public static string Cipher(this string data, CypherMode mode)
{
var kdf2BytesGenerator = new Kdf2BytesGenerator(new Sha1Digest());
var kdfParameters = new KdfParameters(Key, Iv);
kdf2BytesGenerator.Init(kdfParameters);
var key = new byte[16];
kdf2BytesGenerator.GenerateBytes(key, 0, key.Length);
var engine = new AesLightEngine();
var blockCipher = new CbcBlockCipher(engine);
var cipher = new PaddedBufferedBlockCipher(blockCipher, new Pkcs7Padding());
var parameter = new KeyParameter(key);
var parameterWithIv = new ParametersWithIV(parameter, Iv, 0, 16);
var targetBytes = mode == CypherMode.Decryption
? Convert.FromBase64String(data)
: Encoding.UTF8.GetBytes(data);
cipher.Init(mode == CypherMode.Encryption, parameterWithIv);
var output = new byte[cipher.GetOutputSize(targetBytes.Length)];
var length = cipher.ProcessBytes(targetBytes, output, 0);
cipher.DoFinal(output, length);
return(mode == CypherMode.Encryption
? Convert.ToBase64String(output)
: Encoding.UTF8.GetString(output.Where(@byte => @byte != 0).ToArray()));
}
static byte[] Kdf2(byte[] sharedKeyBytes, byte[] ephemeralKeyBytes)
{
var gen = new Kdf2BytesGenerator(new Sha256Digest());
gen.Init(new KdfParameters(sharedKeyBytes, ephemeralKeyBytes));
byte[] encryptionKeyBytes = new byte[48];
gen.GenerateBytes(encryptionKeyBytes, 0, encryptionKeyBytes.Length);
return(encryptionKeyBytes);
}