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README.md
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@@ -1,51 +1,8 @@
# OTP Cipher - One Time Pad Implementation
## Quick Start
### Download Pre-Built Binaries
**[📥 Download Latest Release](https://git.laantungir.net/laantungir/otp/releases)**
Visit the releases page and download the appropriate binary for your system:
- `otp-vX.X.X-linux-x86_64` for Intel/AMD 64-bit systems
- `otp-vX.X.X-linux-arm64` for Raspberry Pi and ARM 64-bit systems
After downloading:
```bash
# Make executable and run
chmod +x otp-v*-linux-x86_64
./otp-v*-linux-x86_64
```
**Or use the local build:**
```bash
# After building from source
./build/otp-x86_64 # x86_64 systems
./build/otp-arm64 # ARM64 systems
```
### First Steps
1. **Generate your first pad:**
```bash
./build/otp-x86_64 generate 1GB
```
2. **Encrypt a message:**
```bash
./build/otp-x86_64 encrypt
# Follow the interactive prompts
```
3. **Decrypt a message:**
```bash
./build/otp-x86_64 decrypt
# Paste the encrypted message
```
## Introduction
A secure one-time pad (OTP) cipher implementation in C.
A secure one-time pad (OTP) cipher implementation in C99.
## Why One-Time Pads
@@ -83,8 +40,6 @@ To address this problem, we can use Nostr to share among devices the place in th
One-time pads can be trivially encrypted and decrypted using pencil and paper, making them accessible even without electronic devices.
## Features
- **Perfect Security**: Implements true one-time pad encryption with information-theoretic security
@@ -99,73 +54,102 @@ One-time pads can be trivially encrypted and decrypted using pencil and paper, m
- **Cross-Platform**: Works on Linux and other UNIX-like systems
## Building
## Quick Start
### Download Pre-Built Binaries
**[Download Current Linux x86](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.33/otp-v0.3.33-linux-x86_64)**
**[Download Current Raspberry Pi 64](https://git.laantungir.net/laantungir/otp/releases/download/v0.3.33/otp-v0.3.33-linux-arm64)**
After downloading:
```bash
# Rename for convenience, then make executable
mv otp-v0.3.33-linux-x86_64 otp
chmod +x otp
# Run it
./otp
```
### First Steps
1. **Generate your first pad:**
```bash
./otp generate 1GB
```
2. **Encrypt a message:**
```bash
./otp encrypt
# Follow the interactive prompts
```
3. **Decrypt a message:**
```bash
./otp decrypt
# Paste the encrypted message
```
## Building from Source
### Prerequisites
- GCC compiler
- Git (for version tracking)
- Make
- Optional: ARM64 cross-compiler (`gcc-aarch64-linux-gnu`) for cross-compilation
### Build Commands
Use the included build script for automatic versioning and cross-compilation:
```bash
# Build for current architecture (with auto-versioning)
./build.sh "commit message"
# Build commands
./build.sh build "commit message" # Build x86_64 and ARM64 (if cross-compiler available)
./build.sh clean # Clean build artifacts
./build.sh install # Install to system
./build.sh uninstall # Remove from system
```
The build script automatically:
- Increments patch version (v0.3.24 → v0.3.25)
- Creates git commit and tag
- Builds for x86_64 and ARM64 (if cross-compiler available)
- Outputs to `build/otp-x86_64` and `build/otp-arm64`
- Uploads binaries to Gitea releases (if `~/.gitea_token` exists)
### Traditional Make
You can also use make directly (without automatic versioning):
```bash
make # Build for current architecture
make static # Static linking
make clean # Clean artifacts
make static # Static linking (standalone binary)
make clean # Clean build artifacts
make install # Install to /usr/local/bin/otp
make uninstall # Remove from system
```
Output: `build/otp-$(ARCH)` (e.g., `build/otp-x86_64`)
## Usage
### Interactive Mode
After building, run with:
```bash
./build/otp-x86_64
# or
./build/otp-arm64 # On ARM systems
```
## Usage
The OTP Cipher operates in two modes:
**Interactive Mode**: Run without arguments to access a menu-driven interface. Best for exploring features, managing pads, and performing operations step-by-step with prompts and guidance.
