PBKDFs

PBKDF stands for Password-Based Key Derivation Function. It is a type of algorithm used to transform a password or passphrase into a cryptographic key. The primary purpose of PBKDFs is to make it computationally expensive for attackers to guess passwords, even if they have obtained a database of stored password hashes.

PBKDFs work by repeatedly applying a cryptographic hash function to the password, often in conjunction with a salt. A salt is a unique, random value added to each password before hashing. This prevents attackers from using precomputed tables of common password hashes, known as rainbow tables. The iterative nature of PBKDFs means that a attacker would need to perform a large number of hash computations for each potential password, significantly slowing down brute-force attacks.

Several PBKDFs exist, each with different strengths and weaknesses. Common examples include PBKDF2, bcrypt, and scrypt. These algorithms often allow for adjustable parameters, such as the number of iterations or the memory cost, which can be tuned to balance security with performance requirements on the server. By increasing these parameters, the difficulty of cracking passwords also increases. PBKDFs are a crucial component in modern password security practices, used in many applications and systems to protect user credentials.