR archive operations
+int create_tar_archive(const char* dir_path, const char* tar_output_path);
+int extract_tar_archive(const char* tar_path, const char* output_dir);
+
+// Compression operations
+int compress_file_gzip(const char* input_path, const char* output_path);
+int decompress_file_gzip(const char* input_path, const char* output_path);
+
 ////////////////////////////////////////////////////////////////////////////////
 //      DIRECTORY MANAGEMENT FUNCTIONS
 ////////////////////////////////////////////////////////////////////////////////
@@ -249,6 +267,16 @@ const char* get_files_directory(void);
 void get_default_file_path(const char* filename, char* result_path, size_t result_size);
 void get_directory_display(const char* file_path, char* result, size_t result_size);
 
+////////////////////////////////////////////////////////////////////////////////
+//      MESSAGE PADDING FUNCTIONS
+////////////////////////////////////////////////////////////////////////////////
+
+// Exponential bucketing and ISO/IEC 9797-1 Method 2 (Padmé) padding
+size_t calculate_chunk_size(size_t msg_len);
+int apply_padme_padding(unsigned char* buffer, size_t msg_len, size_t chunk_size);
+int remove_padme_padding(const unsigned char* buffer, size_t chunk_size, size_t* msg_len);
+void format_chunk_size(size_t chunk_size, char* buffer, size_t buffer_size);
+
 ////////////////////////////////////////////////////////////////////////////////
 //      UTILITY FUNCTIONS
 ////////////////////////////////////////////////////////////////////////////////
@@ -259,6 +287,7 @@ char* find_pad_by_prefix(const char* prefix);
 int show_pad_info(const char* chksum);
 void show_progress(uint64_t current, uint64_t total, time_t start_time);
 void format_time_remaining(double seconds, char* buffer, size_t buffer_size);
+int is_escape_input(const char* input);
 
 ////////////////////////////////////////////////////////////////////////////////
 //      FILE OPERATIONS
@@ -314,6 +343,7 @@ int handle_decrypt_menu(void);
 int handle_pads_menu(void);
 int handle_text_encrypt(void);
 int handle_file_encrypt(void);
+int handle_directory_encrypt(void);
 int handle_verify_pad(const char* pad_chksum);
 int handle_delete_pad(const char* pad_chksum);
 

src/nostr_chacha20.c

@@ -161,3 +161,45 @@ int chacha20_encrypt(const uint8_t key[32], uint32_t counter,
     
     return 0;
 }
+
+int chacha20_encrypt_extended(const uint8_t key[32], uint32_t counter_low,
+                               uint32_t counter_high, const uint8_t nonce[8],
+                               const uint8_t* input, uint8_t* output, size_t length) {
+    uint8_t keystream[CHACHA20_BLOCK_SIZE];
+    uint8_t extended_nonce[12];
+    size_t offset = 0;
+    
+    while (length > 0) {
+        /* Build extended 12-byte nonce: [counter_high (4 bytes)][nonce (8 bytes)] */
+        u32_to_bytes_le(counter_high, extended_nonce);
+        memcpy(extended_nonce + 4, nonce, 8);
+        
+        /* Generate keystream block using extended nonce */
+        int ret = chacha20_block(key, counter_low, extended_nonce, keystream);
+        if (ret != 0) {
+            return ret;
+        }
+        
+        /* XOR with input to produce output */
+        size_t block_len = (length < CHACHA20_BLOCK_SIZE) ? length : CHACHA20_BLOCK_SIZE;
+        for (size_t i = 0; i < block_len; i++) {
+            output[offset + i] = input[offset + i] ^ keystream[i];
+        }
+        
+        /* Move to next block */
+        offset += block_len;
+        length -= block_len;
+        counter_low++;
+        
+        /* Check for counter_low overflow and increment counter_high */
+        if (counter_low == 0) {
+            counter_high++;
+            /* Check for counter_high overflow (extremely unlikely - > 1 exabyte) */
+            if (counter_high == 0) {
+                return -1; /* Extended counter wrapped around */
+            }
+        }
+    }
+    
+    return 0;
+}

src/nostr_chacha20.h

@@ -79,6 +79,25 @@ int chacha20_encrypt(const uint8_t key[32], uint32_t counter,
                      const uint8_t nonce[12], const uint8_t* input,
                      uint8_t* output, size_t length);
 
+/**
+ * ChaCha20 encryption/decryption with extended counter (64-bit)
+ *
+ * Extended version that supports files larger than 256GB by using
+ * part of the nonce as a high-order counter extension.
+ *
+ * @param key[in]           32-byte key
+ * @param counter_low[in]   Initial 32-bit counter value (low bits)
+ * @param counter_high[in]  Initial 32-bit counter value (high bits)
+ * @param nonce[in]         8-byte reduced nonce (instead of 12)
+ * @param input[in]         Input data to encrypt/decrypt
+ * @param output[out]       Output buffer (can be same as input)
+ * @param length[in]        Length of input data in bytes
+ * @return                  0 on success, negative on error
+ */
+int chacha20_encrypt_extended(const uint8_t key[32], uint32_t counter_low,
+                               uint32_t counter_high, const uint8_t nonce[8],
+                               const uint8_t* input, uint8_t* output, size_t length);
+
 /*
  * ============================================================================
  * UTILITY FUNCTIONS

src/padding.c

@@ -0,0 +1,92 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include "main.h"
+
+////////////////////////////////////////////////////////////////////////////////
+//      MESSAGE PADDING IMPLEMENTATION
+//      ISO/IEC 9797-1 Method 2 (Padmé Padding)
+//      with Exponential Bucketing for Traffic Analysis Resistance
+////////////////////////////////////////////////////////////////////////////////
+
+// Calculate required chunk size using exponential bucketing
+// Starting at 256 bytes, doubling each time
+// Provides strong protection against length analysis attacks
+size_t calculate_chunk_size(size_t msg_len) {
+    size_t chunk = 256;  // Minimum chunk size: 256 bytes
+    
+    // Need space for message + 0x80 byte (minimum 1 byte padding)
+    while (chunk < msg_len + 1) {
+        chunk *= 2;
+    }
+    
+    return chunk;
+}
+
+// Apply ISO/IEC 9797-1 Method 2 (Padmé) padding
+// Appends 0x80 byte followed by 0x00 bytes to reach chunk boundary
+// Returns 0 on success, non-zero on error
+int apply_padme_padding(unsigned char* buffer, size_t msg_len, size_t chunk_size) {
+    if (!buffer) {
+        return 1; // Error: null pointer
+    }
+    
+    if (chunk_size < msg_len + 1) {
+        return 2; // Error: chunk size too small for message + padding
+    }
+    
+    // Apply padding: 0x80 followed by 0x00 bytes
+    buffer[msg_len] = 0x80;
+    
+    // Fill remaining bytes with 0x00
+    if (chunk_size > msg_len + 1) {
+        memset(buffer + msg_len + 1, 0x00, chunk_size - msg_len - 1);
+    }
+    
+    return 0; // Success
+}
+
+// Remove ISO/IEC 9797-1 Method 2 (Padmé) padding
+// Scans backwards for 0x80 marker, validates padding
+// Returns 0 on success, non-zero on error
+// Sets msg_len to the actual message length (excluding padding)
+int remove_padme_padding(const unsigned char* buffer, size_t chunk_size, size_t* msg_len) {
+    if (!buffer || !msg_len) {
+        return 1; // Error: null pointer
+    }
+    
+    if (chunk_size == 0) {
+        return 2; // Error: invalid chunk size
+    }
+    
+    // Scan backwards from end to find 0x80 marker
+    for (int i = chunk_size - 1; i >= 0; i--) {
+        if (buffer[i] == 0x80) {
+            // Found the padding marker
+            *msg_len = i;
+            return 0; // Success
+        } else if (buffer[i] != 0x00) {
+            // Found non-zero, non-0x80 byte - invalid padding
+            return 3; // Error: invalid padding (corrupted or tampered data)
+        }
+    }
+    
+    // No 0x80 marker found - invalid padding
+    return 4; // Error: no padding marker found
+}
+
+// Helper function to get human-readable chunk size
+// Useful for debugging and user feedback
+void format_chunk_size(size_t chunk_size, char* buffer, size_t buffer_size) {
+    if (!buffer || buffer_size == 0) return;
+    
+    if (chunk_size < 1024) {
+        snprintf(buffer, buffer_size, "%zu bytes", chunk_size);
+    } else if (chunk_size < 1024 * 1024) {
+        snprintf(buffer, buffer_size, "%.1f KB", chunk_size / 1024.0);
+    } else if (chunk_size < 1024 * 1024 * 1024) {
+        snprintf(buffer, buffer_size, "%.1f MB", chunk_size / (1024.0 * 1024.0));
+    } else {
+        snprintf(buffer, buffer_size, "%.1f GB", chunk_size / (1024.0 * 1024.0 * 1024.0));
+    }
+}

