Argon2

Argon2 is a key derivation function that was selected as the winner of the 2015 Password Hashing Competition, designed by Alex Biryukov, Daniel Dinu, and Dmitry Khovratovich of the University of Luxembourg. It uses a large, fixed-size memory region to make brute-force attacks computationally expensive, and comes in three variants: Argon2d, which accesses memory in a password-dependent order to maximize resistance to GPU cracking; Argon2i, which accesses memory in a password-independent order to resist side-channel attacks; and Argon2id, a hybrid that follows the Argon2i approach for the first half-pass over memory and the Argon2d approach afterward. RFC 9106 recommends Argon2id where the difference between the variants is unclear or side-channel attacks are a viable threat, and all three variants are configured through parameters controlling execution time, memory required, and degree of parallelism.