EncryptionUtility.cs source code in C# .NET

                        Code:
                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / infocard / Service / managed / Microsoft / InfoCards / EncryptionUtility.cs / 1 / EncryptionUtility.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace Microsoft.InfoCards 
{
    using System; 
    using System.IdentityModel.Selectors; 
    using System.IdentityModel.Tokens;
    using System.ServiceModel.Security.Tokens; 
    using System.ServiceModel;
    using System.ServiceModel.Security;
    using System.IO;
    using System.Security.Cryptography.X509Certificates; 
    using System.Security.Cryptography.Xml;
    using System.Xml; 
    using System.Security.Principal; 
    using System.Security.Cryptography;
    using System.Text; 
    using System.Globalization;

    using IDT = Microsoft.InfoCards.Diagnostics.InfoCardTrace;
 
    //
    // Summary 
    //  This class provides utility function to enable encryption of tokens 
    //
    internal sealed class EncryptionUtility 
    {

        private EncryptionUtility()
        { 
        }
 
        // 
        // Summary
        //   Encrypt a security token 
        //
        // Parameters
        //  tokenToBeEncrypted - The security token that needs to be encrypted
        //  cert - The certificate of the party to which the token is to be encrypted 
        //  encryptingAlgorithm - The algorithm to use for encryption
        // 
        public static XmlElement EncryptSecurityToken( SecurityToken tokenToBeEncrypted, X509Certificate2 cert, 
            string encryptingAlgorithm, string asymmetricKeyWrapAlgorithm, ProtocolProfile profile )
        { 

            //
            // create the stream for data to be encrypted
            // 
            MemoryStream streamToBeEncrypted = new MemoryStream();
            XmlDictionaryWriter writer = XmlDictionaryWriter.CreateDictionaryWriter( new XmlTextWriter( new StreamWriter( streamToBeEncrypted ) ) ); 
            profile.TokenSerializer.WriteToken( writer, tokenToBeEncrypted ); 
            writer.Flush();
            streamToBeEncrypted.Seek( 0, SeekOrigin.Begin ); 

            return EncryptToken( streamToBeEncrypted, cert, encryptingAlgorithm, asymmetricKeyWrapAlgorithm, profile );
        }
 
        //
        // Summary 
        //   Encrypt a security token 
        //
        // Parameters 
        //  elem - The security token element that needs to be encrypted
        //  cert - The certificate of the party to which the token is to be encrypted
        //  encryptingAlgorithm - The algorithm to use for encryption
        //  keyWrapAlgorithm - Symmetric P ==> rasoaep. Asymmetric P ==> as specified 
        //
        public static XmlElement EncryptSecurityToken( XmlElement elem, X509Certificate2 cert, 
            string encryptingAlgorithm, string asymmetricKeyWrapAlgorithm, ProtocolProfile profile ) 
        {
 
            //
            // create the stream for data to be encrypted
            //
            MemoryStream streamToBeEncrypted = new MemoryStream(); 
            XmlDictionaryWriter writer = XmlDictionaryWriter.CreateDictionaryWriter( new XmlTextWriter( new StreamWriter( streamToBeEncrypted ) ) );
            elem.WriteTo( writer ); 
            writer.Flush(); 
            streamToBeEncrypted.Seek( 0, SeekOrigin.Begin );
 
            return EncryptToken( streamToBeEncrypted, cert, encryptingAlgorithm, asymmetricKeyWrapAlgorithm, profile );
        }

        // 
        // Summary
        //   Encrypt a security token 
        // 
        // Parameters
        //  streamToBeEncrypted - The security token stream that needs to be encrypted 
        //  cert - The certificate of the party to which the token is to be encrypted
        //  encryptingAlgorithm - The algorithm to use for encryption
        //  keyWrapAlgorithm - Symmetric P ==> rasoaep. Asymmetric P ==> as specified
        // 
        private static XmlElement EncryptToken( MemoryStream streamToBeEncrypted, X509Certificate2 cert,
            string encryptingAlgorithm, string asymmetricKeyWrapAlgorithm, ProtocolProfile profile ) 
        { 
            IDT.TraceDebug( "Encrypting the security token" );
            IDT.ThrowInvalidArgumentConditional( String.IsNullOrEmpty( encryptingAlgorithm ), "encryptingAlgorithm" ); 
            IDT.ThrowInvalidArgumentConditional( null == cert, "cert" );
            IDT.TraceDebug( "Encrypting issued token with {0} algorithm", encryptingAlgorithm );
            IDT.TraceDebug( "Encrypting issued token with {0} certificate", cert.FriendlyName );
 