src/pads.c

@@ -253,10 +253,10 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
     }
 
     // Initialize state file with offset 32 (first 32 bytes reserved for checksum encryption)
-    FILE* state_file = fopen(state_path, "wb");
+    FILE* state_file = fopen(state_path, "w");
     if (state_file) {
         uint64_t reserved_bytes = 32;
-        fwrite(&reserved_bytes, sizeof(uint64_t), 1, state_file);
+        fprintf(state_file, "offset=%lu\n", reserved_bytes);
         fclose(state_file);
     } else {
         printf("Error: Failed to create state file\n");
@@ -292,7 +292,7 @@ int read_state_offset(const char* pad_chksum, uint64_t* offset) {
         return 0;
     }
 
-    // Try to read as text format first (new format)
+    // Read text format only (required format: "offset=<number>")
     char line[128];
     if (fgets(line, sizeof(line), state_file)) {
         // Check if it's text format (starts with "offset=")
@@ -302,21 +302,13 @@ int read_state_offset(const char* pad_chksum, uint64_t* offset) {
             return 0;
         }
         
-        // Not text format, try binary format (legacy)
+        // Not in proper text format - error
         fclose(state_file);
-        state_file = fopen(state_filename, "rb");
+        fprintf(stderr, "Error: State file '%s' is not in proper text format\n", state_filename);
-        if (!state_file) {
+        fprintf(stderr, "Expected format: offset=<number>\n");
+        fprintf(stderr, "Please convert old binary state files to text format\n");
         *offset = 0;
-            return 0;
+        return 1;
-        }
-        
-        if (fread(offset, sizeof(uint64_t), 1, state_file) != 1) {
-            fclose(state_file);
-            *offset = 0;
-            return 0;
-        }
-        fclose(state_file);
-        return 0;
     }
 
     fclose(state_file);
@@ -478,6 +470,13 @@ char* select_pad_interactive(const char* title, const char* prompt, pad_filter_t
         return NULL;
     }
 
+    // If only one pad available, auto-select it
+    if (pad_count == 1) {
+        printf("\n%s\n", title);
+        printf("Only one pad available - auto-selecting: %.16s...\n\n", pads[0].chksum);
+        return strdup(pads[0].chksum);
+    }
+
     // Calculate minimal unique prefixes for each pad
     char prefixes[100][65];
     int prefix_lengths[100];

src/state.c

@@ -1,10 +1,12 @@
 #include <string.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include "main.h"
 
 // Global state variables
-static char current_pads_dir[512] = DEFAULT_PADS_DIR;
+static char current_pads_dir[512] = "";
 static int is_interactive_mode = 0;
+static int pads_dir_initialized = 0;
 
 // Terminal dimensions (moved from ui.c to state.c for global access)
 static int terminal_width = 80;  // Default fallback width
@@ -13,6 +15,18 @@ static int terminal_height = 24; // Default fallback height
 // Getters and setters for global state
 
 const char* get_current_pads_dir(void) {
+    // Initialize pads directory on first access if not already set
+    if (!pads_dir_initialized && strlen(current_pads_dir) == 0) {
+        char* home_dir = getenv("HOME");
+        if (home_dir) {
+            snprintf(current_pads_dir, sizeof(current_pads_dir), "%s/.otp/pads", home_dir);
+        } else {
+            // Fallback to relative path if HOME is not set
+            strncpy(current_pads_dir, DEFAULT_PADS_DIR, sizeof(current_pads_dir) - 1);
+        }
+        current_pads_dir[sizeof(current_pads_dir) - 1] = '\0';
+        pads_dir_initialized = 1;
+    }
     return current_pads_dir;
 }
 
@@ -20,6 +34,7 @@ void set_current_pads_dir(const char* dir) {
     if (dir) {
         strncpy(current_pads_dir, dir, sizeof(current_pads_dir) - 1);
         current_pads_dir[sizeof(current_pads_dir) - 1] = '\0';
+        pads_dir_initialized = 1;
     }
 }
 

src/ui.c

@@ -99,6 +99,9 @@ int interactive_mode(void) {
             case 'F':
                 handle_file_encrypt();
                 break;
+            case 'R':
+                handle_directory_encrypt();
+                break;
             case 'D':
                 handle_decrypt_menu();
                 break;
@@ -127,6 +130,7 @@ void show_main_menu(void) {
 
     printf(" \033[4mT\033[0mext encrypt\n");       //TEXT ENCRYPT
     printf(" \033[4mF\033[0mile encrypt\n");       //FILE ENCRYPT
+    printf(" Di\033[4mr\033[0mectory encrypt\n");  //DIRECTORY ENCRYPT
     printf(" \033[4mD\033[0mecrypt\n");            //DECRYPT
     printf(" \033[4mP\033[0mads\n");               //PADS
     printf(" E\033[4mx\033[0mit\n");               //EXIT
@@ -180,7 +184,7 @@ int handle_encrypt_menu(void) {
     printf("\nSelect encryption type:\n");
     printf(" 1. Text message\n");
     printf(" 2. File\n");
-    printf("Enter choice (1-2): ");
+    printf("Enter choice (1-2) or 'esc' to cancel: ");
 
     char choice_input[10];
     if (!fgets(choice_input, sizeof(choice_input), stdin)) {
@@ -188,6 +192,14 @@ int handle_encrypt_menu(void) {
         return 1;
     }
 
+    choice_input[strcspn(choice_input, "\n")] = 0;
+    
+    // Check for ESC/cancel
+    if (is_escape_input(choice_input)) {
+        printf("Returning to main menu...\n");
+        return 0;
+    }
+
     int choice = atoi(choice_input);
 
     if (choice == 1) {
@@ -209,7 +221,7 @@ int handle_encrypt_menu(void) {
         printf("\nFile selection options:\n");
         printf(" 1. Type file path directly\n");
         printf(" 2. Use file manager\n");
-        printf("Enter choice (1-2): ");
+        printf("Enter choice (1-2) or 'esc' to cancel: ");
 
         char file_choice[10];
         char input_file[512];
@@ -219,25 +231,45 @@ int handle_encrypt_menu(void) {
             return 1;
         }
 
