Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Cryptography / DES.cs / 1 / DES.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // // DES.cs // namespace System.Security.Cryptography { using System; [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"); 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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