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