+        file_choice[strcspn(file_choice, "\n")] = 0;
+        
+        // Check for ESC/cancel
+        if (is_escape_input(file_choice)) {
+            printf("Returning to main menu...\n");
+            return 0;
+        }
+
         if (atoi(file_choice) == 2) {
             // Use file manager
             if (launch_file_manager(".", input_file, sizeof(input_file)) != 0) {
                 printf("Falling back to manual file path entry.\n");
-                printf("Enter input file path: ");
+                printf("Enter input file path (or 'esc' to cancel): ");
                 if (!fgets(input_file, sizeof(input_file), stdin)) {
                     printf("Error: Failed to read input\n");
                     return 1;
                 }
                 input_file[strcspn(input_file, "\n")] = 0;
+                
+                // Check for ESC/cancel
+                if (is_escape_input(input_file)) {
+                    printf("Returning to main menu...\n");
+                    return 0;
+                }
             }
         } else {
             // Direct file path input
-            printf("Enter input file path: ");
+            printf("Enter input file path (or 'esc' to cancel): ");
             if (!fgets(input_file, sizeof(input_file), stdin)) {
                 printf("Error: Failed to read input\n");
                 return 1;
             }
             input_file[strcspn(input_file, "\n")] = 0;
+            
+            // Check for ESC/cancel
+            if (is_escape_input(input_file)) {
+                printf("Returning to main menu...\n");
+                return 0;
+            }
         }
 
         // Check if file exists
@@ -259,14 +291,24 @@ int handle_encrypt_menu(void) {
         printf("\nSelect output format:\n");
         printf(" 1. Binary (.otp) - preserves file permissions\n");
         printf(" 2. ASCII (.otp.asc) - text-safe format\n");
-        printf("Enter choice (1-2): ");
+        printf("Enter choice (1-2) or 'esc' to cancel: ");
 
         char format_input[10];
         if (!fgets(format_input, sizeof(format_input), stdin)) {
             printf("Error: Failed to read input\n");
+            free(selected_pad);
             return 1;
         }
 
+        format_input[strcspn(format_input, "\n")] = 0;
+        
+        // Check for ESC/cancel
+        if (is_escape_input(format_input)) {
+            printf("Returning to main menu...\n");
+            free(selected_pad);
+            return 0;
+        }
+
         int ascii_armor = (atoi(format_input) == 2) ? 1 : 0;
 
         // Generate default output filename with files directory and use enhanced input function
@@ -305,6 +347,7 @@ int handle_decrypt_menu(void) {
     printf("\n");
     print_centered_header("Smart Decrypt", 0);
     printf("Enter encrypted data (paste ASCII armor), file path, or press Enter to browse files:\n");
+    printf("(Type 'esc' or 'q' to return to main menu)\n");
 
     char input_line[MAX_LINE_LENGTH];
     if (!fgets(input_line, sizeof(input_line), stdin)) {
@@ -315,46 +358,21 @@ int handle_decrypt_menu(void) {
     // Remove newline
     input_line[strcspn(input_line, "\n")] = 0;
 
-    if (strlen(input_line) == 0) {
+    // Check for ESC/cancel
-        // Empty input - launch file manager to browse for files
+    if (is_escape_input(input_line)) {
-        char selected_file[512];
+        printf("Returning to main menu...\n");
-        if (launch_file_manager(get_files_directory(), selected_file, sizeof(selected_file)) != 0) {
+        return 0;
-            printf("Error: Could not launch file manager\n");
-            return 1;
     }
 
-        // Generate smart default output filename with files directory and use enhanced input function
+    // Trim leading whitespace to handle pasted content better
-        char temp_default[512];
+    char* trimmed_input = input_line;
-        char default_output[512];
+    while (*trimmed_input == ' ' || *trimmed_input == '\t') {
-        strncpy(temp_default, selected_file, sizeof(temp_default) - 1);
+        trimmed_input++;
-        temp_default[sizeof(temp_default) - 1] = '\0';
-
-        // Remove common encrypted extensions to get a better default
-        if (strstr(temp_default, ".otp.asc")) {
-            // Replace .otp.asc with original extension or no extension
-            char* ext_pos = strstr(temp_default, ".otp.asc");
-            *ext_pos = '\0';
-        } else if (strstr(temp_default, ".otp")) {
-            // Replace .otp with original extension or no extension
-            char* ext_pos = strstr(temp_default, ".otp");
-            *ext_pos = '\0';
-        } else {
-            // No recognized encrypted extension, add .decrypted suffix
-            strncat(temp_default, ".decrypted", sizeof(temp_default) - strlen(temp_default) - 1);
     }
 
-        // Apply files directory default path
+    // Check for ASCII armor FIRST, before checking for empty input
-        get_default_file_path(temp_default, default_output, sizeof(default_output));
+    // This handles cases where pasted text starts with the header
-
+    if (strncmp(trimmed_input, "-----BEGIN OTP MESSAGE-----", 27) == 0) {
-        char output_file[512];
-        if (get_filename_with_default("Output filename:", default_output, output_file, sizeof(output_file)) != 0) {
-            printf("Error: Failed to read input\n");
-            return 1;
-        }
-
-        return decrypt_file(selected_file, output_file);
-    }
-    else if (strncmp(input_line, "-----BEGIN OTP MESSAGE-----", 27) == 0) {
         // Looks like ASCII armor - collect the full message
         char full_message[MAX_INPUT_SIZE * 4] = {0};
         strcat(full_message, input_line);
@@ -372,17 +390,31 @@ int handle_decrypt_menu(void) {
 
         return decrypt_text(NULL, full_message);
     }
-    else {
+    else if (strlen(trimmed_input) == 0) {
-        // Check if it looks like a file path
+        // Empty input - launch file manager to browse for files
-        if (access(input_line, R_OK) == 0) {
+        char selected_file[512];
-            // It's a valid file - decrypt it with enhanced input for output filename
+        if (launch_file_manager(get_files_directory(), selected_file, sizeof(selected_file)) != 0) {
+            printf("File browsing cancelled or failed.\n");
+            printf("Returning to main menu...\n");
+            return 0;
+        }
+
+        // Generate smart default output filename with files directory and use enhanced input function
         char temp_default[512];
         char default_output[512];
-            strncpy(temp_default, input_line, sizeof(temp_default) - 1);
+        strncpy(temp_default, selected_file, sizeof(temp_default) - 1);
         temp_default[sizeof(temp_default) - 1] = '\0';
 
         // Remove common encrypted extensions to get a better default
-            if (strstr(temp_default, ".otp.asc")) {
+        if (strstr(temp_default, ".tar.gz.otp")) {
+            // Directory archive - remove .tar.gz.otp to get original directory name
+            char* ext_pos = strstr(temp_default, ".tar.gz.otp");
+            *ext_pos = '\0';
+        } else if (strstr(temp_default, ".tar.otp")) {
+            // Directory archive without compression - remove .tar.otp
+            char* ext_pos = strstr(temp_default, ".tar.otp");
+            *ext_pos = '\0';
+        } else if (strstr(temp_default, ".otp.asc")) {
             // Replace .otp.asc with original extension or no extension
             char* ext_pos = strstr(temp_default, ".otp.asc");
             *ext_pos = '\0';
@@ -404,7 +436,81 @@ int handle_decrypt_menu(void) {
             return 1;
         }
 
