key function

Uint8List key({ required Uint8List password, required Uint8List salt, int time = 3, int memory = 65536, int threads = 4, int length = 32, })

Derives a key from the password, salt, and cost parameters using Argon2id returning a byte array that can be used as a cryptographic key. The CPU cost and parallelism degree must be greater than zero.

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

final key = argon2.key(password: password, salt: salt, time: 1, memory: 64*1024, threads: 4);

RFC 9106 Section 7.4 recommends time=1, and memory=2048*1024 as a sensible number. If using that amount of memory (2GB) is not possible in some contexts then the time parameter can be increased to compensate.

The time parameter specifies the number of passes over the memory and the memory parameter specifies the size of the memory in KiB. The number of threads can be adjusted to the numbers of available CPUs. The cost parameters should be increased as memory latency and CPU parallelism increases. Remember to get a good random salt.

Implementation

Uint8List key({
  required Uint8List password,
  required Uint8List salt,
  int time = 3,
  int memory = 65536,
  int threads = 4,
  int length = 32,
}) => ffi.argon2Key(
  password: password,
  salt: salt,
  time: time,
  memory: memory,
  threads: threads,
  keyLength: BigInt.from(length),
);