Password-Based Key Derivation Function 2
In cryptography, PBKDF1 and PBKDF2 (Password-Based Key Derivation Function 2) are key derivation functions with a sliding computational cost, aimed to reduce the vulnerability of encrypted keys to brute force attacks.
PBKDF2 is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series, specifically PKCS #5 v2.0, also published as Internet Engineering Task Force's RFC 2898. It supersedes PBKDF1, which could only produce derived keys up to 160 bits long. RFC 8018, published in 2017, still recommends PBKDF2 for password hashing, even though newer password hashing functions such as Argon2 are designed to address weaknesses in older functions such as PBKDF2.