-            return decrypt_file(input_line, output_file);
+        // Check if it's a directory archive
+        if (strstr(selected_file, ".tar.gz.otp") || strstr(selected_file, ".tar.otp")) {
+            // It's a directory archive - extract to directory
+            char extract_dir[512];
+            strncpy(extract_dir, output_file, sizeof(extract_dir) - 1);
+            extract_dir[sizeof(extract_dir) - 1] = '\0';
+            
+            // Remove .tar.gz.otp or .tar.otp extension to get directory name
+            char* ext = strstr(extract_dir, ".tar.gz.otp");
+            if (!ext) ext = strstr(extract_dir, ".tar.otp");
+            if (ext) *ext = '\0';
+            
+            printf("Extracting directory archive to: %s/\n", extract_dir);
+            return decrypt_and_extract_directory(selected_file, extract_dir);
+        } else {
+            return decrypt_file(selected_file, output_file);
+        }
+    }
+    else {
+        // Check if it looks like a file path
+        if (access(trimmed_input, R_OK) == 0) {
+            // It's a valid file - decrypt it with enhanced input for output filename
+            char temp_default[512];
+            char default_output[512];
+            strncpy(temp_default, trimmed_input, sizeof(temp_default) - 1);
+            temp_default[sizeof(temp_default) - 1] = '\0';
+
+            // Remove common encrypted extensions to get a better default
+            if (strstr(temp_default, ".tar.gz.otp")) {
+                // Directory archive - remove .tar.gz.otp to get original directory name
+                char* ext_pos = strstr(temp_default, ".tar.gz.otp");
+                *ext_pos = '\0';
+            } else if (strstr(temp_default, ".tar.otp")) {
+                // Directory archive without compression - remove .tar.otp
+                char* ext_pos = strstr(temp_default, ".tar.otp");
+                *ext_pos = '\0';
+            } else if (strstr(temp_default, ".otp.asc")) {
+                // Replace .otp.asc with original extension or no extension
+                char* ext_pos = strstr(temp_default, ".otp.asc");
+                *ext_pos = '\0';
+            } else if (strstr(temp_default, ".otp")) {
+                // Replace .otp with original extension or no extension
+                char* ext_pos = strstr(temp_default, ".otp");
+                *ext_pos = '\0';
+            } else {
+                // No recognized encrypted extension, add .decrypted suffix
+                strncat(temp_default, ".decrypted", sizeof(temp_default) - strlen(temp_default) - 1);
+            }
+
+            // Apply files directory default path
+            get_default_file_path(temp_default, default_output, sizeof(default_output));
+
+            char output_file[512];
+            if (get_filename_with_default("Output filename:", default_output, output_file, sizeof(output_file)) != 0) {
+                printf("Error: Failed to read input\n");
+                return 1;
+            }
+
+            // Check if it's a directory archive
+            if (strstr(trimmed_input, ".tar.gz.otp") || strstr(trimmed_input, ".tar.otp")) {
+                // It's a directory archive - extract to directory
+                char extract_dir[512];
+                strncpy(extract_dir, output_file, sizeof(extract_dir) - 1);
+                extract_dir[sizeof(extract_dir) - 1] = '\0';
+                
+                // Remove .tar.gz.otp or .tar.otp extension to get directory name
+                char* ext = strstr(extract_dir, ".tar.gz.otp");
+                if (!ext) ext = strstr(extract_dir, ".tar.otp");
+                if (ext) *ext = '\0';
+                
+                printf("Extracting directory archive to: %s/\n", extract_dir);
+                return decrypt_and_extract_directory(trimmed_input, extract_dir);
+            } else {
+                return decrypt_file(trimmed_input, output_file);
+            }
         } else {
             printf("Input not recognized as ASCII armor or valid file path.\n");
             return 1;
@@ -472,14 +578,24 @@ int handle_file_encrypt(void) {
     printf("\nSelect output format:\n");
     printf(" 1. Binary (.otp) - preserves file permissions\n");
     printf(" 2. ASCII (.otp.asc) - text-safe format\n");
-    printf("Enter choice (1-2): ");
+    printf("Enter choice (1-2) or 'esc' to cancel: ");
 
     char format_input[10];
     if (!fgets(format_input, sizeof(format_input), stdin)) {
         printf("Error: Failed to read input\n");
+        free(selected_pad);
         return 1;
     }
 
+    format_input[strcspn(format_input, "\n")] = 0;
+    
+    // Check for ESC/cancel
+    if (is_escape_input(format_input)) {
+        printf("Returning to main menu...\n");
+        free(selected_pad);
+        return 0;
+    }
+
     int ascii_armor = (atoi(format_input) == 2) ? 1 : 0;
 
