Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Cryptography / TripleDES.cs / 1 / TripleDES.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== // // TripleDES.cs // namespace System.Security.Cryptography { [System.Runtime.InteropServices.ComVisible(true)] public abstract class TripleDES : SymmetricAlgorithm { private static KeySizes[] s_legalBlockSizes = { new KeySizes(64, 64, 0) }; private static KeySizes[] s_legalKeySizes = { new KeySizes(2*64, 3*64, 64) }; // // protected constructors // protected TripleDES() { KeySizeValue = 3*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 key do { GenerateKey(); } while (IsWeakKey(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 CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize")); } if (IsWeakKey(value)) { throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"TripleDES"); } KeyValue = (byte[]) value.Clone(); KeySizeValue = value.Length * 8; } } // // public methods // new static public TripleDES Create() { return Create("System.Security.Cryptography.TripleDES"); } new static public TripleDES Create(String str) { return (TripleDES) CryptoConfig.CreateFromName(str); } public static bool IsWeakKey(byte[] rgbKey) { // All we have to check for here is (a) we're in 3-key mode (192 bits), and // (b) either K1 == K2 or K2 == K3 if (!IsLegalKeySize(rgbKey)) { throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize")); } byte[] rgbOddParityKey = Utils.FixupKeyParity(rgbKey); if (EqualBytes(rgbOddParityKey,0,8,8)) return(true); if ((rgbOddParityKey.Length == 24) && EqualBytes(rgbOddParityKey,8,16,8)) return(true); return(false); } // // private methods // private static bool EqualBytes(byte[] rgbKey, int start1, int start2, int count) { if (start1 < 0) throw new ArgumentOutOfRangeException("start1", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); if (start2 < 0) throw new ArgumentOutOfRangeException("start2", Environment.GetResourceString("ArgumentOutOfRange_NeedNonNegNum")); if ((start1+count) > rgbKey.Length) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue")); if ((start2+count) > rgbKey.Length) throw new ArgumentException(Environment.GetResourceString("Argument_InvalidValue")); for (int i = 0; i < count; i++) { if (rgbKey[start1+i] != rgbKey[start2+i]) return(false); } return(true); } private static bool IsLegalKeySize(byte[] rgbKey) { if (rgbKey != null && ((rgbKey.Length == 16) || (rgbKey.Length == 24))) return(true); return(false); } } }
Link Menu
This book is available now!
Buy at Amazon US or
Buy at Amazon UK
- XmlHierarchyData.cs
- LinqDataSourceUpdateEventArgs.cs
- ObjectCloneHelper.cs
- MenuItemCollectionEditor.cs
- StrokeRenderer.cs
- TabControlDesigner.cs
- ColorTranslator.cs
- SqlTypesSchemaImporter.cs
- Triangle.cs
- LoadedEvent.cs
- Tag.cs
- Route.cs
- OutputCacheProfile.cs
- Msec.cs
- DbgCompiler.cs
- SessionStateContainer.cs
- AvTraceDetails.cs
- SpecularMaterial.cs
- Renderer.cs
- Focus.cs
- Label.cs
- X509Certificate.cs
- SecurityResources.cs
- MULTI_QI.cs
- ObjectListFieldCollection.cs
- SecurityPermission.cs
- DecoderExceptionFallback.cs
- XmlArrayAttribute.cs
- CatchBlock.cs
- GiveFeedbackEvent.cs
- HierarchicalDataBoundControlAdapter.cs
- ProxyWebPart.cs
- WebPartMovingEventArgs.cs
- Hex.cs
- TreeBuilderXamlTranslator.cs
- HiddenFieldPageStatePersister.cs
- BitArray.cs
- WindowsGrip.cs
- BaseParser.cs
- GatewayIPAddressInformationCollection.cs
- LifetimeServices.cs
- FontDialog.cs
- ProcessModule.cs
- TextRangeEditLists.cs
- BitmapEffectInputConnector.cs
- ZoneButton.cs
- DrawingContextWalker.cs
- IncrementalReadDecoders.cs
- StrongNameIdentityPermission.cs
- DialogResultConverter.cs
- PackageFilter.cs
- TimestampInformation.cs
- ContentAlignmentEditor.cs
- SingleQueryOperator.cs
- WindowsAuthenticationModule.cs
- OLEDB_Util.cs
- DecoderFallbackWithFailureFlag.cs
- RadioButtonBaseAdapter.cs
- LayoutEvent.cs
- XmlObjectSerializerWriteContextComplex.cs
- MainMenu.cs
- RotateTransform.cs
- CodeGeneratorOptions.cs
- columnmapfactory.cs
- PropertyValueUIItem.cs
- ErrorCodes.cs
- HMACSHA1.cs
- Query.cs
- OutputCacheSection.cs
- EntityTransaction.cs
- DataGridViewCellEventArgs.cs
- SetMemberBinder.cs
- EntityDataSourceReferenceGroup.cs
- TCPListener.cs
- XamlFigureLengthSerializer.cs
- CellParagraph.cs
- OdbcConnectionHandle.cs
- Hex.cs
- ConnectionProviderAttribute.cs
- sqlnorm.cs
- Common.cs
- WebSysDisplayNameAttribute.cs
- LeftCellWrapper.cs
- WebUtil.cs
- XmlNodeList.cs
- WorkItem.cs
- NavigationService.cs
- TextRange.cs
- ListSortDescriptionCollection.cs
- TextServicesContext.cs
- InkCanvasAutomationPeer.cs
- XmlWrappingWriter.cs
- Exceptions.cs
- TemplateApplicationHelper.cs
- QueryPageSettingsEventArgs.cs
- BamlTreeUpdater.cs
- DbFunctionCommandTree.cs
- SortableBindingList.cs
- ControlEvent.cs
- EmptyEnumerator.cs