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// A CommonCrypto-based implementation of RC4(tm)
//
// Authors:
// Sebastien Pouliot <sebastien@xamarin.com>
//
// (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright 2012-2014 Xamarin Inc.
using System;
using System.Security.Cryptography;
using Crimson.CommonCrypto;
#if MONOTOUCH || XAMMAC
using Mono.Security.Cryptography;
namespace Mono.Security.Cryptography {
#if !INSIDE_CORLIB
public
#endif
sealed partial class ARC4Managed : RC4, ICryptoTransform {
IntPtr handle;
public ARC4Managed ()
{
}
~ARC4Managed ()
{
Dispose (false);
}
#else
namespace Crimson.Security.Cryptography {
public abstract class RC4 : SymmetricAlgorithm {
private static KeySizes[] s_legalBlockSizes = {
new KeySizes (64, 64, 0)
};
private static KeySizes[] s_legalKeySizes = {
new KeySizes (40, 512, 8)
};
public RC4 ()
{
KeySizeValue = 128;
BlockSizeValue = 64;
FeedbackSizeValue = BlockSizeValue;
LegalBlockSizesValue = s_legalBlockSizes;
LegalKeySizesValue = s_legalKeySizes;
}
// required for compatibility with .NET 2.0
public override byte[] IV {
get { return new byte [0]; }
set { ; }
}
new static public RC4 Create()
{
return Create ("RC4");
}
new static public RC4 Create (string algName)
{
object o = CryptoConfig.CreateFromName (algName);
return (RC4) o ?? new RC4CommonCrypto ();
}
}
public sealed class RC4CommonCrypto : RC4, ICryptoTransform {
IntPtr handle;
public RC4CommonCrypto ()
{
}
~RC4CommonCrypto ()
{
Dispose (false);
}
#endif
public bool CanReuseTransform {
get { return false; }
}
public bool CanTransformMultipleBlocks {
get { return true; }
}
public int InputBlockSize {
get { return 1; }
}
public int OutputBlockSize {
get { return 1; }
}
public override byte[] Key {
get {
return base.Key;
}
set {
if (value == null)
throw new ArgumentNullException ("Key");
int length = (value.Length << 3);
KeySizeValue = length;
KeyValue = (byte[]) value.Clone ();
}
}
protected override void Dispose (bool disposing)
{
if (handle != IntPtr.Zero) {
Cryptor.CCCryptorRelease (handle);
handle = IntPtr.Zero;
}
base.Dispose (disposing);
GC.SuppressFinalize (this);
}
public override void GenerateIV ()
{
// not used for a stream cipher
IVValue = new byte [0];
}
public override void GenerateKey ()
{
KeyValue = KeyBuilder.Key (KeySizeValue >> 3);
}
public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV)
{
KeyValue = rgbKey;
IVValue = rgbIV;
return this;
}
public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV)
{
KeyValue = rgbKey;
IVValue = rgbIV;
return this;
}
private void CheckInput (byte[] inputBuffer, int inputOffset, int inputCount)
{
if (inputBuffer == null)
throw new ArgumentNullException ("inputBuffer");
if (inputOffset < 0)
throw new ArgumentOutOfRangeException ("inputOffset", "< 0");
if (inputCount < 0)
throw new ArgumentOutOfRangeException ("inputCount", "< 0");
// ordered to avoid possible integer overflow
if (inputOffset > inputBuffer.Length - inputCount)
throw new ArgumentException ("inputBuffer", "Overflow");
}
public unsafe int TransformBlock (byte[] inputBuffer, int inputOffset, int inputCount, byte[] outputBuffer, int outputOffset)
{
CheckInput (inputBuffer, inputOffset, inputCount);
if (inputCount == 0)
return 0;
// check output parameters
if (outputBuffer == null)
throw new ArgumentNullException ("outputBuffer");
if (outputOffset < 0)
throw new ArgumentOutOfRangeException ("outputOffset", "< 0");
// ordered to avoid possible integer overflow
if (outputOffset > outputBuffer.Length - inputCount)
throw new ArgumentException ("outputBuffer", "Overflow");
if (outputBuffer.Length == 0)
throw new CryptographicException ("output buffer too small");
if (handle == IntPtr.Zero)
handle = Cryptor.Create (CCOperation.Encrypt, CCAlgorithm.RC4, CCOptions.None, KeyValue, IVValue);
IntPtr len = IntPtr.Zero;
IntPtr in_len = (IntPtr) (inputBuffer.Length - inputOffset);
IntPtr out_len = (IntPtr) (outputBuffer.Length - outputOffset);
fixed (byte* input = &inputBuffer [0])
fixed (byte* output = &outputBuffer [0]) {
CCCryptorStatus s = Cryptor.CCCryptorUpdate (handle, (IntPtr) (input + inputOffset), in_len, (IntPtr) (output + outputOffset), out_len, ref len);
if ((len != out_len) || (s != CCCryptorStatus.Success))
throw new CryptographicUnexpectedOperationException (s.ToString ());
}
return (int) out_len;
}
public byte[] TransformFinalBlock (byte[] inputBuffer, int inputOffset, int inputCount)
{
CheckInput (inputBuffer, inputOffset, inputCount);
try {
byte[] output = new byte [inputCount];
TransformBlock (inputBuffer, inputOffset, inputCount, output, 0);
return output;
}
finally {
Cryptor.CCCryptorRelease (handle);
handle = IntPtr.Zero;
}
}
}
}
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