     // Generate default output filename
@@ -503,3 +619,301 @@ int handle_file_encrypt(void) {
     free(selected_pad);
     return result;
 }
+
+// Comparison function for qsort (case-insensitive)
+static int compare_dir_strings(const void *a, const void *b) {
+    return strcasecmp(*(const char**)a, *(const char**)b);
+}
+
+// Function to get list of subdirectories
+static int get_subdirs(const char *path, char ***subdirs) {
+    DIR *dir = opendir(path);
+    if (!dir) return 0;
+    
+    int count = 0;
+    int capacity = 10;
+    *subdirs = malloc(capacity * sizeof(char*));
+    
+    struct dirent *entry;
+    while ((entry = readdir(dir)) != NULL) {
+        if (entry->d_type == DT_DIR) {
+            // Skip . and ..
+            if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
+                continue;
+            
+            if (count >= capacity) {
+                capacity *= 2;
+                *subdirs = realloc(*subdirs, capacity * sizeof(char*));
+            }
+            (*subdirs)[count++] = strdup(entry->d_name);
+        }
+    }
+    closedir(dir);
+    
+    // Sort alphabetically
+    if (count > 0) {
+        qsort(*subdirs, count, sizeof(char*), compare_dir_strings);
+    }
+    
+    return count;
+}
+
+// Function to get a single keypress without echo
+static int getch_nav(void) {
+    struct termios oldt, newt;
+    int ch;
+    tcgetattr(STDIN_FILENO, &oldt);
+    newt = oldt;
+    newt.c_lflag &= ~(ICANON | ECHO);
+    tcsetattr(STDIN_FILENO, TCSANOW, &newt);
+    ch = getchar();
+    tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
+    return ch;
+}
+
+// Navigate directories with arrow keys
+static char* navigate_directory_interactive(void) {
+    char current_path[PATH_MAX];
+    char original_path[PATH_MAX];
+    getcwd(original_path, sizeof(original_path));
+    getcwd(current_path, sizeof(current_path));
+    
+    char **subdirs = NULL;
+    int subdir_count = 0;
+    int current_index = 0;
+    
+    printf("\nNavigate with arrow keys (UP/DOWN: cycle, RIGHT: enter, LEFT: back, ENTER: select, Q: cancel)\n");
+    printf("\033[?25l"); // Hide cursor
+    
+    while (1) {
+        // Clear line and show current path
+        printf("\r\033[K%s", current_path);
+        
+        // If we have subdirectories and an index, show current selection
+        if (subdir_count > 0 && current_index < subdir_count) {
+            printf("/%s", subdirs[current_index]);
+        }
+        
+        fflush(stdout);
+        
+        int ch = getch_nav();
+        
+        // Handle arrow keys (they come as escape sequences)
+        if (ch == 27) { // ESC sequence
+            getch_nav(); // Skip '['
+            ch = getch_nav();
+            
+            if (ch == 'A') { // UP arrow
+                // Load subdirs if not loaded
+                if (subdirs == NULL) {
+                    subdir_count = get_subdirs(current_path, &subdirs);
+                    current_index = 0;
+                } else if (subdir_count > 0) {
+                    current_index = (current_index - 1 + subdir_count) % subdir_count;
+                }
+            }
+            else if (ch == 'B') { // DOWN arrow
+                // Load subdirs if not loaded
+                if (subdirs == NULL) {
+                    subdir_count = get_subdirs(current_path, &subdirs);
+                    current_index = 0;
+                } else if (subdir_count > 0) {
+                    current_index = (current_index + 1) % subdir_count;
+                }
+            }
+            else if (ch == 'C') { // RIGHT arrow - go deeper
+                if (subdir_count > 0 && current_index < subdir_count) {
+                    // Navigate into selected directory
+                    char new_path[PATH_MAX];
+                    snprintf(new_path, sizeof(new_path), "%s/%s", current_path, subdirs[current_index]);
+                    
+                    if (chdir(new_path) == 0) {
+                        getcwd(current_path, sizeof(current_path));
+                        
+                        // Free old subdirs
+                        for (int i = 0; i < subdir_count; i++) {
+                            free(subdirs[i]);
+                        }
+                        free(subdirs);
+                        subdirs = NULL;
+                        
+                        // Load subdirs of new directory and show first one
+                        subdir_count = get_subdirs(current_path, &subdirs);
+                        current_index = 0;
+                    }
+                }
+            }
+            else if (ch == 'D') { // LEFT arrow - go up
+                if (chdir("..") == 0) {
+                    getcwd(current_path, sizeof(current_path));
+                    
+                    // Free old subdirs
+                    for (int i = 0; i < subdir_count; i++) {
+                        free(subdirs[i]);
+                    }
+                    free(subdirs);
+                    subdirs = NULL;
+                    subdir_count = 0;
+                    current_index = 0;
+                }
+            }
+        }
+        else if (ch == '\n' || ch == '\r') { // ENTER - confirm selection
+            // If a subdirectory is displayed, navigate into it first
+            if (subdir_count > 0 && current_index < subdir_count) {
+                char new_path[PATH_MAX];
+                snprintf(new_path, sizeof(new_path), "%s/%s", current_path, subdirs[current_index]);
+                
+                if (chdir(new_path) == 0) {
+                    getcwd(current_path, sizeof(current_path));
+                }
+            }
+            break;
+        }
+        else if (ch == 'q' || ch == 'Q') { // Q to quit
+            printf("\033[?25h\n"); // Show cursor
+            // Restore original directory
+            chdir(original_path);
+            // Clean up
+            for (int i = 0; i < subdir_count; i++) {
+                free(subdirs[i]);
+            }
+            free(subdirs);
+            return NULL;
+        }
+    }
+    
+    printf("\033[?25h\n"); // Show cursor
+    
+    // Clean up
+    for (int i = 0; i < subdir_count; i++) {
+        free(subdirs[i]);
+    }
+    free(subdirs);
+    
+    // Restore original directory before returning
+    char* result = strdup(current_path);
+    chdir(original_path);
+    
+    return result;
+}
+
+int handle_directory_encrypt(void) {
+    printf("\n");
+    print_centered_header("Directory Encrypt", 0);
+
+    // Directory selection options
+    printf("\nDirectory selection options:\n");
+    printf(" 1. Type directory path directly\n");
+    printf(" 2. Navigate with arrow keys\n");
+    printf(" 3. Use file manager (navigate to directory)\n");
+    printf("Enter choice (1-3) or 'esc' to cancel: ");
+
+    char choice_input[10];
+    char dir_path[512];
+
+    if (!fgets(choice_input, sizeof(choice_input), stdin)) {
+        printf("Error: Failed to read input\n");
+        return 1;
+    }
+
+    choice_input[strcspn(choice_input, "\n")] = 0;
+    
+    // Check for ESC/cancel
+    if (is_escape_input(choice_input)) {
+        printf("Returning to main menu...\n");
+        return 0;
+    }
+
+    int choice = atoi(choice_input);
+    
+    if (choice == 2) {
+        // Use arrow key navigation
+        char* selected = navigate_directory_interactive();
+        if (!selected) {
+            printf("Directory selection cancelled.\n");
+            return 0;
+        }
+        strncpy(dir_path, selected, sizeof(dir_path) - 1);
+        dir_path[sizeof(dir_path) - 1] = '\0';
+        free(selected);
+        printf("Selected: %s\n", dir_path);
+    }
+    else if (choice == 3) {
+        // Use directory manager
+        if (launch_directory_manager(".", dir_path, sizeof(dir_path)) != 0) {
+            printf("Falling back to manual directory path entry.\n");
+            printf("Enter directory path to encrypt (or 'esc' to cancel): ");
+            if (!fgets(dir_path, sizeof(dir_path), stdin)) {
+                printf("Error: Failed to read input\n");
+                return 1;
+            }
+            dir_path[strcspn(dir_path, "\n")] = 0;
+            
+            // Check for ESC/cancel
+            if (is_escape_input(dir_path)) {
+                printf("Returning to main menu...\n");
+                return 0;
+            }
+        }
+    } else {
+        // Direct directory path input
+        printf("Enter directory path to encrypt (or 'esc' to cancel): ");
+        if (!fgets(dir_path, sizeof(dir_path), stdin)) {
+            printf("Error: Failed to read input\n");
+            return 1;
+        }
+        dir_path[strcspn(dir_path, "\n")] = 0;
+        
+        // Check for ESC/cancel
+        if (is_escape_input(dir_path)) {
+            printf("Returning to main menu...\n");
+            return 0;
+        }
+    }
+
+    // Check if directory exists
+    struct stat st;
+    if (stat(dir_path, &st) != 0 || !S_ISDIR(st.st_mode)) {
+        printf("Error: '%s' is not a valid directory\n", dir_path);
+        return 1;
+    }
+
+    // Select pad
+    char* selected_pad = select_pad_interactive("Select Pad for Directory Encryption",
+                                              "Select pad (by prefix)",
+                                              PAD_FILTER_ALL, 1);
+    if (!selected_pad) {
+        printf("Directory encryption cancelled.\n");
+        return 1;
+    }
+
+    // Generate default output filename - append .tar.gz.otp to the directory path
+    char default_output[1024];
+    
+    // Remove trailing slash if present
+    char clean_path[512];
+    strncpy(clean_path, dir_path, sizeof(clean_path) - 1);
+    clean_path[sizeof(clean_path) - 1] = '\0';
+    
+    size_t path_len = strlen(clean_path);
+    if (path_len > 0 && clean_path[path_len - 1] == '/') {
+        clean_path[path_len - 1] = '\0';
+    }
+    
+    snprintf(default_output, sizeof(default_output), "%s.tar.gz.otp", clean_path);
+
+    // Get output filename
+    char output_file[512];
+    if (get_filename_with_default("Output filename:", default_output, output_file, sizeof(output_file)) != 0) {
+        printf("Error: Failed to read input\n");
+        free(selected_pad);
+        return 1;
+    }
+
+    // Encrypt directory
+    int result = encrypt_directory(dir_path, selected_pad, output_file);
+    free(selected_pad);
+    
+    return result;
+}

src/util.c

@@ -19,6 +19,7 @@
 
 // Global variables for preferences
 static char default_pad_path[1024] = "";
+static char pads_directory[1024] = "";
 
 void show_progress(uint64_t current, uint64_t total, time_t start_time) {
     time_t now = time(NULL);
@@ -161,7 +162,8 @@ int launch_text_editor(const char* initial_content, char* result_buffer, size_t
 
 char* get_preferred_file_manager(void) {
     // Try file managers in order of preference
-    const char* file_managers[] = {"ranger", "fzf", "nnn", "lf", NULL};
+    // fzf is first because it's more intuitive with fuzzy search
+    const char* file_managers[] = {"fzf", "ranger", "nnn", "lf", NULL};
 
     for (int i = 0; file_managers[i] != NULL; i++) {
         char command[512];
@@ -177,7 +179,8 @@ char* get_preferred_file_manager(void) {
 int launch_file_manager(const char* start_directory, char* selected_file, size_t buffer_size) {
     char* fm = get_preferred_file_manager();
     if (!fm) {
-        printf("No file manager found. Please install ranger, fzf, nnn, or lf.\n");
+        printf("No file manager found. Please install fzf, ranger, nnn, or lf.\n");
+        printf("Recommended: sudo apt install fzf\n");
         printf("Falling back to manual file path entry.\n");
         return 1; // Fall back to manual entry
     }
@@ -190,6 +193,13 @@ int launch_file_manager(const char* start_directory, char* selected_file, size_t
 
     printf("Opening %s for file selection...\n", fm);
     
