expand function
Derives a key, using the given pseudorandom key and optional context info, skipping the extraction step.
The prk should have been generated by extract, or be a uniformly random
or pseudorandom cryptographically strong key. See RFC 5869, Section 3.3.
Most common scenarios will want to use key instead.
Implementation
Uint8List expand({
required Uint8List prk,
required Uint8List info,
int length = 32,
}) => ffi.hkdfExpand(prk: prk, info: info, length: BigInt.from(length));