Phoenix: Rebirth of a Cryptographic Password-Hardening Service
summary
The scheme of Schneider et al. is shown vulnerable to offline dictionary attacks after a single validation query and even to full password extraction after one query, so external hardening fails there. A new construction PHOENIX uses a key-homomorphic PRF plus homomorphic encryption (no pairings), supports noninteractive key rotation of ciphertexts, and implements per-user counters for rate limiting. Benchmarks report ~8 ms added latency, ~370 auths/sec (single-core cloud), and throughput 50% faster than Schneider et al. and ~3x PYTHIA.
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chapters (13)
- 0:00Start
- 3:45Password Hunting Service
- 4:36Key Features of Partial Hardening Schemes
- 6:00Key Rotation
- 8:20Distributed Password Verification
- 14:38The Phoenix Ciphertext
- 15:18Why It Works
- 16:52Current Password Hardening Recommendations
- 19:40Deployment Issues
- 19:50Can We Combine Our Password Hardening Scheme with Memory Hard Functions
- 24:23Summary
- 26:33Key Rotation Migration
- 27:19Defense against Online Attacks
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