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PrivacyFirewall is a local-first PII and secrets firewall for AI tools like ChatGPT, Claude, and Gemini.It blocks risky paste events, warns as you type, and (optionally) uses a lightweight on-device Transformer model for deeper PII detection.

🔒 **No data ever leaves your machine.**Everything runs locally in your browser or through an optional local API.You can verify this by inspecting the network panel and reading the open-source code.

Modern AI tools make it extremely easy to leak sensitive information:

• Emails & phone numbers

• API keys & credentials

• Customer or employee data

• IP & MAC address

• Internal logs & stack traces

• Regulated personal information (PII/PHI)

Traditional enterprise DLP tools don’t cover AI chat prompts.

PrivacyFirewall adds a zero-trust privacy shield BEFORE your text ever reaches a third-party AI system.

• ✋ Human-in-the-loop protection for accidental leaks

• 🔒 100% local processing (browser + localhost only)

• ⚡ Practical protection (regex + optional transformer NER)

• 🧩 Friendly UX (warnings, paste-block modals, override options)

• 🛠 OSS and auditable (MV3 + FastAPI + Hugging Face stack)

1. **Lite Mode (regex-only)**Runs instantly in the extension — no setup needed.

2. **AI Mode (optional, local LLM)**Uses a local FastAPI agent + transformer model for deeper detection(People, organizations, locations, contextual entities).

graph TD
    A[User Pastes/Types Text]:::blueNode -->|Intercept| B(Chrome Extension):::blueNode
    B -->|Regex Check| C{Contains Secrets/PII?}
    C -->|Yes & Paste| D[BLOCK & WARN]:::redNode
    C -->|Yes & Typing| E[SHOW WARNING BANNER]:::redNode
    C -->|No| F{Local Engine Online?}
    F -->|No| G[Allow]:::blueNode
    F -->|Yes| H[Python Local Engine]:::blueNode
    H -->|BERT Model| I{AI Detected PII?}
    I -->|Yes & Paste| D
    I -->|Yes & Typing| E
    I -->|No| G

    classDef blueNode fill:#2563eb,stroke:#1e40af,color:#fff
    classDef redNode fill:#dc2626,stroke:#b91c1c,color:#fff

• Regex Mode covers secrets quickly

• AI Mode enhances detection when the local engine is running

• If the agent goes offline → extension falls back automatically

• Python 3.10+

• Chrome/Chromium/Edge

• Git

$ git clone https://github.com/privacyshield-ai/privacy-firewall.git

$ cd privacy-firewall

$ cd src/engine  python -m venv .venv  

$ source .venv/bin/activate       # Windows: .venv\Scripts\activate

$ pip install --upgrade 

$ pip install -r requirements.txt

$ uvicorn main:app --host 127.0.0.1 --port 8765   

• First run downloads dslim/bert-base-NER (~400MB) to ~/.cache/huggingface.

• http://127.0.0.1:8765/health → {"status":"ok"}

1. Visit: chrome://extensions

2. Enable Developer mode

3. Click Load unpacked

4. Select: src/extension/

You now have Lite Mode running with regex-based detection.

Go to:

• https://chat.openai.com

• https://claude.ai

• https://gemini.google.com

Paste:

My email is [email protected]   `

→ Paste is intercepted, modal appears.

Paste:

AKIAIOSFODNN7EXAMPLE

→ Detected as AWS key → blocked.

Enable AI Mode (when popup UI is ready), type:

 Meeting notes from Sarah Thompson at HR...   

→ Local transformer flags PERSON → warns you.

• Email address

• Phone number

• Credit card candidate

• MAC address

• IPv4 address

• AWS access keys

• JWT tokens

• Private key blocks

• Generic API key / hash patterns

• US SSN (basic pattern)

Powered by dslim/bert-base-NER:

• PERSON

• ORGANIZATION

• LOCATION

• Additional named entities

• Helpful for ambiguous or context-based leakage

src/extension/        Chrome MV3 extension (content script, background worker, UI assets)
src/engine/           FastAPI service + transformer model wrapper
src/engine/models/    Model utilities (Hugging Face pipeline)
src/engine/tests/     Basic test harness for detection

• HuggingFace models live in ~/.cache/huggingface/

• Delete this directory to force a fresh download

• Extension settings UI (enable/disable regex/AI modes)

• Add per-site allow/deny lists

• Add secret-type redaction instead of full block

• Package engine as a binary or desktop app

• Explore transformer.js for in-browser inference.

• Automated CI + browser testing

• Ensure the Python engine is running

• Confirm nothing else uses port 8765

• Lite mode will still block regex-based secrets

• Ensure AI Mode is enabled + engine is online

• NER models are probabilistic; long names work best

• Confidence threshold is tunable in transformer_detector.py

PRs and issues are welcome!Please include:

• OS & browser version

• Reproduction steps

• Model version (if reporting AI false positives/negatives)

• No prompts or text ever leave your machine

• Extension communicates only with:

  • Browser local context

  • Optional localhost API at 127.0.0.1:8765

• No analytics, telemetry, or external logging

• Review src/extension/content-script.js and DevTools → Network tabto verify behavior

MIT License.See LICENSE for full text.