public bool Encrypt(ref byte[] data, int length, ref byte[] tag)
{
if (IsInitialized)
{
_serverEncrypt.IV = BitConverter.GetBytes(_serverCounter).Combine(BitConverter.GetBytes(0x52565253));
using (IAuthenticatedCryptoTransform encryptor = _serverEncrypt.CreateAuthenticatedEncryptor())
{
data = encryptor.TransformFinalBlock(data, 0, length);
tag = encryptor.GetTag();
}
}
++_serverCounter;
return(true);
}
public void AuthenticatedAesCngChainingTest()
{
byte[] plaintext = new byte[20 * 1024];
byte[] iv = new byte[12];
byte[] authenticatedData = new byte[1024];
using (RNGCng rng = new RNGCng())
{
rng.GetBytes(plaintext);
rng.GetBytes(iv);
rng.GetBytes(authenticatedData);
}
foreach (CngChainingMode chainingMode in new CngChainingMode[] { CngChainingMode.Ccm, CngChainingMode.Gcm })
{
using (AuthenticatedAesCng aes = new AuthenticatedAesCng())
{
aes.AuthenticatedData = authenticatedData;
aes.CngMode = chainingMode;
aes.IV = iv;
// Encrypt the whole block of data at once
byte[] wholeCiphertext = null;
byte[] wholeTag = null;
using (IAuthenticatedCryptoTransform encryptor = aes.CreateAuthenticatedEncryptor())
{
wholeCiphertext = encryptor.TransformFinalBlock(plaintext, 0, plaintext.Length);
wholeTag = encryptor.GetTag();
}
// Encrypt it in chunks
byte[] blockCiphertext = null;
byte[] blockTag = null;
using (MemoryStream ms = new MemoryStream())
using (IAuthenticatedCryptoTransform encryptor = aes.CreateAuthenticatedEncryptor())
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
{
int chunkSize = 128;
for (int offset = 0; offset < plaintext.Length; offset += chunkSize)
{
cs.Write(plaintext, offset, chunkSize);
}
cs.FlushFinalBlock();
blockCiphertext = ms.ToArray();
blockTag = encryptor.GetTag();
}
// Make sure we got the same results in both cases
Assert.IsTrue(Util.CompareBytes(wholeCiphertext, blockCiphertext));
Assert.IsTrue(Util.CompareBytes(wholeTag, blockTag));
aes.Tag = wholeTag;
// Decrypt the whole block of data at once
using (ICryptoTransform decryptor = aes.CreateDecryptor())
{
byte[] wholePlaintext = decryptor.TransformFinalBlock(wholeCiphertext, 0, wholeCiphertext.Length);
Assert.IsTrue(Util.CompareBytes(plaintext, wholePlaintext));
}
// Decrypt the data in chunks
using (MemoryStream ms = new MemoryStream())
using (ICryptoTransform decryptor = aes.CreateDecryptor())
using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Write))
{
int chunkSize = 128;
for (int offset = 0; offset < blockCiphertext.Length; offset += chunkSize)
{
cs.Write(blockCiphertext, offset, chunkSize);
}
cs.FlushFinalBlock();
byte[] blockPlaintext = ms.ToArray();
Assert.IsTrue(Util.CompareBytes(plaintext, blockPlaintext));
}
}
}
}