+    // Show helpful instructions based on file manager
+    if (strcmp(fm, "fzf") == 0) {
+        printf("Instructions: Type to search, use arrow keys, press Enter to select\n");
+    } else if (strcmp(fm, "ranger") == 0) {
+        printf("Instructions: Arrow keys or j/k to navigate, Enter or l to select, q to quit\n");
+    }
+
     if (strcmp(fm, "ranger") == 0) {
         snprintf(command, sizeof(command), "cd '%s' && ranger --choosefile=%s",
                 start_directory ? start_directory : ".", temp_filename);
@@ -240,6 +250,103 @@ int launch_file_manager(const char* start_directory, char* selected_file, size_t
     return 1; // Fall back to manual entry
 }
 
+int launch_directory_manager(const char* start_directory, char* selected_dir, size_t buffer_size) {
+    char* fm = get_preferred_file_manager();
+    if (!fm) {
+        printf("No file manager found. Please install fzf, ranger, nnn, or lf.\n");
+        printf("Recommended: sudo apt install fzf\n");
+        printf("Falling back to manual directory path entry.\n");
+        return 1; // Fall back to manual entry
+    }
+
+    char temp_filename[64];
+    snprintf(temp_filename, sizeof(temp_filename), "/tmp/otp_dir_%ld.tmp", time(NULL));
+
+    char command[512];
+    int result = 1;
+
+    printf("Opening %s for directory selection...\n", fm);
+    
+    // Show helpful instructions based on file manager
+    if (strcmp(fm, "fzf") == 0) {
+        printf("Instructions: Type to search, use arrow keys, press Enter to select directory\n");
+    } else if (strcmp(fm, "ranger") == 0) {
+        printf("Instructions: Navigate INTO the directory, then press 'q' to quit and select it\n");
+    }
+
+    if (strcmp(fm, "ranger") == 0) {
+        snprintf(command, sizeof(command), "cd '%s' && ranger --choosedir=%s",
+                start_directory ? start_directory : ".", temp_filename);
+    } else if (strcmp(fm, "fzf") == 0) {
+        // fzf doesn't have directory-only mode easily, use find
+        snprintf(command, sizeof(command), "cd '%s' && find . -type d | fzf > %s",
+                start_directory ? start_directory : ".", temp_filename);
+    } else if (strcmp(fm, "nnn") == 0) {
+        snprintf(command, sizeof(command), "cd '%s' && nnn -p %s",
+                start_directory ? start_directory : ".", temp_filename);
+    } else if (strcmp(fm, "lf") == 0) {
+        snprintf(command, sizeof(command), "cd '%s' && lf -selection-path=%s",
+                start_directory ? start_directory : ".", temp_filename);
+    }
+
+    result = system(command);
+
+    if (result == 0 || result == 256) { // Some file managers return 256 on success
+        // Read selected directory from temp file
+        FILE* temp_file = fopen(temp_filename, "r");
+        if (temp_file) {
+            if (fgets(selected_dir, buffer_size, temp_file)) {
+                // Remove trailing newline
+                selected_dir[strcspn(selected_dir, "\n\r")] = 0;
+
+                // For relative paths, make absolute if needed
+                if (selected_dir[0] == '.' && selected_dir[1] == '/') {
+                    char current_dir[512];
+                    if (getcwd(current_dir, sizeof(current_dir))) {
+                        char abs_path[1024];
+                        snprintf(abs_path, sizeof(abs_path), "%s/%s", current_dir, selected_dir + 2);
+                        strncpy(selected_dir, abs_path, buffer_size - 1);
+                        selected_dir[buffer_size - 1] = '\0';
+                    }
+                } else if (selected_dir[0] != '/') {
+                    // Relative path without ./
+                    char current_dir[512];
+                    if (getcwd(current_dir, sizeof(current_dir))) {
+                        char abs_path[1024];
+                        snprintf(abs_path, sizeof(abs_path), "%s/%s", current_dir, selected_dir);
+                        strncpy(selected_dir, abs_path, buffer_size - 1);
+                        selected_dir[buffer_size - 1] = '\0';
+                    }
+                }
+
+                fclose(temp_file);
+                unlink(temp_filename);
+                free(fm);
+                return 0; // Success
+            }
+            fclose(temp_file);
+        }
+    }
+
+    // Clean up and indicate failure
+    unlink(temp_filename);
+    free(fm);
+    return 1; // Fall back to manual entry
+}
+
+// Helper function to check if input contains ESC key
+int is_escape_input(const char* input) {
+    // Check for ESC character (ASCII 27) or empty input after ESC
+    if (input && (input[0] == 27 || (input[0] == '\0' && strlen(input) == 0))) {
+        return 1;
+    }
+    // Also check for literal "esc" or "ESC" typed
+    if (input && (strcasecmp(input, "esc") == 0 || strcasecmp(input, "q") == 0)) {
+        return 1;
+    }
+    return 0;
+}
+
 // Stdin detection functions implementation
 int has_stdin_data(void) {
     // Check if stdin is a pipe/redirect (not a terminal)
@@ -429,6 +536,11 @@ int load_preferences(void) {
             if (strcmp(key, "default_pad") == 0) {
                 strncpy(default_pad_path, value, sizeof(default_pad_path) - 1);
                 default_pad_path[sizeof(default_pad_path) - 1] = '\0';
+            } else if (strcmp(key, "pads_directory") == 0) {
+                strncpy(pads_directory, value, sizeof(pads_directory) - 1);
+                pads_directory[sizeof(pads_directory) - 1] = '\0';
+                // Apply the pads directory from config
+                set_current_pads_dir(pads_directory);
             }
         }
     }
@@ -1032,6 +1144,12 @@ int save_preferences(void) {
     fprintf(file, "# OTP Preferences File\n");
     fprintf(file, "# This file is automatically generated and updated by the OTP program\n\n");
 
+    // Save pads directory
+    const char* current_pads = get_current_pads_dir();
+    if (current_pads && strlen(current_pads) > 0) {
+        fprintf(file, "pads_directory=%s\n", current_pads);
+    }
+
     if (strlen(default_pad_path) > 0) {
         fprintf(file, "default_pad=%s\n", default_pad_path);
     }

