TripleDESCryptoServiceProvider.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Security / Cryptography / TripleDESCryptoServiceProvider.cs / 1305376 / TripleDESCryptoServiceProvider.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// [....]
// 
 
//
// TripleDESCryptoServiceProvider.cs 
//

namespace System.Security.Cryptography {
    [System.Runtime.InteropServices.ComVisible(true)] 
    public sealed class TripleDESCryptoServiceProvider : TripleDES {
        // 
        // public constructors 
        //
 
        [System.Security.SecuritySafeCritical]  // auto-generated
        public TripleDESCryptoServiceProvider () {
            if (!Utils.HasAlgorithm(Constants.CALG_3DES, 0))
                throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_AlgorithmNotAvailable")); 
            // Since the CSP only supports a CFB feedback of 8, make that the default
            FeedbackSizeValue = 8; 
        } 

        // 
        // public methods
        //

        [System.Security.SecuritySafeCritical]  // auto-generated 
        public override ICryptoTransform CreateEncryptor (byte[] rgbKey, byte[] rgbIV) {
            if (IsWeakKey(rgbKey)) 
                throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"TripleDES"); 
            return _NewEncryptor(rgbKey, ModeValue, rgbIV, FeedbackSizeValue, CryptoAPITransformMode.Encrypt);
        } 

        [System.Security.SecuritySafeCritical]  // auto-generated
        public override ICryptoTransform CreateDecryptor (byte[] rgbKey, byte[] rgbIV) {
            if (IsWeakKey(rgbKey)) 
                throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKey_Weak"),"TripleDES");
            return _NewEncryptor(rgbKey, ModeValue, rgbIV, FeedbackSizeValue, CryptoAPITransformMode.Decrypt); 
        } 

        public override void GenerateKey () { 
            KeyValue = new byte[KeySizeValue/8];
            Utils.StaticRandomNumberGenerator.GetBytes(KeyValue);
            // Never hand back a weak or semi-weak key
            while (TripleDES.IsWeakKey(KeyValue)) { 
                Utils.StaticRandomNumberGenerator.GetBytes(KeyValue);
            } 
        } 

        public override void GenerateIV () { 
            // IV is always 8 bytes/64 bits because block size is always 64 bits
            IVValue = new byte[8];
            Utils.StaticRandomNumberGenerator.GetBytes(IVValue);
        } 

        // 
        // private methods 
        //
 
        [System.Security.SecurityCritical]  // auto-generated
        private ICryptoTransform _NewEncryptor (byte[] rgbKey, CipherMode mode, byte[] rgbIV, int feedbackSize, CryptoAPITransformMode encryptMode) {
            int cArgs = 0;
            int[] rgArgIds = new int[10]; 
            Object[] rgArgValues = new Object[10];
            int algid = Constants.CALG_3DES; 
 
            // Check for bad values
            // 1) we don't support OFB mode in TripleDESCryptoServiceProvider 
            if (mode == CipherMode.OFB)
                throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_OFBNotSupported"));
            // 2) we only support CFB with a feedback size of 8 bits
            if ((mode == CipherMode.CFB) && (feedbackSize != 8)) 
                throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_CFBSizeNotSupported"));
 
            // Build the key if one does not already exist 
            if (rgbKey == null) {
                rgbKey = new byte[KeySizeValue/8]; 
                Utils.StaticRandomNumberGenerator.GetBytes(rgbKey);
            }

            // Set the mode for the encryptor (defaults to CBC) 
            if (mode != CipherMode.CBC) {
                rgArgIds[cArgs] = Constants.KP_MODE; 
                rgArgValues[cArgs] = mode; 
                cArgs += 1;
            } 

            // If not ECB mode -- pass in an IV
            if (mode != CipherMode.ECB) {
                if (rgbIV == null) { 
                    rgbIV = new byte[8];
                    Utils.StaticRandomNumberGenerator.GetBytes(rgbIV); 
                } 

                // 
                // We truncate IV's that are longer than the block size to 8 bytes : this is
                // done to maintain backward compatibility with the behavior shipped in V1.x.
                // The call to set the IV in CryptoAPI will ignore any bytes after the first 8
                // bytes. We'll still reject IV's that are shorter than the block size though. 
                //
                if (rgbIV.Length < 8) 
                    throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidIVSize")); 

                rgArgIds[cArgs] = Constants.KP_IV; 
                rgArgValues[cArgs] = rgbIV;
                cArgs += 1;
            }
 
            // If doing OFB or CFB, then we need to set the feed back loop size
            if ((mode == CipherMode.OFB) || (mode == CipherMode.CFB)) { 
                rgArgIds[cArgs] = Constants.KP_MODE_BITS; 
                rgArgValues[cArgs] = feedbackSize;
                cArgs += 1; 
            }

            // If the size of rgbKey is 16 bytes, then we're doing two-key 3DES, so switch algids
            // Note that we assume that if a CSP supports CALG_3DES then it also supports CALG_3DES_112 
            if (rgbKey.Length == 16) {
                algid = Constants.CALG_3DES_112; 
            } 

            // Create the encryptor object 
            return new CryptoAPITransform(algid, cArgs, rgArgIds,
                                          rgArgValues, rgbKey, PaddingValue,
                                          mode, BlockSizeValue, feedbackSize, false,
                                          encryptMode); 
        }
    } 
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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TripleDESCryptoServiceProvider.cs source code in C# .NET

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