CyberGlossary

Cryptography

Argon2

Also known as: Argon2id, PHC winner

Definition

A modern memory-hard password hashing function and KDF, winner of the 2015 Password Hashing Competition and specified in RFC 9106.

Argon2 is a memory-hard key derivation and password hashing function designed by Biryukov, Dinu and Khovratovich, selected as the winner of the 2015 Password Hashing Competition and standardised in RFC 9106. It comes in three variants: Argon2d (data-dependent, fastest, side-channel-vulnerable), Argon2i (data-independent, resistant to side channels) and the recommended Argon2id (a hybrid). Tunable parameters include memory cost, time (iterations), parallelism and output length, with the memory-hardness making large-scale GPU/ASIC password cracking economically expensive. Argon2 is the recommended default for new password storage and KDF use cases; OWASP suggests Argon2id with at least 19 MiB of memory, t=2 and parallelism 1.

Examples

  • Storing user passwords using Argon2id with m=64 MiB, t=3, p=1.
  • Deriving a symmetric encryption key from a user passphrase in a disk-encryption tool.

Related terms