关于RSA加密算法的长度问题

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Framework中提供的RSA算法规定，每次加密的字节数，不能超过密钥的长度值减去11,而每次加密得到的密文长度，却恰恰是密钥的长度。所以，如果要加密较长的数据，可以采用数据截取的方法，分段加密。或者增加自定义分块算法，进行加密。当然，你也可以加长密钥的长度，呵呵。下面是分段加解密代码片段，希望对程序媛们有帮助

public override byte[] Encrypt(byte[] sourceBytes)
        {
            CspParameters cspParams = new CspParameters();
            cspParams.KeyContainerName = KeyContainerName;
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(cspParams);

            int keySize = RSAalg.KeySize / 8;
            int bufferSize = keySize - 11;
            byte[] buffer = new  byte[bufferSize];
            MemoryStream msInput = new MemoryStream(sourceBytes);
            MemoryStream msOutput = new MemoryStream();
            int readLen = msInput.Read(buffer, 0, bufferSize); 
            while (readLen > 0)
            {

                byte[] dataToEnc = new byte[readLen];

                Array.Copy(buffer, 0, dataToEnc, 0, readLen);

                byte[] encData = RSAalg.Encrypt(dataToEnc, false);

                msOutput.Write(encData, 0, encData.Length);

                readLen = msInput.Read(buffer, 0, bufferSize);

            }

            msInput.Close();

            byte[] result = msOutput.ToArray();     //得到加密结果

            msOutput.Close();

            RSAalg.Clear();

            return result;

            //return RSAalg.Encrypt(sourceBytes, false);
        }

        public override byte[] Decrypt(byte[] cryptBytes)
        {
            CspParameters cspParams = new CspParameters();
            cspParams.KeyContainerName = KeyContainerName;
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider(cspParams);
            //return RSAalg.Decrypt(cryptBytes, false);
            int keySize = RSAalg.KeySize / 8;
            int bufferSize = keySize;// keySize - 11;
            byte[] buffer = new byte[bufferSize];
            MemoryStream msInput = new MemoryStream(cryptBytes);
            MemoryStream msOutput = new MemoryStream();
            int readLen = msInput.Read(buffer, 0, bufferSize);
            while (readLen > 0)
            {

                byte[] dataToDec = new byte[readLen];

                Array.Copy(buffer, 0, dataToDec, 0, readLen);

                byte[] decData = RSAalg.Decrypt(dataToDec, false);

                msOutput.Write(decData, 0, decData.Length);

                readLen = msInput.Read(buffer, 0, bufferSize);

            }

            msInput.Close();

            byte[] result = msOutput.ToArray();     //得到加密结果

            msOutput.Close();

            RSAalg.Clear();

            return result;
        }

关于RSA加密算法的长度问题

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原文地址：http://blog.csdn.net/nnsword/article/details/46439043