docs/SECURITY.md

Security Guidelines - Crossword App

🔒 Environment Variables & API Keys

✅ Secure Practices Implemented

1. Environment Files

• ✅ .env files are gitignored
• ✅ .env.example template provided
• ✅ No real secrets in source code
• ✅ Automatic setup script provided

2. API Key Management

Local Development:

# 1. Set up environment
./setup-env.sh

# 2. Edit .env with your real key
HUGGINGFACE_API_KEY=hf_your_real_key_here

# 3. .env is automatically gitignored

Production Deployment:

• HuggingFace Spaces: Use Settings → Environment Variables
• Railway/Heroku: Use config vars
• Docker: Pass as runtime environment variables

3. Default Security

• 🛡️ Graceful fallback when API keys missing
• 🛡️ No crashes on missing configuration
• 🛡️ Warning messages instead of errors
• 🛡️ Safe defaults for all settings

🚨 What NOT to Do

❌ Never commit real API keys:

// ❌ NEVER DO THIS
const apiKey = 'hf_real_key_here';

❌ Never hardcode secrets:

// ❌ NEVER DO THIS
const config = {
  huggingfaceKey: 'hf_abcd1234...'
};

❌ Never share .env files:

# ❌ NEVER DO THIS
git add .env
git commit -m "added config"

✅ Safe Patterns

✅ Always use environment variables:

// ✅ SAFE
const apiKey = process.env.HUGGINGFACE_API_KEY;

✅ Always check for existence:

// ✅ SAFE WITH FALLBACK
if (!apiKey || apiKey === 'hf_xxxxxxxxxx') {
  console.warn('API key not configured, using fallback');
  return this.fallbackMethod();
}

✅ Always use templates:

# ✅ SAFE
cp .env.example .env
# Edit .env with real values

📁 File Security

Gitignore Coverage

# Environment files
.env
.env.local
.env.*.local

# Security files
*.key
*.pem
.secret
secrets/

File Structure

backend/
├── .env.example          # ✅ Safe template (committed)
├── .env                  # 🔒 Real values (gitignored)
├── .env.backup           # 🔒 Backup (gitignored)
└── setup-env.sh          # ✅ Setup script (committed)

🚀 Deployment Security

HuggingFace Spaces

1. Go to Space Settings
2. Add Environment Variable: HUGGINGFACE_API_KEY
3. Set value to your real API key
4. Restart space

Docker Deployment

# Runtime environment variable
docker run -e HUGGINGFACE_API_KEY=hf_your_key app

CI/CD Pipelines

# GitHub Actions example
env:
  HUGGINGFACE_API_KEY: ${{ secrets.HUGGINGFACE_API_KEY }}

🔍 Security Verification

Pre-commit Checklist

• No real API keys in code
• .env in .gitignore
• Only .env.example committed
• All secrets use environment variables
• Fallback mechanisms working

Testing Security

# Test without API key
unset HUGGINGFACE_API_KEY
npm run dev
# Should work with fallback

# Test with invalid key
export HUGGINGFACE_API_KEY="invalid"
npm run dev
# Should gracefully fallback

📚 Resources

• HuggingFace API Keys
• Environment Variable Best Practices
• Git Security Guidelines

🆘 If API Key Gets Exposed

1. Immediately revoke the key at https://huggingface.co/settings/tokens
2. Generate new key with appropriate permissions
3. Update all deployment environments
4. Check git history for any committed secrets
5. Consider repository security scan

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Remember: Security is a process, not a destination. Always be vigilant! 🛡️