            SecurityToken encryptingToken = new X509SecurityToken( cert, "id" );
 
            SecurityAlgorithmSuite suite = SecurityAlgorithmSuite.Default; 
            switch( encryptingAlgorithm )
            { 
                case SecurityAlgorithms.Aes128Encryption:
                    suite = SecurityAlgorithmSuite.Basic128;
                    break;
                case SecurityAlgorithms.Aes192Encryption: 
                    suite = SecurityAlgorithmSuite.Basic192;
                    break; 
                case SecurityAlgorithms.Aes256Encryption: 
                    suite = SecurityAlgorithmSuite.Basic256;
                    break; 
                case SecurityAlgorithms.TripleDesEncryption:
                    suite = SecurityAlgorithmSuite.TripleDes;
                    break;
                default: 
                    throw IDT.ThrowHelperError( new TokenCreationException(
                        SR.GetString( SR.UnsupportedEncryptionAlgorithm, encryptingAlgorithm ) ) ); 
            } 

 
            //
            // create the keys to be used for encryption
            //
            SecurityKeyIdentifier encryptingKeyIdentifier = new SecurityKeyIdentifier( encryptingToken.CreateKeyIdentifierClause() ); 

 
            int encryptedKeySize = suite.DefaultEncryptionKeyDerivationLength / 8; 

 
            byte[ ] keyToWrap = new byte[ encryptedKeySize ];
            RNGCryptoServiceProvider random = new RNGCryptoServiceProvider();
            random.GetNonZeroBytes( keyToWrap );
 
            WrappedKeySecurityToken wrappedKeyToken = new WrappedKeySecurityToken( string.Empty,
                keyToWrap, asymmetricKeyWrapAlgorithm, encryptingToken, encryptingKeyIdentifier ); 
 
            SecurityKeyIdentifier keyIdentifier = new SecurityKeyIdentifier( new EncryptedKeyIdentifierClause( wrappedKeyToken.GetWrappedKey(),
                wrappedKeyToken.WrappingAlgorithm, wrappedKeyToken.WrappingTokenReference ) ); 


            SymmetricSecurityKey encryptingCrypto = ( SymmetricSecurityKey )wrappedKeyToken.SecurityKeys[ 0 ];
 
            //
            // Use the algorithm provided and encrypt the data 
            // 
            SymmetricAlgorithm algorithm = encryptingCrypto.GetSymmetricAlgorithm( encryptingAlgorithm );
            EncryptedData encryptedData = new EncryptedData(); 
            encryptedData.TokenSerializer = profile.TokenSerializer;
            encryptedData.KeyIdentifier = keyIdentifier;
            encryptedData.EncryptionMethod = encryptingAlgorithm;
            encryptedData.Type = EncryptedXml.XmlEncElementUrl; 
            encryptedData.SetUpEncryption( algorithm, streamToBeEncrypted.GetBuffer(), 0, Convert.ToInt32( streamToBeEncrypted.Length ) );
 
            // 
            // write the encrypted data to a memory stream
            // 
            IDT.TraceDebug( "Writing encrypted token to memory stream" );
            MemoryStream encryptedStream = new MemoryStream();
            XmlDictionaryWriter writer = XmlDictionaryWriter.CreateDictionaryWriter( new XmlTextWriter( new StreamWriter( encryptedStream ) ) );
            encryptedData.WriteTo( writer ); 
            writer.Flush();
            encryptedStream.Seek( 0, SeekOrigin.Begin ); 
 
            //
            // Create an XmlElement for the encrypted data 
            //
            XmlDocument doc = new XmlDocument();
            XmlElement tokenXml = ( XmlElement )doc.ReadNode( Utility.CreateReaderWithQuotas( encryptedStream ) );
 
            Array.Clear(
                        streamToBeEncrypted.GetBuffer(), 
                        0, 
                        Convert.ToInt32( streamToBeEncrypted.Length ) );
            Array.Clear( 
                        encryptedStream.GetBuffer(),
                        0,
                        Convert.ToInt32( encryptedStream.Length ) );
            streamToBeEncrypted.Close(); 
            encryptedStream.Close();
            return tokenXml; 
        } 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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