Add CI/CD workflows and security policy
This commit is contained in:
Aaron D. Lee
237
SECURITY.md
Normal file
237
SECURITY.md
Normal file
@@ -0,0 +1,237 @@
|
||||
# Security Policy
|
||||
|
||||
## Supported Versions
|
||||
|
||||
| Version | Supported |
|
||||
| ------- | ------------------ |
|
||||
| 2.x.x | :white_check_mark: |
|
||||
| 1.x.x | :x: |
|
||||
|
||||
## Reporting a Vulnerability
|
||||
|
||||
**Please do not report security vulnerabilities through public GitHub issues.**
|
||||
|
||||
Instead, please email: **security@example.com** (replace with your email)
|
||||
|
||||
Include:
|
||||
- Description of the vulnerability
|
||||
- Steps to reproduce
|
||||
- Potential impact
|
||||
- Any suggested fixes
|
||||
|
||||
You should receive a response within 48 hours. We'll work with you to understand and address the issue.
|
||||
|
||||
---
|
||||
|
||||
# Threat Model
|
||||
|
||||
## What Stegasoo Protects
|
||||
|
||||
Stegasoo is designed to hide the **existence** of a secret message within an ordinary-looking image, protected by multi-factor authentication.
|
||||
|
||||
### Protection Goals
|
||||
|
||||
| Goal | How It's Achieved |
|
||||
|------|-------------------|
|
||||
| **Confidentiality** | AES-256-GCM encryption with Argon2id key derivation |
|
||||
| **Steganography** | LSB embedding with pseudo-random pixel selection |
|
||||
| **Authentication** | Multi-factor: reference photo + passphrase + PIN (or RSA key) |
|
||||
| **Integrity** | GCM authentication tag detects tampering |
|
||||
|
||||
### Security Factors
|
||||
|
||||
Stegasoo combines multiple authentication factors:
|
||||
|
||||
```
|
||||
┌─────────────────────────────────────────────────────────────┐
|
||||
│ Key Derivation │
|
||||
│ │
|
||||
│ Reference Photo ─────┐ │
|
||||
│ (something you have) │ │
|
||||
│ ├──► Argon2id ──► AES-256 Key │
|
||||
│ Day Passphrase ──────┤ (256MB RAM) │
|
||||
│ (something you know) │ │
|
||||
│ │ │
|
||||
│ PIN or RSA Key ──────┘ │
|
||||
│ (second factor) │
|
||||
└─────────────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## What Stegasoo Does NOT Protect Against
|
||||
|
||||
### 1. Statistical Steganalysis
|
||||
|
||||
**Risk:** Advanced analysis can detect that an image contains hidden data.
|
||||
|
||||
**Reality:** LSB steganography is detectable by:
|
||||
- Chi-square analysis
|
||||
- RS analysis
|
||||
- Machine learning classifiers
|
||||
|
||||
**Mitigation:** Stegasoo uses pseudo-random pixel selection (not sequential), which helps but doesn't eliminate detectability.
|
||||
|
||||
**Recommendation:** Don't rely on Stegasoo if your adversary has:
|
||||
- Access to the original carrier image
|
||||
- Sophisticated forensic tools
|
||||
- Motivation to analyze your specific images
|
||||
|
||||
### 2. Compromised Endpoints
|
||||
|
||||
**Risk:** If your device is compromised, the attacker can capture credentials.
|
||||
|
||||
**Not protected:**
|
||||
- Keyloggers capturing your PIN/passphrase
|
||||
- Screen capture of decoded messages
|
||||
- Memory scraping during encode/decode
|
||||
- Malware on sender or receiver device
|
||||
|
||||
**Recommendation:** Use on trusted devices only.
|
||||
|
||||
### 3. Reference Photo Exposure
|
||||
|
||||
**Risk:** The reference photo is a critical secret.
|
||||
|
||||
**If leaked:** Attacker only needs to guess/brute-force the passphrase + PIN.
|
||||
|
||||
**Recommendation:**
|
||||
- Never share the reference photo
|
||||
- Use a unique photo (not posted online)
|
||||
- Store securely (encrypted drive, password manager)
|
||||
|
||||
### 4. Weak Credentials
|
||||
|
||||
**Risk:** Short PINs or common passphrases can be brute-forced.
|
||||
|
||||
| PIN Length | Combinations | Time to Brute Force* |
|
||||
|------------|--------------|----------------------|
|
||||
| 4 digits | 10,000 | Seconds |
|
||||
| 6 digits | 1,000,000 | Minutes |
|
||||
| 8 digits | 100,000,000 | Hours |
|
||||
| 9 digits | 1,000,000,000| Days |
|
||||
|
||||
*With Argon2 (256MB RAM, 4 iterations), each attempt takes ~1 second, making brute force slow but not impossible for short PINs.
|
||||
|
||||
**Recommendation:**
|
||||
- Use 8+ digit PINs
|
||||
- Use 4+ word passphrases
|
||||
- Consider RSA keys for high-security use cases
|
||||
|
||||
### 5. Image Modification
|
||||
|
||||
**Risk:** Lossy compression destroys hidden data.
|
||||
|
||||
**Data is destroyed by:**
|
||||
- JPEG compression
|
||||
- Resizing
|
||||
- Filters/effects
|
||||
- Screenshots
|
||||
- Social media upload (Instagram, Twitter, etc.)
