passordfunksjon

A passordfunksjon, often translated as password function or password derivation function (PDF), is a cryptographic algorithm used to derive a cryptographic key from a password or passphrase. These functions are designed to be computationally intensive, meaning they require significant processing power and time to execute. This intentional slowness makes them resistant to brute-force attacks, where an attacker tries to guess the password by systematically trying many combinations.

The primary purpose of a passordfunksjon is to add a layer of security to encrypted data. Instead of directly using the password as an encryption key, which would be too short and predictable for strong encryption, the password is fed into the passordfunksjon. This function then generates a much longer, more complex key that is used for the actual encryption and decryption process. The computational cost ensures that even if an attacker obtains the encrypted data and the salt (a random value used to further complicate password hashing), they would still face a very difficult task in deriving the original password or key.

Common passordfunksjoner include PBKDF2 (Password-Based Key Derivation Function 2), bcrypt, and scrypt. Each of these functions employs different techniques to increase computational cost, such as iterative hashing, the use of a salt, and memory-hardness, which requires a significant amount of RAM. The choice of passordfunksjon and its parameters (like the number of iterations or memory cost) depends on the desired security level and the computational resources available.