// Decode the specified byte array using CryptoAPITranform.
private static byte[] DecodeBytes(byte[] sourceBytes)
{
byte[] targetBytes = new byte[1024];
int currentPosition = 0;
// Create a DES decryptor from this instance to perform decryption.
CryptoAPITransform cryptoTransform =
(CryptoAPITransform)des.CreateDecryptor();
int inputBlockSize = cryptoTransform.InputBlockSize;
int sourceByteLength = sourceBytes.Length;
try
{
int numBytesRead = 0;
while (sourceByteLength - currentPosition >= inputBlockSize)
{
// Transform the bytes from current position in the
// sourceBytes array, writing the bytes to the targetBytes
// array.
numBytesRead = cryptoTransform.TransformBlock(
sourceBytes,
currentPosition,
inputBlockSize,
targetBytes,
currentPosition);
// Advance the current position in the source array.
currentPosition += numBytesRead;
}
// Transform the final block of bytes.
byte[] finalBytes = cryptoTransform.TransformFinalBlock(
sourceBytes,
currentPosition,
sourceByteLength - currentPosition);
// Copy the contents of the finalBytes array to the targetBytes
// array.
finalBytes.CopyTo(targetBytes, currentPosition);
}
catch (Exception ex)
{
Console.WriteLine("Caught unexpected exception:" + ex.ToString());
}
// Strip out the second block of bytes.
Array.Copy(targetBytes, (inputBlockSize * 2), targetBytes, inputBlockSize, targetBytes.Length - (inputBlockSize * 2));
// Trim the extra bytes in the array that were not used.
return(TrimArray(targetBytes));
}
/// <summary>
/// Extends TransformBlock so that buffer offset of 0 and call to Array.Length are not needed.
/// <example>
/// cryptoapitransform.TransformBlock(inputBuffer, outputBuffer, outputOffset);
/// </example>
/// </summary>
public static Int32 TransformBlock(this CryptoAPITransform cryptoapitransform, Byte[] inputBuffer, Byte[] outputBuffer, Int32 outputOffset)
{
if (cryptoapitransform == null)
{
throw new ArgumentNullException("cryptoapitransform");
}
if (inputBuffer == null)
{
throw new ArgumentNullException("inputBuffer");
}
return(cryptoapitransform.TransformBlock(inputBuffer, 0, inputBuffer.Length, outputBuffer, outputOffset));
}
// Encode the specified byte array by using CryptoAPITranform.
private static byte[] EncodeBytes(byte[] sourceBytes)
{
int currentPosition = 0;
byte[] targetBytes = new byte[1024];
int sourceByteLength = sourceBytes.Length;
// Create a DES encryptor from this instance to perform encryption.
CryptoAPITransform cryptoTransform =
(CryptoAPITransform)des.CreateEncryptor();
// Retrieve the block size to read the bytes.
int inputBlockSize = cryptoTransform.InputBlockSize;
// Retrieve the key handle.
IntPtr keyHandle = cryptoTransform.KeyHandle;
// Retrieve the block size to write the bytes.
int outputBlockSize = cryptoTransform.OutputBlockSize;
try
{
// Determine if multiple blocks can be transformed.
if (cryptoTransform.CanTransformMultipleBlocks)
{
int numBytesRead = 0;
while (sourceByteLength - currentPosition >= inputBlockSize)
{
// Transform the bytes from currentPosition in the
// sourceBytes array, writing the bytes to the targetBytes
// array.
numBytesRead = cryptoTransform.TransformBlock(
sourceBytes,
currentPosition,
inputBlockSize,
targetBytes,
currentPosition);
// Advance the current position in the sourceBytes array.
currentPosition += numBytesRead;
}
// Transform the final block of bytes.
byte[] finalBytes = cryptoTransform.TransformFinalBlock(
sourceBytes,
currentPosition,
sourceByteLength - currentPosition);
// Copy the contents of the finalBytes array to the
// targetBytes array.
finalBytes.CopyTo(targetBytes, currentPosition);
}
}
catch (Exception ex)
{
Console.WriteLine("Caught unexpected exception:" + ex.ToString());
}
// Determine if the current transform can be reused.
if (!cryptoTransform.CanReuseTransform)
{
// Free up any used resources.
cryptoTransform.Clear();
}
// Trim the extra bytes in the array that were not used.
return(TrimArray(targetBytes));
}