{"id":50486873,"url":"https://github.com/systemslibrarian/crypto-lab-j-uniward","last_synced_at":"2026-06-01T23:02:43.343Z","repository":{"id":351823220,"uuid":"1211993653","full_name":"systemslibrarian/crypto-lab-j-uniward","owner":"systemslibrarian","description":"Browser-based J-UNIWARD JPEG steganography demo — Daubechies-8 wavelet cost, full STC (h=12, 4096-state Viterbi), PBKDF2+HKDF key schedule, adaptive payload embedding, live steganalysis comparison. No backends. 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Implements the full pipeline from the 2013 Holub \u0026 Fridrich paper:\n\n- **Cost function:** Daubechies-8 three-level wavelet decomposition assigns a distortion cost to each DCT coefficient — changes in textured regions are \"cheaper.\"\n- **Embedding:** Full Syndrome-Trellis Code (STC, h=12, 4096 states) finds the minimum-distortion modification via Viterbi search (Filler, Judas \u0026 Fridrich 2011).\n- **Key schedule:** PBKDF2-SHA-256 (600k iterations) → HKDF domain separation → AES-CTR hat matrix + Fisher-Yates permutation. HMAC-SHA-256 integrity tag.\n- **Steganalysis:** Three-way comparison (LSB vs F5 vs J-UNIWARD) with chi-square PoV attack and DCT histogram visualization.\n\nEverything runs locally in your browser. No backends, no simulated math.\n\n## Quick Start\n\nClick **▶ Quick Demo** on the live site — it loads a sample image, prefills a message, and scrolls you straight to the embed step. Or follow the guided workflow:\n\n1. **Load** a sample image or upload your own JPEG\n2. **Enter** a secret message and shared key\n3. **Embed** with J-UNIWARD and watch the analysis panel compare three methods\n\n## Key Features\n\n| Feature | Description |\n|---------|-------------|\n| Adaptive placement | Changes land in high-texture DCT blocks — harder to detect |\n| Payload presets | Conservative (0.10), Balanced (0.20), Aggressive (0.40) bpnzac |\n| Embedding summary | Payload size, actual rate, carriers used, distortion, metadata status |\n| Visual comparison | Side-by-side cover/stego + 10× amplified difference map |\n| Live steganalysis | Chi-square p-value bars, DCT histograms, detectability labels |\n| Method explanations | Teaching text explains *why* each method is more or less detectable |\n| Image suitability | Indicator shows whether your image is a good or poor carrier |\n| Round-trip verification | Embed → download → upload → extract with integrity check |\n\n## Architecture\n\n```\nsrc/\n├── main.ts              # Thin orchestrator\n├── state/\n│   └── app-state.ts     # Central state\n├── ui/\n│   ├── theme.ts         # Dark/light toggle\n│   ├── dropzone.ts      # Image upload + samples\n│   ├── embed-panel.ts   # Embed tab + controls\n│   ├── extract-panel.ts # Extract tab\n│   ├── analysis-panel.ts# Steganalysis comparison\n│   └── renderers.ts     # Canvas drawing + alerts\n├── codec/\n│   └── JpegCodec.ts     # Custom JPEG DCT codec\n├── steg/\n│   ├── Embedder.ts      # J-UNIWARD embed\n│   ├── Extractor.ts     # STC extract\n│   └── WaveletCost.ts   # Daubechies-8 cost function\n├── analysis/\n│   └── StegAnalysis.ts  # Chi-square, histograms, comparison\n├── stc.ts               # STC Viterbi embed/extract\n├── stc-keys.ts          # AES-CTR hat matrix + permutation\n└── kdf.ts               # PBKDF2 + HKDF key derivation\n```\n\n## Limitations\n\n- **Simplified analysis.** The included chi-square test is a first-order statistical attack. Real-world steganalysis (SRNet, XuNet, etc.) uses deep learning on rich feature sets.\n- **COM marker sideband.** Salt and embedding rate are stored in a JPEG COM marker for extraction. This metadata may be stripped by image pipelines or social media compression.\n- **Not \"undetectable.\"** J-UNIWARD is *more resistant* than LSB/F5 under the included analysis — not invisible to all attacks.\n- **Educational tool.** This is a teaching and portfolio demo, not suitable for adversarial environments.\n\n## Run Locally\n\n```bash\ngit clone https://github.com/systemslibrarian/crypto-lab-j-uniward\ncd crypto-lab-j-uniward\nnpm install\nnpm run dev\n```\n\n## Live Demo\n\nhttps://systemslibrarian.github.io/crypto-lab-j-uniward/\n\n## Part of the Crypto-Lab Suite\n\nOne of 60+ live browser demos at [systemslibrarian.github.io/crypto-lab](https://systemslibrarian.github.io/crypto-lab/) — spanning Atbash (600 BCE) through NIST FIPS 203/204/205 (2024).\n\n---\n\n*\"Whether you eat or drink, or whatever you do, do all to the glory of God.\" — 1 Corinthians 10:31*\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fsystemslibrarian%2Fcrypto-lab-j-uniward","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fsystemslibrarian%2Fcrypto-lab-j-uniward","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fsystemslibrarian%2Fcrypto-lab-j-uniward/lists"}