Overview of key derivation functions supported by OpenSSL

OpenSSL 3.0 supports several key derivation functions, but only two of them are suitable for deriving keys from passwords, namely, scrypt and PBKDF2.

PBKDF2 is a popular PBKDF, described and recommended by the PKCS #5 standard. It uses an HMAC function, such as HMAC-SHA-256, as an underlying PRF. PBKDF2 supports a tunable number of iterations and can be made computationally intensive, but not memory-intensive. In 2021, the Open Web Application Security Project (OWASP) recommended 310,000 iterations for PBKDF2 with the HMAC-SHA-256 PRF.

Scrypt is the best available choice for PBKDF in OpenSSL 3.0. Scrypt is a PBKDF that is not only computationally intensive but also memory-intensive. Scrypt uses PBKDF2 with HMAC-SHA-256 under the hood. Scrypt enables you to tune the volume of computations, memory usage, and parallelism. In 2021, OWASP recommended the following brute-force-resistant parameters for Scrypt: N=65,536, r=8,...