pbkdf2 provides a pure OCaml implementation of PBKDF2-HMAC-SHA256 as specified in RFC 8018. PBKDF2 derives cryptographic keys from passwords using a pseudorandom function (HMAC-SHA256), applying it iteratively to resist brute-force attacks.

Features#

RFC 8018 compliant: Implements PBKDF2-HMAC-SHA256
Configurable iterations: Control computational cost for security
Pure OCaml: No C dependencies, works everywhere OCaml runs
Fuzz tested: Includes Crowbar-based property tests

Installation#

opam install pbkdf2

Usage#

(* Derive a 32-byte key from a password *)
let key = Pbkdf2.derive
  ~password:"user_password"
  ~salt:random_salt
  ~iterations:100000
  ~length:32

API#

Pbkdf2.derive ~password ~salt ~iterations ~length - Derive a key using PBKDF2-HMAC-SHA256
Pbkdf2.hash_length - Output length of the underlying hash (32 bytes for SHA-256)

Security Recommendations#

Use at least 100,000 iterations for password hashing (OWASP recommendation)
Generate random salts of at least 16 bytes
Use unique salts per password

kdf - Key derivation functions including HKDF, PBKDF, and SCRYPT. Uses mirage-crypto for PBKDF2-SHA256.
pbkdf - PBKDF1/PBKDF2 implementation using nocrypto (archived, now part of kdf).

This library provides a minimal, standalone PBKDF2-HMAC-SHA256 implementation using digestif.

Licence#

MIT License. See LICENSE.md for details.

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pbkdf2#

Overview#