decrypt method
Implementation
Future<PrivateKey> decrypt(Uint8List keyphrase, Address addr, Uint8List salt,
{ScryptParams params}) async {
var addr58 = await addr.toBase58();
var dec = await Scrypt.decryptWithGcm(
encrypted: raw,
addr58: Convert.strToBytes(addr58),
salt: salt,
pwd: keyphrase,
params: params);
var key = PrivateKey(dec,
algorithm: algorithm, parameters: parameters, scrypt: params);
var pub = await key.getPublicKey();
var addrAct = await Address.fromPubkey(pub);
var addr58Act = await addrAct.toBase58();
if (addr58 != addr58Act) throw ArgumentError('Decrypt error');
return key;
}