datumbrain-plugins

Claude Privacy Guard

🛡️ Prevent secrets and PII from being accidentally shared with Claude Code.

A privacy-first plugin for Claude Code that scans prompts for sensitive data and blocks them before they reach the AI.

Features

• ✅ Blocks prompts containing sensitive data before they're sent to Claude
• ✅ Detects PII, secrets, API keys, tokens, and sensitive information
• ✅ Works locally - all scanning happens on your machine
• ✅ Zero configuration - works out of the box
• ✅ Detailed reporting - shows exactly what was detected

Installation

# Add the marketplace (if not already added)
/plugin marketplace add datumbrain/claude-privacy-guard

# Install the plugin
/plugin install claude-privacy-guard

⚠️ Important: Restart Required

After installing the plugin, you must restart your Claude Code session for it to take effect. This is because hooks are registered at session startup - Claude Code doesn't dynamically load new hooks mid-session.

Simply close and reopen Claude Code, or start a new session.

Once restarted, the plugin will automatically scan all prompts before they reach Claude.

What Gets Detected

✅ Secrets

• OpenAI API keys (sk-..., sk-proj-...)
• AWS credentials
• GitHub tokens
• Stripe keys
• JWT tokens
• Bearer tokens
• SSH private keys
• Generic API key patterns

✅ Personal Information (PII)

• Email addresses
• Phone numbers
• Social Security Numbers
• Credit card numbers

How It Works

1. You type a prompt in Claude Code
2. Privacy Guard intercepts it via a UserPromptSubmit hook
3. Scans for sensitive data using regex patterns
4. Blocks the prompt if sensitive data is found
5. Shows you exactly what was detected

Example

Input:

My API key is sk-proj-abc123xyz and email is [email protected]

Result:

🛡️ Privacy Guard blocked this prompt

Found 2 sensitive item(s):
  - API_KEY: sk-proj-abc123xyz...
  - EMAIL: [email protected]...

Risk Score: 100/100
Secrets: 1 | PII: 1

Please remove or anonymize sensitive data before proceeding.

Development

# Clone the repository
git clone https://github.com/datumbrain/claude-privacy-guard.git
cd claude-privacy-guard

# Install dependencies
npm install

# Build
npm run build

# Test the scanner directly
echo "test sk-proj-abc123" | node scripts/prompt-guard.js

Release:

make release

This runs an interactive flow that asks for version bump, confirms release actions, then runs build/test, creates commit+tag, and optionally pushes/publishes.

External regex dataset:

• Converted rules are stored at data/regex_list_1.json
• By default, external rules are loaded in coding-only mode (focus on keys/tokens/secrets/password/private key patterns)
• Set .privacy-guard.json to control behavior:

{
  "externalRulesJsonPath": "./data/regex_list_1.json",
  "externalRulesMode": "coding-only"
}

See docs/ for detailed architecture and integration guides.

Privacy & Security

• ✅ All scanning happens locally on your machine
• ✅ No data is sent to external services
• ✅ No telemetry or tracking
• ✅ Open source and fully auditable
• ✅ The plugin only blocks - it doesn't store or log your sensitive data

Why Block Instead of Redact?

Claude Code's hook system doesn't support transforming prompts - only blocking or adding context. Blocking ensures sensitive data never reaches the AI, which is the safest approach.

Debugging

Check the debug log if you encounter issues:

cat /tmp/claude-privacy-guard.log

Contributing

Contributions welcome! Please feel free to submit a Pull Request.

License

MIT © Datum Brain