/// <summary>
/// Transforms the specified region of the specified byte array.
/// </summary>
/// <param name="inputBuffer">The input for which to compute the transform.</param>
/// <param name="inputOffset">The offset into the byte array from which to begin using data.</param>
/// <param name="inputCount">The number of bytes in the byte array to use as data.</param>
/// <returns>The computed transform.</returns>
public byte[] TransformFinalBlock(byte[] inputBuffer, int inputOffset, int inputCount)
{
UInt64 block = ByteOperations.PackBytesIntoUInt64(inputBuffer, inputOffset);
// Call a function from the blowfish engine function.
if (Mode == BlowfishManagedTransformMode.Encrypt)
{
block = BlowfishEngine.Encrypt(block, Context);
}
if (Mode == BlowfishManagedTransformMode.Decrypt)
{
block = BlowfishEngine.Decrypt(block, Context);
}
return(ByteOperations.UnpackUInt64IntoBytes(block));
}
/// <summary>
/// Transforms the specified region of the input byte array and copies the resulting transform to the specified
/// region of the output byte array.
/// </summary>
/// <param name="inputBuffer">The input for which to compute the transform.</param>
/// <param name="inputOffset">The offset into the input byte array from which to begin using data.</param>
/// <param name="inputCount">The number of bytes in the input byte array to use as data.</param>
/// <param name="outputBuffer">The output to which to write the transform.</param>
/// <param name="outputOffset">The offset into the output byte array from which to begin writing data.</param>
/// <returns>The number of bytes written.</returns>
public int TransformBlock(byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
{
UInt64 block = ByteOperations.PackBytesIntoUInt64(inputBuffer, inputOffset);
// Call a function from the blowfish engine function.
if (Mode == BlowfishManagedTransformMode.Encrypt)
{
block = BlowfishEngine.Encrypt(block, Context);
}
if (Mode == BlowfishManagedTransformMode.Decrypt)
{
block = BlowfishEngine.Decrypt(block, Context);
}
byte[] TransformedBytes = ByteOperations.UnpackUInt64IntoBytes(block);
Array.Copy(TransformedBytes, 0, outputBuffer, outputOffset, TransformedBytes.Length);
return(TransformedBytes.Length);
}
/// <summary>
/// Creates a symmetric decryptor object with the specified Key property and initialization vector (IV).
/// </summary>
/// <param name="rgbKey"></param>
/// <param name="rgbIV"></param>
/// <returns></returns>
public override ICryptoTransform CreateDecryptor(byte[] rgbKey, byte[] rgbIV)
{
BlowfishContext encryptionContext = null;
if (ByteOperations.ArraysEqual(rgbKey, Key))
{
if (Context == null)
{
Context = new BlowfishContext(Key);
}
encryptionContext = Context;
}
else
{
encryptionContext = new BlowfishContext(rgbKey);
}
return(new BlowfishManagedTransform(encryptionContext, Mode, BlowfishManagedTransformMode.Decrypt));
}
/// <summary>
/// Decrypts a single block, running the 64 bits of data through all 16
/// rounds of the Blowfish algorithm. Returns the decrypted 64 bits.
/// </summary>
/// <param name="block64"></param>
/// <param name="Schedule"></param>
/// <returns></returns>
public static UInt64 Decrypt(UInt64 block64, BlowfishContext Context)
{
UInt32 left32 = ByteOperations.Left(block64);
UInt32 right32 = ByteOperations.Right(block64);
// We unrolled the Feistel loop, so the very first key XOR happens
// outside the loop here.
left32 ^= Context.Schedule.Get(17);
// 16 iterations of the Round function.
for (int i = 15; i >= 0; i -= 2)
{
right32 = Round(right32, left32, Context.Schedule.Get(i + 1), Context);
left32 = Round(left32, right32, Context.Schedule.Get(i), Context);
}
// Finalize the loop unrolling.
right32 = right32 ^ Context.Schedule.Get(0);
return(ByteOperations.Combine(right32, left32));
}