**Command Line Mode**: Provide arguments to execute specific operations directly. Ideal for scripting, automation, and quick one-off tasks.
### Interactive Mode
Launch the menu-driven interface:
```bash
./otp
```
Navigate through menus to generate pads, encrypt/decrypt messages, manage pads, and configure settings.
### Command Line Mode
Execute operations directly with arguments:
```bash
# Generate a new pad
./build/otp-x86_64 generate 1GB
./otp generate 1GB
# Encrypt text (interactive input)
./build/otp-x86_64 encrypt <pad_hash_or_prefix>
# Encrypt text (will prompt for input)
./otp encrypt <pad_hash_or_prefix>
# Decrypt message (interactive input)
./build/otp-x86_64 decrypt <pad_hash_or_prefix>
# Decrypt message (will prompt for input)
./otp decrypt <pad_hash_or_prefix>
# List available pads
./build/otp-x86_64 list
./otp list
```
## Version System

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@@ -155,6 +155,45 @@ update_source_version() {
else
print_warning "src/main.h not found - skipping version update"
fi
# Update README.md with direct download links
if [ -f "README.md" ]; then
print_status "Updating README.md with download links for $NEW_VERSION..."
# Create the new download section with direct download links
local NEW_DOWNLOAD_SECTION="### Download Pre-Built Binaries
**[Download Current Linux x86](https://git.laantungir.net/laantungir/otp/releases/download/${NEW_VERSION}/otp-${NEW_VERSION}-linux-x86_64)**
**[Download Current Raspberry Pi 64](https://git.laantungir.net/laantungir/otp/releases/download/${NEW_VERSION}/otp-${NEW_VERSION}-linux-arm64)**
After downloading:
\`\`\`bash
# Rename for convenience, then make executable
mv otp-${NEW_VERSION}-linux-x86_64 otp
chmod +x otp
# Run it
./otp
\`\`\`"
# Use awk to replace the section between "### Download Pre-Built Binaries" and "### First Steps"
awk -v new_section="$NEW_DOWNLOAD_SECTION" '
/^### Download Pre-Built Binaries/ {
print new_section
skip=1
next
}
/^### First Steps/ {
skip=0
}
!skip
' README.md > README.md.tmp && mv README.md.tmp README.md
print_success "Updated README.md with download links for $NEW_VERSION"
else
print_warning "README.md not found - skipping README update"
fi
}
# Cross-platform build functions

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@@ -23,7 +23,7 @@
#include <ctype.h>
// Version - Updated automatically by build.sh
#define OTP_VERSION "v0.3.30"
#define OTP_VERSION "v0.3.33"
// Constants
#define MAX_INPUT_SIZE 4096

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@@ -89,18 +89,18 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
const char* pads_dir = get_current_pads_dir();
struct statvfs stat;
if (statvfs(pads_dir, &stat) == 0) {
// Use f_bfree (total free blocks) instead of f_bavail (available to non-root)
// This gives the actual free space on the filesystem, which is more accurate
// for removable media and user-owned directories
uint64_t available_bytes = stat.f_bfree * stat.f_frsize;
// Use f_bavail (available to non-root users) for accurate space reporting
// This accounts for filesystem reserved space (e.g., 5% on ext4)
uint64_t available_bytes = stat.f_bavail * stat.f_frsize;
double available_gb = (double)available_bytes / (1024.0 * 1024.0 * 1024.0);
double required_gb = (double)size_bytes / (1024.0 * 1024.0 * 1024.0);
if (available_bytes < size_bytes) {
printf("\n⚠ WARNING: Insufficient disk space!\n");
printf(" Required: %.2f GB\n", required_gb);
printf(" Available: %.2f GB\n", available_gb);
printf(" Required: %.2f GB (%lu bytes)\n", required_gb, size_bytes);