|
||||
|
||||
**Recommendation:**
|
||||
- Always use lossless formats (PNG, BMP)
|
||||
- Transfer files directly (email, Signal, USB)
|
||||
- Never upload stego images to social media
|
||||
|
||||
### 6. Metadata Leakage
|
||||
|
||||
**Risk:** The stego image itself may reveal information.
|
||||
|
||||
**Potential leaks:**
|
||||
- File creation timestamp
|
||||
- Camera EXIF data (if carrier has it)
|
||||
- File size changes
|
||||
|
||||
**Mitigation:** Stegasoo strips EXIF on output, but timestamps remain.
|
||||
|
||||
### 7. Traffic Analysis
|
||||
|
||||
**Risk:** The act of sending an image may be suspicious.
|
||||
|
||||
**Not protected:**
|
||||
- Network observers seeing you send image files
|
||||
- Email metadata showing sender/receiver
|
||||
- Frequency analysis of communications
|
||||
|
||||
**Recommendation:** Use alongside normal image-sharing behavior.
|
||||
|
||||
## Cryptographic Details
|
||||
|
||||
### Encryption
|
||||
|
||||
| Component | Algorithm | Parameters |
|
||||
|-----------|-----------|------------|
|
||||
| Key Derivation | Argon2id | 256MB RAM, 4 iterations, 4 parallelism |
|
||||
| Fallback KDF | PBKDF2-SHA256 | 600,000 iterations |
|
||||
| Encryption | AES-256-GCM | 12-byte IV, 16-byte tag |
|
||||
| Photo Hash | SHA-256 | Full image bytes |
|
||||
|
||||
### Pixel Selection
|
||||
|
||||
Pixels are selected pseudo-randomly using a key derived from:
|
||||
```
|
||||
pixel_key = SHA256(photo_hash || passphrase || date || pin/rsa_signature)
|
||||
```
|
||||
|
||||
This prevents:
|
||||
- Sequential embedding patterns
|
||||
- Statistical detection of modified regions
|
||||
|
||||
### Format
|
||||
|
||||
```
|
||||
┌──────────────────────────────────────────────────────────────┐
|
||||
│ Magic (4B) │ Version (1B) │ Date (10B) │ Salt (32B) │ IV (12B) │
|
||||
├──────────────────────────────────────────────────────────────┤
|
||||
│ Encrypted Payload (AES-256-GCM) │
|
||||
│ ├── Type (1B): 0x01=text, 0x02=file │
|
||||
│ ├── Length (4B) │
|
||||
│ ├── Data (variable) │
|
||||
│ └── [Filename if file] (variable) │
|
||||
├──────────────────────────────────────────────────────────────┤
|
||||
│ GCM Auth Tag (16B) │
|
||||
└──────────────────────────────────────────────────────────────┘
|
||||
```
|
||||
|
||||
## Best Practices
|
||||
|
||||
### For Maximum Security
|
||||
|
||||
1. **Use RSA keys** instead of PINs for authentication
|
||||
2. **Use unique reference photos** not available online
|
||||
3. **Use long passphrases** (4+ random words)
|
||||
4. **Transfer via secure channels** (Signal, encrypted email)
|
||||
5. **Delete stego images** after message is read
|
||||
6. **Keep software updated** for security fixes
|
||||
|
||||
### For Casual Privacy
|
||||
|
||||
1. **6-digit PIN** is sufficient for non-adversarial use
|
||||
2. **3-word passphrase** provides reasonable security
|
||||
3. **PNG format** always for output
|
||||
4. **Direct file transfer** (email attachment, AirDrop)
|
||||
|
||||
## Known Limitations
|
||||
|
||||
| Limitation | Impact | Status |
|
||||
|------------|--------|--------|
|
||||
| LSB is detectable | Statistical analysis can detect hidden data | By design (tradeoff for capacity) |
|
||||
| No forward secrecy | Compromised key decrypts all messages | Use different keys per message for high security |
|
||||
| Date in header | Reveals when message was encoded | By design (enables day-specific passphrases) |
|
||||
| No deniability | Single password = single message | Future: plausible deniability layers |
|
||||
|
||||
## Security Audit Status
|
||||
|
||||
This software has **not** been professionally audited. Use at your own risk for sensitive applications.
|
||||
|
||||
If you're a security researcher interested in auditing Stegasoo, please reach out.
|
||||
|
||||
---
|
||||
|
||||
## Version History (Security Relevant)
|
||||
|
||||
| Version | Security Changes |
|
||||
|---------|------------------|
|
||||
| 2.2.0 | Added compression (no security impact) |
|
||||
| 2.1.0 | Upgraded to Argon2id, increased iterations |
|
||||
| 2.0.0 | Added RSA key support |
|
||||
| 1.0.0 | Initial release |
|
||||
Reference in New Issue
Block a user