hkdf static method
Implementation
static String hkdf({required String secret, String salt = "", String info = "", int length = 32, bool asHex = false}) {
final Uint8List dk = _hkdf(_sha256, _u8(secret), _u8(salt), _u8(info), length);
return asHex ? _toHex(dk) : base64.encode(dk);
}