Breach Check

Check if your email, phone or password has been in data breaches. Full security response workflow.

Check if email, phone, or password has appeared in known data breaches. Uses k-anonymity and privacy-preserving lookup, never sends raw credentials.

Workflow

1. Hash input — SHA-256 hash of email/phone. For passwords, use SHA-1 prefix (k-anonymity model, first 5 chars only sent).
2. Query breach DB — call Have I Been Pwned API v3 (or equivalent) with hash prefix. Respect rate limits (1.5s delay between calls).
3. Results — return only: breached (yes/no), breach name, data types exposed (email, password, phone, address, etc.).
   • Never return raw password or plaintext credential.
4. Severity triage:
   • 🔴 High — password exposed
   • 🟡 Medium — phone / address / ID number exposed
   • 🟢 Low — email-only breach
5. Action plan — per breach:
   • 🔴 → change password immediately, enable 2FA, check for account takeover
   • 🟡 → monitor for phishing, update linked account recovery info
   • 🟢 → review spam filter, update email alias if heavy spam
6. Password check — SHA-1 k-anonymity: send first 5 hex chars to Pwned Passwords API. Return count of occurrences.
7. Report — personal security report with:
   • breach timeline
   • severity summary
   • actionable todo list (prioritized)
8. Optional — set reminder for periodic re-check (cron / scheduling).

Sample Prompt

breach-check check --email [e-mail] --phone [phone]
breach-check password --check "my-p@ssw0rd"
breach-check monitor --email [e-mail] --interval monthly
breach-check report --email [e-mail] --format json