string Decrypt(string cipher)
{
int index = cipher.IndexOf('.');
string part1 = cipher.Remove(index);
string part2 = cipher.Substring(index + 1);
byte[] keyBytes = DecryptPkcs1(USED_KEY, Convert.FromBase64String(part1));
string result = Encoding.UTF8.GetString(DecryptTripleDES(keyBytes, Convert.FromBase64String(part2)));
return result;
}
byte[] DecryptPkcs1(string key, byte[] data)
{
if (data == null || data.Length == 0)
{
throw new NotSupportedException();
}
Pkcs1Encoding pkcs1Encoding = new Pkcs1Encoding(new RsaEngine());
RsaPrivateCrtKeyParameters parameters = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(key));
pkcs1Encoding.Init(false, parameters);
return pkcs1Encoding.ProcessBlock(data, 0, data.Length);
}
byte[] DecryptTripleDES(byte[] key, byte[] data)
{
byte[] rgbIV = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
Stream stream = new CryptoStream(new MemoryStream(data), new TripleDESCryptoServiceProvider
{
Mode = CipherMode.ECB,
Padding = PaddingMode.PKCS7
}.CreateDecryptor(key, rgbIV), CryptoStreamMode.Read);
byte[] array = new byte[data.Length];
stream.Read(array, 0, array.Length);
return array;
}
