RSAPKCS1KeyExchangeFormatter.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / clr / src / BCL / System / Security / Cryptography / RSAPKCS1KeyExchangeFormatter.cs / 1 / RSAPKCS1KeyExchangeFormatter.cs

                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 

namespace System.Security.Cryptography { 
    using System.Globalization; 

    [System.Runtime.InteropServices.ComVisible(true)] 
    public class RSAPKCS1KeyExchangeFormatter : AsymmetricKeyExchangeFormatter {
        RandomNumberGenerator RngValue;
        RSA _rsaKey;
 
        //
        // public constructors 
        // 

        public RSAPKCS1KeyExchangeFormatter() {} 

        public RSAPKCS1KeyExchangeFormatter(AsymmetricAlgorithm key) {
            if (key == null)
                throw new ArgumentNullException("key"); 
            _rsaKey = (RSA) key;
        } 
 
        //
        // public properties 
        //

        public override String Parameters {
            get { return ""; } 
        }
 
        public RandomNumberGenerator Rng { 
            get { return RngValue; }
            set { RngValue = value; } 
        }

        //
        // public methods 
        //
 
        public override void SetKey(AsymmetricAlgorithm key) { 
            if (key == null)
                throw new ArgumentNullException("key"); 
            _rsaKey = (RSA) key;
        }

        public override byte[] CreateKeyExchange(byte[] rgbData) { 
            if (_rsaKey == null)
                throw new CryptographicUnexpectedOperationException(Environment.GetResourceString("Cryptography_MissingKey")); 
 
            byte[] rgbKeyEx;
            if (_rsaKey is RSACryptoServiceProvider) { 
                rgbKeyEx = ((RSACryptoServiceProvider) _rsaKey).Encrypt(rgbData, false);
            }
            else {
                int cb = _rsaKey.KeySize/8; 
                if ((rgbData.Length + 11) > cb)
                    throw new CryptographicException(String.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Cryptography_Padding_EncDataTooBig"), cb-11)); 
                byte[]  rgbInput = new byte[cb]; 

                // 
                //  We want to pad to the following format:
                //      00 || 02 || PS || 00 || D
                //
                //      PS - pseudorandom non zero bytes 
                //      D - data
                // 
 
                if (RngValue == null) {
                    RngValue = RandomNumberGenerator.Create(); 
                }

                Rng.GetNonZeroBytes(rgbInput);
                rgbInput[0] = 0; 
                rgbInput[1] = 2;
                rgbInput[cb-rgbData.Length-1] = 0; 
                Buffer.InternalBlockCopy(rgbData, 0, rgbInput, cb-rgbData.Length, rgbData.Length); 

                // 
                //  Now encrypt the value and return it. (apply public key)
                //

                rgbKeyEx = _rsaKey.EncryptValue(rgbInput); 
            }
            return rgbKeyEx; 
        } 

        public override byte[] CreateKeyExchange(byte[] rgbData, Type symAlgType) { 
            return CreateKeyExchange(rgbData);
        }
    }
}
                        

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