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//
// System.Security.Cryptography.DES
//
// Author:
// Sergey Chaban (serge@wildwestsoftware.com)
// Sebastien Pouliot <sebastien@ximian.com>
//
// Portions (C) 2002 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;
// References:
// a. FIPS PUB 46-3: Data Encryption Standard
// http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf
namespace System.Security.Cryptography {
#if NET_2_0
[ComVisible (true)]
#endif
public abstract class DES : SymmetricAlgorithm {
private const int keySizeByte = 8;
#if NET_2_0
protected DES ()
#else
public DES ()
#endif
{
KeySizeValue = 64;
BlockSizeValue = 64;
FeedbackSizeValue = 8;
LegalKeySizesValue = new KeySizes[1];
LegalKeySizesValue[0] = new KeySizes(64, 64, 0);
LegalBlockSizesValue = new KeySizes[1];
LegalBlockSizesValue[0] = new KeySizes(64, 64, 0);
}
public static new DES Create ()
{
return Create ("System.Security.Cryptography.DES");
}
public static new DES Create (string algo)
{
return (DES) CryptoConfig.CreateFromName (algo);
}
// Ek(Ek(m)) = m
internal static readonly byte[,] weakKeys = {
{ 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01 },
{ 0x1F, 0x1F, 0x1F, 0x1F, 0x0F, 0x0F, 0x0F, 0x0F },
{ 0xE1, 0xE1, 0xE1, 0xE1, 0xF1, 0xF1, 0xF1, 0xF1 },
{ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF },
};
// Ek1(Ek2(m)) = m
internal static readonly byte[,] semiWeakKeys = {
{ 0x00, 0x1E, 0x00, 0x1E, 0x00, 0x0E, 0x00, 0x0E }, // map to packed key 011F011F010E010E
{ 0x00, 0xE0, 0x00, 0xE0, 0x00, 0xF0, 0x00, 0xF0 }, // map to packed key 01E001E001F101F1
{ 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE }, // map to packed key 01FE01FE01FE01FE
{ 0x1E, 0x00, 0x1E, 0x00, 0x0E, 0x00, 0x0E, 0x00 }, // map to packed key 1F011F010E010E01
{ 0x1E, 0xE0, 0x1E, 0xE0, 0x0E, 0xF0, 0x0E, 0xF0 }, // map to packed key 1FE01FE00EF10EF1
{ 0x1E, 0xFE, 0x1E, 0xFE, 0x0E, 0xFE, 0x0E, 0xFE }, // map to packed key 1FFE1FFE0EFE0EFE
{ 0xE0, 0x00, 0xE0, 0x00, 0xF0, 0x00, 0xF0, 0x00 }, // map to packed key E001E001F101F101
{ 0xE0, 0x1E, 0xE0, 0x1E, 0xF0, 0x0E, 0xF0, 0x0E }, // map to packed key E01FE01FF10EF10E
{ 0xE0, 0xFE, 0xE0, 0xFE, 0xF0, 0xFE, 0xF0, 0xFE }, // map to packed key E0FEE0FEF1FEF1FE
{ 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00, 0xFE, 0x00 }, // map to packed key FE01FE01FE01FE01
{ 0xFE, 0x1E, 0xFE, 0x1E, 0xFE, 0x0E, 0xFE, 0x0E }, // map to packed key FE1FFE1FFE0EFE0E
{ 0xFE, 0xE0, 0xFE, 0xE0, 0xFE, 0xF0, 0xFE, 0xF0 }, // map to packed key FEE0FEE0FEF1FEF1
};
public static bool IsWeakKey (byte[] rgbKey)
{
#if NET_2_0
if (rgbKey == null)
throw new CryptographicException (Locale.GetText ("Null Key"));
#endif
if (rgbKey.Length != keySizeByte)
throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
// (fast) pre-check with "weak bytes"
for (int i=0; i < rgbKey.Length; i++) {
switch (rgbKey [i] | 0x11) {
case 0x11:
case 0x1F:
case 0xF1:
case 0xFF:
break;
default:
return false;
}
}
// compare with known weak keys
for (int i=0; i < (weakKeys.Length >> 3); i++) {
int j = 0;
for (; j < rgbKey.Length; j++) {
if ((rgbKey [j] ^ weakKeys [i,j]) > 1)
break;
}
if (j==8)
return true;
}
return false;
}
public static bool IsSemiWeakKey (byte[] rgbKey)
{
#if NET_2_0
if (rgbKey == null)
throw new CryptographicException (Locale.GetText ("Null Key"));
#endif
if (rgbKey.Length != keySizeByte)
throw new CryptographicException (Locale.GetText ("Wrong Key Length"));
// (fast) pre-check with "weak bytes"
for (int i=0; i < rgbKey.Length; i++) {
switch (rgbKey [i] | 0x11) {
case 0x11:
case 0x1F:
case 0xF1:
case 0xFF:
break;
default:
return false;
}
}
// compare with known weak keys
for (int i=0; i < (semiWeakKeys.Length >> 3); i++) {
int j = 0;
for (; j < rgbKey.Length; j++) {
if ((rgbKey [j] ^ semiWeakKeys [i,j]) > 1)
break;
}
if (j==8)
return true;
}
return false;
}
public override byte[] Key {
get {
if (KeyValue == null) {
// GenerateKey is responsible to return a valid key
// e.g. no weak or semi-weak keys
GenerateKey ();
}
return (byte[]) KeyValue.Clone ();
}
set {
if (value == null)
throw new ArgumentNullException ("Key");
if (value.Length != keySizeByte)
throw new ArgumentException (Locale.GetText ("Wrong Key Length"));
if (IsWeakKey (value))
throw new CryptographicException (Locale.GetText ("Weak Key"));
if (IsSemiWeakKey (value))
throw new CryptographicException (Locale.GetText ("Semi Weak Key"));
KeyValue = (byte[]) value.Clone ();
}
}
}
}
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