Glossary · Cryptography & authentication
Argon2id
Argon2id is the recommended variant of Argon2, winner of the Password Hashing Competition: a memory-hard key-derivation function that makes password guessing expensive on GPUs and custom hardware, while resisting side-channel attacks.
Argon2 comes in three variants: Argon2d (fastest, data-dependent memory access, side-channel sensitive), Argon2i (data-independent access), and Argon2id, which runs the first pass independent and the rest dependent — the practical default recommended by RFC 9106 and OWASP.
Memory-hardness is the point: each guess requires holding tens of megabytes, so an attacker cannot pack thousands of parallel attempts onto a GPU the way they can against SHA-based PBKDF2. Parameters (memory, iterations, parallelism) are tuned to the slowest acceptable legitimate login.
Ciphera ID runs Argon2id client-side when stretching account secrets — the cost is paid in the user’s browser, and what leaves the device is already high-entropy key material.