tests/test_chacha20_extended.c

@@ -0,0 +1,263 @@
+/*
+ * test_chacha20_extended.c - Test ChaCha20 extended counter implementation
+ * 
+ * This test verifies that the extended counter properly handles:
+ * 1. Counter overflow at 2^32 blocks (256GB boundary)
+ * 2. Correct keystream generation across the overflow boundary
+ * 3. No duplicate keystream blocks
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include "../src/nostr_chacha20.h"
+
+#define TEST_BLOCK_SIZE 64
+#define BLOCKS_NEAR_OVERFLOW 10  // Test blocks around overflow point
+
+// Test helper: Compare two blocks for equality
+int blocks_equal(const uint8_t* block1, const uint8_t* block2, size_t len) {
+    return memcmp(block1, block2, len) == 0;
+}
+
+// Test 1: Verify extended counter handles overflow correctly
+int test_counter_overflow() {
+    printf("Test 1: Counter overflow handling\n");
+    printf("  Testing counter transition from 0xFFFFFFFF to 0x00000000...\n");
+    
+    uint8_t key[32];
+    uint8_t nonce[8];
+    uint8_t input[TEST_BLOCK_SIZE];
+    uint8_t output1[TEST_BLOCK_SIZE];
+    uint8_t output2[TEST_BLOCK_SIZE];
+    uint8_t output3[TEST_BLOCK_SIZE];
+    
+    // Initialize test data
+    memset(key, 0xAA, 32);
+    memset(nonce, 0xBB, 8);
+    memset(input, 0, TEST_BLOCK_SIZE);
+    
+    // Test at counter_low = 0xFFFFFFFE, counter_high = 0
+    uint32_t counter_low = 0xFFFFFFFE;
+    uint32_t counter_high = 0;
+    
+    printf("  Block at counter_low=0xFFFFFFFE, counter_high=0...\n");
+    if (chacha20_encrypt_extended(key, counter_low, counter_high, nonce, 
+                                   input, output1, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Error at counter_low=0xFFFFFFFE\n");
+        return 1;
+    }
+    
+    // Test at counter_low = 0xFFFFFFFF, counter_high = 0
+    counter_low = 0xFFFFFFFF;
+    printf("  Block at counter_low=0xFFFFFFFF, counter_high=0...\n");
+    if (chacha20_encrypt_extended(key, counter_low, counter_high, nonce, 
+                                   input, output2, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Error at counter_low=0xFFFFFFFF\n");
+        return 1;
+    }
+    
+    // Test at counter_low = 0x00000000, counter_high = 1 (after overflow)
+    counter_low = 0x00000000;
+    counter_high = 1;
+    printf("  Block at counter_low=0x00000000, counter_high=1...\n");
+    if (chacha20_encrypt_extended(key, counter_low, counter_high, nonce, 
+                                   input, output3, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Error at counter_low=0x00000000, counter_high=1\n");
+        return 1;
+    }
+    
+    // Verify all three blocks are different (no keystream reuse)
+    if (blocks_equal(output1, output2, TEST_BLOCK_SIZE)) {
+        printf("  ❌ FAILED: Blocks at 0xFFFFFFFE and 0xFFFFFFFF are identical!\n");
+        return 1;
+    }
+    
+    if (blocks_equal(output2, output3, TEST_BLOCK_SIZE)) {
+        printf("  ❌ FAILED: Blocks at 0xFFFFFFFF,0 and 0x00000000,1 are identical!\n");
+        return 1;
+    }
+    
+    if (blocks_equal(output1, output3, TEST_BLOCK_SIZE)) {
+        printf("  ❌ FAILED: Blocks at 0xFFFFFFFE,0 and 0x00000000,1 are identical!\n");
+        return 1;
+    }
+    
+    printf("  ✓ All blocks are unique across overflow boundary\n");
+    printf("  ✓ PASSED\n\n");
+    return 0;
+}
+
+// Test 2: Simulate processing data that crosses 256GB boundary
+int test_large_file_simulation() {
+    printf("Test 2: Large file simulation (256GB+ boundary)\n");
+    printf("  Simulating processing across 256GB boundary...\n");
+    
+    uint8_t key[32];
+    uint8_t nonce[8];
+    uint8_t input[1024];
+    uint8_t output[1024];
+    
+    // Initialize test data
+    memset(key, 0x55, 32);
+    memset(nonce, 0x77, 8);
+    for (int i = 0; i < 1024; i++) {
+        input[i] = i & 0xFF;
+    }
+    
+    // Simulate being at 256GB - 512 bytes (just before overflow)
+    // 256GB = 2^32 blocks * 64 bytes = 274,877,906,944 bytes
+    // Block number at 256GB - 512 bytes = 2^32 - 8 blocks
+    uint32_t counter_low = 0xFFFFFFF8;  // 2^32 - 8
+    uint32_t counter_high = 0;
+    
+    printf("  Processing 1KB starting at block 0xFFFFFFF8 (256GB - 512 bytes)...\n");
+    
+    // This should cross the overflow boundary
+    int result = chacha20_encrypt_extended(key, counter_low, counter_high, nonce, 
+                                           input, output, 1024);
+    
+    if (result != 0) {
+        printf("  ❌ FAILED: Error processing data across 256GB boundary\n");
+        return 1;
+    }
+    
+    printf("  ✓ Successfully processed data across 256GB boundary\n");
+    printf("  ✓ PASSED\n\n");
+    return 0;
+}
+
+// Test 3: Verify extended vs standard ChaCha20 compatibility
+int test_compatibility() {
+    printf("Test 3: Compatibility with standard ChaCha20\n");
+    printf("  Verifying extended mode matches standard mode when counter_high=0...\n");
+    
+    uint8_t key[32];
+    uint8_t nonce_standard[12];
+    uint8_t nonce_reduced[8];
+    uint8_t input[TEST_BLOCK_SIZE];
+    uint8_t output_standard[TEST_BLOCK_SIZE];
+    uint8_t output_extended[TEST_BLOCK_SIZE];
+    
+    // Initialize test data
+    memset(key, 0x33, 32);
+    memset(nonce_standard, 0x44, 12);
+    memcpy(nonce_reduced, nonce_standard + 4, 8);  // Extract last 8 bytes
+    memset(input, 0, TEST_BLOCK_SIZE);
+    
+    uint32_t counter = 42;
+    
+    // Standard ChaCha20
+    if (chacha20_encrypt(key, counter, nonce_standard, input, 
+                        output_standard, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Standard ChaCha20 error\n");
+        return 1;
+    }
+    
+    // Extended ChaCha20 with counter_high=0 and matching nonce
+    // The extended version builds nonce as [counter_high][nonce_reduced]
+    // So we need to ensure the first 4 bytes of nonce_standard are 0
+    uint8_t nonce_standard_zero[12] = {0};
+    memcpy(nonce_standard_zero + 4, nonce_reduced, 8);
+    
+    if (chacha20_encrypt(key, counter, nonce_standard_zero, input, 
+                        output_standard, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Standard ChaCha20 error\n");
+        return 1;
+    }
+    
+    if (chacha20_encrypt_extended(key, counter, 0, nonce_reduced, input, 
+                                  output_extended, TEST_BLOCK_SIZE) != 0) {
+        printf("  ❌ FAILED: Extended ChaCha20 error\n");
+        return 1;
+    }
+    
+    // Compare outputs
+    if (!blocks_equal(output_standard, output_extended, TEST_BLOCK_SIZE)) {
+        printf("  ❌ FAILED: Extended mode output differs from standard mode\n");
+        printf("  First 16 bytes of standard: ");
+        for (int i = 0; i < 16; i++) printf("%02x ", output_standard[i]);
+        printf("\n  First 16 bytes of extended: ");
+        for (int i = 0; i < 16; i++) printf("%02x ", output_extended[i]);
+        printf("\n");
+        return 1;
+    }
+    
+    printf("  ✓ Extended mode matches standard mode when counter_high=0\n");
+    printf("  ✓ PASSED\n\n");
+    return 0;
+}
+
+// Test 4: Stress test - verify no errors at extreme counter values
+int test_extreme_values() {
+    printf("Test 4: Extreme counter values\n");
+    printf("  Testing at various extreme counter positions...\n");
+    
+    uint8_t key[32];
+    uint8_t nonce[8];
+    uint8_t input[TEST_BLOCK_SIZE];
+    uint8_t output[TEST_BLOCK_SIZE];
+    
+    memset(key, 0x99, 32);
+    memset(nonce, 0x66, 8);
+    memset(input, 0, TEST_BLOCK_SIZE);
+    
+    // Test various extreme positions
+    struct {
+        uint32_t counter_low;
+        uint32_t counter_high;
+        const char* description;
+    } test_cases[] = {
+        {0x00000000, 0, "Start of first 256GB segment"},
+        {0xFFFFFFFF, 0, "End of first 256GB segment"},
+        {0x00000000, 1, "Start of second 256GB segment"},
+        {0xFFFFFFFF, 1, "End of second 256GB segment"},
+        {0x00000000, 0xFFFF, "Start of segment 65535"},
+        {0xFFFFFFFF, 0xFFFF, "End of segment 65535"},
+    };
+    
+    for (size_t i = 0; i < sizeof(test_cases) / sizeof(test_cases[0]); i++) {
+        printf("  Testing: %s (0x%08X, 0x%08X)...\n", 
+               test_cases[i].description,
+               test_cases[i].counter_low,
+               test_cases[i].counter_high);
+        
+        if (chacha20_encrypt_extended(key, test_cases[i].counter_low, 
+                                      test_cases[i].counter_high, nonce,
+                                      input, output, TEST_BLOCK_SIZE) != 0) {
+            printf("  ❌ FAILED at %s\n", test_cases[i].description);
+            return 1;
+        }
+    }
+    
+    printf("  ✓ All extreme values handled correctly\n");
+    printf("  ✓ PASSED\n\n");
+    return 0;
+}
+
+int main() {
+    printf("=================================================================\n");
+    printf("ChaCha20 Extended Counter Test Suite\n");
+    printf("=================================================================\n\n");
+    
+    int failures = 0;
+    
+    failures += test_counter_overflow();
+    failures += test_large_file_simulation();
+    failures += test_compatibility();
+    failures += test_extreme_values();
+    
+    printf("=================================================================\n");
+    if (failures == 0) {
+        printf("✓ ALL TESTS PASSED\n");
+        printf("=================================================================\n");
+        printf("\nThe extended counter implementation is working correctly.\n");
+        printf("It can now handle pads larger than 256GB without overflow errors.\n");
+        return 0;
+    } else {
+        printf("❌ %d TEST(S) FAILED\n", failures);
+        printf("=================================================================\n");
+        return 1;
+    }
+}

