decrypt method
Implementation
Uint8List decrypt(Uint8List cipherText, Uint8List iv) {
final cipher = pointy.GCMBlockCipher(pointy.AESEngine())
..init(
false, // decrypt
pointy.AEADParameters(
pointy.KeyParameter(_key), // the 256 bit (32 byte) key
128, //Mac length
iv, // the 12 byte nonce
Uint8List(0), // empty extra data
));
return cipher.process(cipherText);
}