crypt

Crypt - Steganography CLI Tool

A CLI for steganography; focused on EAS, QRCode and DCT. Encryption and Decryption flows are supported.

Multiple methods fail to preserve the embedded information, after even a little compression. Here, a working "empirical" (opinionated?) workflow that survives heavy compression, is supported and proposed.

Steganography hides presence; once the carrier is suspect, AES does the confidentiality.

Threat model: be secretive. Then, if found out, still be safe. Live through extreme compression.

Example workflow:

flowchart LR
    %% ── FIRST LINE (HIDE) ──────────────────────────────
    subgraph "HIDE (crypt encrypt … embed)"
        direction LR
        plaintext["Plain text"] --> cipher["AES‑256‑GCM"] --> b64["Base64"] --> qr["QR encode"] --> bits["Binary bits"] --> stego["Stego JPEG"]
    end

    %% ── SECOND LINE (REVEAL) ───────────────────────────
    subgraph "REVEAL (crypt decrypt)"
        direction LR
        extract["Extract DCT"] --> qr2["QR decode"] --> b642["Base64"] --> decrypt["AES‑256‑GCM decrypt"] --> plain2["Plain text"]
    end

    %% ── VERTICAL LINK BETWEEN THE ROWS ────────────────
    stego --> extract

    %% ── OPTIONAL STYLING FOR THE CARRIER JPEG ─────────
    classDef carrier fill:#ffd5b3,stroke:#e49a46,stroke-width:1.5px,color:#000;
    class stego carrier;

crypt encrypt text q mysecurepassword qrcode binary embed "./test/input.jpeg" test/out_embedded.jpeg

crypt decrypt image ./test/out_embedded.jpeg extract text mysecurepassword

See the embedded sxiv ./test/out_embedded.jpeg. The secret is there and no image distortions!

Safezone

• Payload size ≈ 2 kB: QR Version 5‑L at 65 % JPEG quality is an empirical safezone.
• E.g., will be there after linkedin compresses your image in a tiny jpeg, for example.
• No authenticity yet: GCM gives you integrity only if the key is secret. If you switch to a stronger KDF, you're fine; otherwise add an HMAC.

Installation

Prerequisites

This project uses CGO with libjpeg for JPEG processing. You'll need to install the libjpeg development library:

Ubuntu/Debian:

sudo apt-get install libjpeg-dev

macOS:

brew install jpeg

Windows:

# Install via MSYS2 or use WSL
pacman -S mingw-w64-x86_64-libjpeg-turbo

Using go install (Recommended)

# Install the latest version
go install github.com/BuddhiLW/crypt/cmd/crypt@latest

# Or install a specific version
go install github.com/BuddhiLW/crypt/cmd/crypt@v1.0.0

Building from source

# Clone the repository
git clone https://github.com/BuddhiLW/crypt.git
cd crypt

# Use the installation script (recommended)
./scripts/install.sh

# Or build manually
go build -o crypt cmd/crypt/main.go

# Or install locally
go install ./cmd/crypt

Cross-platform builds

Note: Cross-compilation requires target-specific libjpeg libraries and may not work on all systems due to CGO dependencies.

# Build for all major platforms
make build-all

# Or build for specific platforms
make build-linux
make build-darwin
make build-windows

For reliable cross-platform builds, consider using Docker or building natively on each target platform.

Creating Releases

The project uses GoReleaser for automated releases. When you push a tag, it automatically:

1. Builds binaries for supported platforms
2. Creates GitHub releases
3. Generates checksums
4. Updates changelog

# Create a new release
git tag -a v1.0.0 -m "Release v1.0.0"
git push origin v1.0.0

# Or use the release script
./scripts/release.sh v1.0.0

# Suggest next version
./scripts/release.sh --suggest

# Show current version
./scripts/release.sh --current

Usage

# Get help
crypt help

# Encrypt data
crypt encrypt

# Decrypt data
crypt decrypt

Supported Platforms

• Linux (amd64, arm64)
• macOS (amd64, arm64)
• Windows (amd64, arm64)

Development

# Run tests
go test ./...

# Build and test locally
go build -o crypt cmd/crypt/main.go
./crypt help