scrypt

Documentation

Overview

Package scrypt implements the scrypt key derivation function as defined in Colin Percival's paper "Stronger Key Derivation via Sequential Memory-Hard Functions" (https://www.tarsnap.com/scrypt/scrypt.pdf).

Index

• func Key(password, salt []byte, N, r, p, keyLen int) ([]byte, error)

Functions

func Key

func Key(password, salt []byte, N, r, p, keyLen int) ([]byte, error)

Key derives a key from the password, salt, and cost parameters, returning a byte slice of length keyLen that can be used as cryptographic key.

N is a CPU/memory cost parameter, which must be a power of two greater than 1. r and p must satisfy r * p < 2³⁰. If the parameters do not satisfy the limits, the function returns a nil byte slice and an error.

For example, you can get a derived key for e.g. AES-256 (which needs a 32-byte key) by doing:

dk, err := scrypt.Key([]byte("some password"), salt, 32768, 8, 1, 32)

The recommended parameters for interactive logins as of 2017 are N=32768, r=8 and p=1. The parameters N, r, and p should be increased as memory latency and CPU parallelism increases; consider setting N to the highest power of 2 you can derive within 100 milliseconds. Remember to get a good random salt.