printf(" Available: %.2f GB (%lu bytes)\n", available_gb, available_bytes);
printf(" Shortfall: %.2f GB\n", required_gb - available_gb);
printf(" Location: %s\n", pads_dir);
printf("\nContinue anyway? (y/N): ");
char response[10];
@@ -129,11 +129,54 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
FILE* pad_file = fopen(temp_filename, "wb");
if (!pad_file) {
printf("Error: Cannot create temporary pad file %s\n", temp_filename);
printf("Error: Cannot create temporary pad file '%s': %s (errno %d)\n",
temp_filename, strerror(errno), errno);
fclose(urandom);
return 1;
}
// Preallocate full file size using posix_fallocate for guaranteed space reservation
// This actually allocates disk blocks (unlike ftruncate which creates sparse files)
int fd = fileno(pad_file);
double size_gb = (double)size_bytes / (1024.0 * 1024.0 * 1024.0);
if (display_progress) {
printf("Allocating %.2f GB on disk...\n", size_gb);
}
int alloc_result = posix_fallocate(fd, 0, (off_t)size_bytes);
if (alloc_result != 0) {
printf("Error: Failed to allocate %.2f GB temp file: %s (errno %d)\n",
size_gb, strerror(alloc_result), alloc_result);
printf(" Temp file: %s\n", temp_filename);
printf(" Location: %s\n", pads_dir);
if (alloc_result == ENOSPC) {
printf(" Cause: No space left on device\n");
printf(" This means the actual available space is less than reported\n");
} else if (alloc_result == EOPNOTSUPP) {
printf(" Cause: Filesystem doesn't support posix_fallocate\n");
printf(" Falling back to ftruncate (sparse file)...\n");
if (ftruncate(fd, (off_t)size_bytes) != 0) {
printf(" Fallback failed: %s\n", strerror(errno));
fclose(pad_file);
fclose(urandom);
unlink(temp_filename);
return 1;
}
} else {
printf(" Possible causes: quota limits, filesystem restrictions\n");
fclose(pad_file);
fclose(urandom);
unlink(temp_filename);
return 1;
}
}
if (display_progress && alloc_result == 0) {
printf("✓ Allocated %.2f GB on disk (guaranteed space)\n", size_gb);
}
unsigned char buffer[64 * 1024]; // 64KB buffer
uint64_t bytes_written = 0;
time_t start_time = time(NULL);
@@ -149,7 +192,8 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
}
if (fread(buffer, 1, (size_t)chunk_size, urandom) != (size_t)chunk_size) {
printf("Error: Failed to read from /dev/urandom\n");
printf("Error: Failed to read %lu bytes from /dev/urandom at position %lu: %s (errno %d)\n",
chunk_size, bytes_written, strerror(errno), errno);
fclose(urandom);
fclose(pad_file);
unlink(temp_filename);
@@ -157,7 +201,11 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
}
if (fwrite(buffer, 1, (size_t)chunk_size, pad_file) != (size_t)chunk_size) {
printf("Error: Failed to write to pad file\n");
printf("Error: fwrite failed for %lu bytes at position %lu/%lu (%.1f%%): %s (errno %d)\n",
chunk_size, bytes_written, size_bytes,
(double)bytes_written / size_bytes * 100.0, strerror(errno), errno);
printf(" Temp file: %s\n", temp_filename);
printf(" Disk space was checked - possible causes: fragmentation, I/O timeout, quota\n");
fclose(urandom);
fclose(pad_file);
unlink(temp_filename);
@@ -216,8 +264,10 @@ int generate_pad(uint64_t size_bytes, int display_progress) {
return 1;
}
double size_gb = (double)size_bytes / (1024.0 * 1024.0 * 1024.0);
printf("Generated pad: %s (%.2f GB)\n", pad_path, size_gb);
if (display_progress) {
double final_size_gb = (double)size_bytes / (1024.0 * 1024.0 * 1024.0);
printf("Generated pad: %s (%.2f GB)\n", pad_path, final_size_gb);
}
printf("Pad checksum: %s\n", chksum_hex);
printf("State file: %s\n", state_path);
printf("Pad file set to read-only\n");