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// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// <OWNER>Microsoft</OWNER>
//
//
// DES.cs
//
namespace System.Security.Cryptography {
using System;
using System.Diagnostics.Contracts;
[System.Runtime.InteropServices.ComVisible(true)]
public abstract class DES : SymmetricAlgorithm
{
private static KeySizes[] s_legalBlockSizes = {
new KeySizes(64, 64, 0)
};
private static KeySizes[] s_legalKeySizes = {
new KeySizes(64, 64, 0)
};
//
// protected constructors
//
protected DES() {
KeySizeValue = 64;
BlockSizeValue = 64;
FeedbackSizeValue = BlockSizeValue;
LegalBlockSizesValue = s_legalBlockSizes;
LegalKeySizesValue = s_legalKeySizes;
}
//
// public properties
//
public override byte[] Key {
get {
if (KeyValue == null) {
// Never hand back a weak or semi-weak key
do {
GenerateKey();
} while (IsWeakKey(KeyValue) || IsSemiWeakKey(KeyValue));
}
return (byte[]) KeyValue.Clone();
}
set {
if (value == null) throw new ArgumentNullException("value");
Contract.EndContractBlock();
if (!ValidKeySize(value.Length * 8)) { // must convert bytes to bits
throw new ArgumentException(Environment.GetResourceString("Cryptography_InvalidKeySize"));
}
if (IsWeakKey(value)) {
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"DES");
}
if (IsSemiWeakKey(value)) {
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_SemiWeak"),"DES");
}
KeyValue = (byte[]) value.Clone();
KeySizeValue = value.Length * 8;
}
}
//
// public methods
//
new static public DES Create() {
return Create("System.Security.Cryptography.DES");
}
new static public DES Create(String algName) {
return (DES) CryptoConfig.CreateFromName(algName);
}
public static bool IsWeakKey(byte[] rgbKey) {
if (!IsLegalKeySize(rgbKey)) {
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize"));
}
byte[] rgbOddParityKey = Utils.FixupKeyParity(rgbKey);
UInt64 key = QuadWordFromBigEndian(rgbOddParityKey);
if ((key == 0x0101010101010101) ||
(key == 0xfefefefefefefefe) ||
(key == 0x1f1f1f1f0e0e0e0e) ||
(key == 0xe0e0e0e0f1f1f1f1)) {
return(true);
}
return(false);
}
public static bool IsSemiWeakKey(byte[] rgbKey) {
if (!IsLegalKeySize(rgbKey)) {
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize"));
}
byte[] rgbOddParityKey = Utils.FixupKeyParity(rgbKey);
UInt64 key = QuadWordFromBigEndian(rgbOddParityKey);
if ((key == 0x01fe01fe01fe01fe) ||
(key == 0xfe01fe01fe01fe01) ||
(key == 0x1fe01fe00ef10ef1) ||
(key == 0xe01fe01ff10ef10e) ||
(key == 0x01e001e001f101f1) ||
(key == 0xe001e001f101f101) ||
(key == 0x1ffe1ffe0efe0efe) ||
(key == 0xfe1ffe1ffe0efe0e) ||
(key == 0x011f011f010e010e) ||
(key == 0x1f011f010e010e01) ||
(key == 0xe0fee0fef1fef1fe) ||
(key == 0xfee0fee0fef1fef1)) {
return(true);
}
return(false);
}
//
// private methods
//
private static bool IsLegalKeySize(byte[] rgbKey) {
if (rgbKey != null && rgbKey.Length == 8) return(true);
return(false);
}
private static UInt64 QuadWordFromBigEndian(byte[] block)
{
UInt64 x;
x = (
(((UInt64)block[0]) << 56) | (((UInt64)block[1]) << 48) |
(((UInt64)block[2]) << 40) | (((UInt64)block[3]) << 32) |
(((UInt64)block[4]) << 24) | (((UInt64)block[5]) << 16) |
(((UInt64)block[6]) << 8) | ((UInt64)block[7])
);
return(x);
}
}
}
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