//
// System.Security.Cryptography SymmetricAlgorithm Class implementation
//
// Authors:
// Thomas Neidhart (tome@sbox.tugraz.at)
// Sebastien Pouliot <sebastien@ximian.com>
//
// Portions (C) 2002, 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2006 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System.Globalization;
using System.Runtime.InteropServices;
using Mono.Security.Cryptography;
namespace System.Security.Cryptography{
[ComVisible (true)]
public abstract class SymmetricAlgorithm : IDisposable {
protected int BlockSizeValue;
protected byte[] IVValue;
protected int KeySizeValue;
protected byte[] KeyValue;
protected KeySizes[] LegalBlockSizesValue;
protected KeySizes[] LegalKeySizesValue;
#if MOONLIGHT
// Silverlight 2.0 only supports CBC
internal int FeedbackSizeValue;
internal CipherMode ModeValue;
internal PaddingMode PaddingValue;
#else
protected int FeedbackSizeValue;
protected CipherMode ModeValue;
protected PaddingMode PaddingValue;
#endif
private bool m_disposed;
protected SymmetricAlgorithm ()
{
ModeValue = CipherMode.CBC;
PaddingValue = PaddingMode.PKCS7;
m_disposed = false;
}
#if MOONLIGHT
// No Finalizer or IDisposable.Dispose in Silverlight 2.0
// Documentation makes it "clear" that Clear MUST BE CALLED to zero out sensitive information
#else
~SymmetricAlgorithm ()
{
Dispose (false);
}
#endif
void IDisposable.Dispose ()
{
Dispose (true);
GC.SuppressFinalize (this); // Finalization is now unnecessary
}
public void Clear()
{
Dispose (true);
}
protected virtual void Dispose (bool disposing)
{
if (!m_disposed) {
// always zeroize keys
if (KeyValue != null) {
// Zeroize the secret key and free
Array.Clear (KeyValue, 0, KeyValue.Length);
KeyValue = null;
}
// dispose unmanaged managed objects
if (disposing) {
// dispose managed objects
}
m_disposed = true;
}
}
public virtual int BlockSize {
get { return this.BlockSizeValue; }
set {
if (!KeySizes.IsLegalKeySize (this.LegalBlockSizesValue, value)) {
throw new CryptographicException (
Locale.GetText ("block size not supported by algorithm"));
}
// re-setting the same BlockSize *doesn't* regenerate the IV
if (BlockSizeValue != value) {
BlockSizeValue = value;
IVValue = null;
}
}
}
public virtual int FeedbackSize {
get { return this.FeedbackSizeValue; }
set {
if ((value <= 0) || (value > this.BlockSizeValue)) {
throw new CryptographicException (
Locale.GetText ("feedback size larger than block size"));
}
this.FeedbackSizeValue = value;
}
}
public virtual byte[] IV {
get {
if (this.IVValue == null)
GenerateIV();
return (byte[]) this.IVValue.Clone ();
}
set {
if (value == null)
throw new ArgumentNullException ("IV");
// 2.0 is stricter for IV length - which is bad for IV-less stream ciphers like RC4
if ((value.Length << 3) != this.BlockSizeValue) {
throw new CryptographicException (
Locale.GetText ("IV length is different than block size"));
}
this.IVValue = (byte[]) value.Clone ();
}
}
public virtual byte[] Key {
get {
if (this.KeyValue == null)
GenerateKey();
return (byte[]) this.KeyValue.Clone ();
}
set {
if (value == null)
throw new ArgumentNullException ("Key");
int length = (value.Length << 3);
if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, length)) {
throw new CryptographicException (
Locale.GetText ("Key size not supported by algorithm"));
}
this.KeySizeValue = length;
this.KeyValue = (byte[]) value.Clone ();
}
}
public virtual int KeySize {
get { return this.KeySizeValue; }
set {
if (!KeySizes.IsLegalKeySize (this.LegalKeySizesValue, value)) {
throw new CryptographicException (
Locale.GetText ("Key size not supported by algorithm"));
}
// re-setting the same KeySize *does* regenerate the key
KeySizeValue = value;
KeyValue = null;
}
}
public virtual KeySizes[] LegalBlockSizes {
get { return this.LegalBlockSizesValue; }
}
public virtual KeySizes[] LegalKeySizes {
get { return this.LegalKeySizesValue; }
}
public virtual CipherMode Mode {
get { return this.ModeValue; }
set {
if (!Enum.IsDefined (ModeValue.GetType (), value)) {
throw new CryptographicException (
Locale.GetText ("Cipher mode not available"));
}
this.ModeValue = value;
}
}
public virtual PaddingMode Padding {
get { return this.PaddingValue; }
set {
if (!Enum.IsDefined (PaddingValue.GetType (), value)) {
throw new CryptographicException (
Locale.GetText ("Padding mode not available"));
}
this.PaddingValue = value;
}
}
public virtual ICryptoTransform CreateDecryptor ()
{
return CreateDecryptor (Key, IV);
}
public abstract ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV);
public virtual ICryptoTransform CreateEncryptor()
{
return CreateEncryptor (Key, IV);
}
public abstract ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV);
public abstract void GenerateIV ();
public abstract void GenerateKey ();
public bool ValidKeySize (int bitLength)
{
return KeySizes.IsLegalKeySize (LegalKeySizesValue, bitLength);
}
// LAMESPEC: Default is Rijndael - not TripleDES
public static SymmetricAlgorithm Create ()
{
return Create ("System.Security.Cryptography.SymmetricAlgorithm");
}
public static SymmetricAlgorithm Create (string algName)
{
return (SymmetricAlgorithm) CryptoConfig.CreateFromName (algName);
}
}
}
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