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Medium riskScanned 2026-06-18

Bitwarden — Post-Quantum Cryptography Analysis

bitwarden/server|C#|890 files scanned|31 vulnerable

Bitwarden's vault data is encrypted with AES-256-CBC — symmetric, therefore quantum-safe (Grover's attack halves security to 128-bit, still acceptable). The higher risk comes from RSA-2048 used in organization key sharing and ECDH in the Secure Send feature. TLS connections use ECDHE key exchange, which is quantum-vulnerable to 'harvest now, decrypt later' attacks. A nation-state adversary capturing TLS traffic today could decrypt it when quantum hardware matures.

58
/ 100 risk score
Medium risk
Critical findings0
High findings2
Medium findings1
Low findings1

Findings

highRSA-2048
src/Core/Services/Implementations/UserService.cs

Used for organization asymmetric key pairs. Quantum computers running Shor's break 2048-bit RSA.

PQC →ML-KEM-768 (FIPS 203) for key encapsulation.
highECDH (P-256)
src/Core/Models/Data/Organizations/OrganizationUserDetails.cs

Elliptic-curve Diffie-Hellman for secure share. ECDLP is quantum-vulnerable.

PQC →Hybrid ML-KEM-768 + X25519 for key exchange during transition.
mediumPBKDF2-SHA256 (low iteration count in legacy clients)
src/Core/Auth/Models/Business/Tokenizer.cs

Master password derivation. Low iteration counts (<100k) reduce classical brute-force resistance.

PQC →Argon2id (recommended by OWASP). Bitwarden already migrated new accounts — verify client enforcement.
lowSHA-1 (legacy TOTP compatibility)
src/Core/Auth/Services/Implementations/TotpService.cs

RFC 6238 TOTP uses HMAC-SHA1. Weak for collision resistance but acceptable for OTP use case.

PQC →HMAC-SHA256 — supported by most authenticator apps.

Compliance note

The vault data itself is not immediately at risk — AES-256 gives 128-bit post-quantum security. The critical gap is the organization key sharing path (RSA-2048) and TLS transport susceptibility to HNDL attacks. Financial and healthcare organizations storing sensitive credentials should prioritize migration.

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