public byte[] TransformFinalBlock(byte[] input, int inputOffset, int count)
{
ulong ivLength = this.iv == null ? 0 : (ulong)this.iv.Length;
uint result;
ulong outputSize;
// Get the required size of the plaintext/ciphertext buffer
if (this.isEncrypting)
{
result = BCryptCore.BCryptEncrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, null, 0, out outputSize, BCryptConstants.BCRYPT_BLOCK_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered while retrieving the ciphertext size.");
}
}
else
{
result = BCryptCore.BCryptDecrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, null, 0, out outputSize, BCryptConstants.BCRYPT_BLOCK_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered while retrieving the plaintext size.");
}
}
byte[] output = new byte[outputSize];
// No padding is used with authenticatied modes
// Bypass final block transformation and defer to regular transformation
if (this.mode == BlockCipherMode.GCM || this.mode == BlockCipherMode.CCM)
{
this.TransformBlock(input, inputOffset, output, 0, count);
return(output);
}
ulong pcbResult;
if (this.isEncrypting)
{
result = BCryptCore.BCryptEncrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, output, (ulong)output.Length, out pcbResult, BCryptConstants.BCRYPT_BLOCK_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered during encryption.");
}
}
else
{
result = BCryptCore.BCryptDecrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, output, (ulong)output.Length, out pcbResult, BCryptConstants.BCRYPT_BLOCK_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered during decryption.");
}
}
return(output);
}
public static void SetBlockChainingMode(IntPtr hAlgorithmProvider, BlockCipherMode mode)
{
string chainingModeValue;
switch (mode)
{
case BlockCipherMode.CBC:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_CBC;
break;
case BlockCipherMode.CCM:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_CCM;
break;
case BlockCipherMode.CFB:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_CFB;
break;
case BlockCipherMode.ECB:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_ECB;
break;
case BlockCipherMode.GCM:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_GCM;
break;
case BlockCipherMode.Unspecified:
chainingModeValue = BCryptConstants.BCRYPT_CHAIN_MODE_NA;
break;
default:
throw new ArgumentException("The specified block cipher chaining mode is not recognized.", nameof(mode));
}
GCHandle gcChainingModeValue = GCHandle.Alloc(chainingModeValue, GCHandleType.Pinned);
uint result;
try
{
result = BCryptCore.BCryptSetProperty(hAlgorithmProvider, BCryptConstants.BCRYPT_CHAINING_MODE, gcChainingModeValue.AddrOfPinnedObject(), (ulong)chainingModeValue.Length, 0);
}
finally
{
gcChainingModeValue.Free();
}
if (result != 0)
{
throw new SystemException("An error was encountered while setting the cipher chaining mode.");
}
}
public void TransformBlock(byte[] input, int inputOffset, byte[] output, int outputOffset, int count)
{
ulong pcbResult;
ulong ivLength = this.iv == null ? 0 : (ulong)this.iv.Length;
if (this.isEncrypting)
{
uint result = BCryptCore.BCryptEncrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, output, (ulong)output.Length, out pcbResult, BCryptConstants.BCRYPT_NO_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered during encryption.");
}
}
else
{
uint result = BCryptCore.BCryptDecrypt(this.hKey, input, (ulong)count, IntPtr.Zero, this.iv, ivLength, output, (ulong)output.Length, out pcbResult, BCryptConstants.BCRYPT_NO_PADDING);
if (result != 0)
{
throw new SystemException("An error was encountered during decryption.");
}
}
}
public BCryptAesTransformer(BlockCipherMode mode, byte[] key, byte[] iv, bool isEncrypting)
{
this.mode = mode;
uint result = BCryptCore.BCryptOpenAlgorithmProvider(out this.hAlgorithmProvider, "AES", null, 0);
if (result != 0)
{
throw new SystemException("An error was encountered while opening the algorithm provider.");
}
BCryptHelper.SetBlockChainingMode(this.hAlgorithmProvider, mode);
result = BCryptCore.BCryptGenerateSymmetricKey(this.hAlgorithmProvider, out this.hKey, null, 0, key, (ulong)key.Length, 0);
if (result != 0)
{
throw new SystemException("An error was encountered while generating a symmetric key.");
}
this.iv = iv;
this.isEncrypting = isEncrypting;
}
protected virtual void Dispose(bool disposing)
{
BCryptCore.BCryptDestroyKey(this.hKey);
BCryptCore.BCryptCloseAlgorithmProvider(this.hAlgorithmProvider, 0);
}