tests/test_padding.sh

@@ -0,0 +1,129 @@
+#!/bin/bash
+# Test script for message padding implementation
+
+set -e
+
+echo "=== Testing Message Padding Implementation ==="
+echo ""
+
+# Colors
+GREEN='\033[0;32m'
+RED='\033[0;31m'
+NC='\033[0m' # No Color
+
+# Test counter
+TESTS_PASSED=0
+TESTS_FAILED=0
+
+# Function to run a test
+run_test() {
+    local test_name="$1"
+    local test_command="$2"
+    
+    echo -n "Testing: $test_name... "
+    if eval "$test_command" > /dev/null 2>&1; then
+        echo -e "${GREEN}PASS${NC}"
+        ((TESTS_PASSED++))
+        return 0
+    else
+        echo -e "${RED}FAIL${NC}"
+        ((TESTS_FAILED++))
+        return 1
+    fi
+}
+
+# Create a small test pad if it doesn't exist
+if [ ! -f "pads/"*.pad ]; then
+    echo "Creating test pad (1MB)..."
+    ./build/otp-x86_64 generate 1MB
+    echo ""
+fi
+
+# Get the first pad checksum
+PAD_CHKSUM=$(ls pads/*.pad | head -n 1 | xargs basename | sed 's/.pad$//')
+
+echo "Using pad: ${PAD_CHKSUM:0:16}..."
+echo ""
+
+# Test 1: Encrypt and decrypt a short message (should be padded to 256 bytes)
+echo "Test 1: Short message (10 bytes -> 256 bytes padded)"
+TEST_MSG="Hello Test"
+ENCRYPTED=$(echo "$TEST_MSG" | ./build/otp-x86_64 encrypt ${PAD_CHKSUM:0:8})
+DECRYPTED=$(echo "$ENCRYPTED" | ./build/otp-x86_64 decrypt)
+
+if [ "$DECRYPTED" = "$TEST_MSG" ]; then
+    echo -e "${GREEN}✓ Short message encryption/decryption successful${NC}"
+    ((TESTS_PASSED++))
+else
+    echo -e "${RED}✗ Short message failed${NC}"
+    echo "  Expected: $TEST_MSG"
+    echo "  Got: $DECRYPTED"
+    ((TESTS_FAILED++))
+fi
+echo ""
+
+# Test 2: Encrypt and decrypt a medium message (should be padded to 512 bytes)
+echo "Test 2: Medium message (~300 bytes -> 512 bytes padded)"
+TEST_MSG=$(printf 'A%.0s' {1..300})
+ENCRYPTED=$(echo "$TEST_MSG" | ./build/otp-x86_64 encrypt ${PAD_CHKSUM:0:8})
+DECRYPTED=$(echo "$ENCRYPTED" | ./build/otp-x86_64 decrypt)
+
+if [ "$DECRYPTED" = "$TEST_MSG" ]; then
+    echo -e "${GREEN}✓ Medium message encryption/decryption successful${NC}"
+    ((TESTS_PASSED++))
+else
+    echo -e "${RED}✗ Medium message failed${NC}"
+    ((TESTS_FAILED++))
+fi
+echo ""
+
+# Test 3: Encrypt and decrypt with special characters
+echo "Test 3: Special characters and unicode"
+TEST_MSG="Hello! @#$%^&*() 测试"
+ENCRYPTED=$(echo "$TEST_MSG" | ./build/otp-x86_64 encrypt ${PAD_CHKSUM:0:8})
+DECRYPTED=$(echo "$ENCRYPTED" | ./build/otp-x86_64 decrypt)
+
+if [ "$DECRYPTED" = "$TEST_MSG" ]; then
+    echo -e "${GREEN}✓ Special characters encryption/decryption successful${NC}"
+    ((TESTS_PASSED++))
+else
+    echo -e "${RED}✗ Special characters failed${NC}"
+    echo "  Expected: $TEST_MSG"
+    echo "  Got: $DECRYPTED"
+    ((TESTS_FAILED++))
+fi
+echo ""
+
+# Test 4: File encryption/decryption with padding
+echo "Test 4: File encryption/decryption"
+TEST_FILE="/tmp/otp_test_file.txt"
+echo "This is a test file for OTP encryption with padding." > "$TEST_FILE"
+
+./build/otp-x86_64 -f "$TEST_FILE" ${PAD_CHKSUM:0:8} -a -o /tmp/test_encrypted.otp.asc
+./build/otp-x86_64 decrypt /tmp/test_encrypted.otp.asc -o /tmp/test_decrypted.txt
+
+if diff "$TEST_FILE" /tmp/test_decrypted.txt > /dev/null 2>&1; then
+    echo -e "${GREEN}✓ File encryption/decryption successful${NC}"
+    ((TESTS_PASSED++))
+else
+    echo -e "${RED}✗ File encryption/decryption failed${NC}"
+    ((TESTS_FAILED++))
+fi
+
+# Cleanup
+rm -f "$TEST_FILE" /tmp/test_encrypted.otp.asc /tmp/test_decrypted.txt
+echo ""
+
+# Summary
+echo "=== Test Summary ==="
+echo -e "Tests passed: ${GREEN}${TESTS_PASSED}${NC}"
+echo -e "Tests failed: ${RED}${TESTS_FAILED}${NC}"
+echo ""
+
+if [ $TESTS_FAILED -eq 0 ]; then
+    echo -e "${GREEN}All tests passed!${NC}"
+    exit 0
+else
+    echo -e "${RED}Some tests failed.${NC}"
+    exit 1
+fi