用RSA算法生成公钥私钥对，并加密解密文件内容

摘要：RSA算法生成公钥私钥对，发送方用RSA公钥加密，接收方用RSA私钥解密。文件内容签名和验证用DSA算法，用于验证文件内容没有被修改过。发送方除了发送加密后的密文，还要发送签名信息；接收方解密密文，还要验证接收的内容是否与原始发送的内容一致，即确保没有被篡改。

using System.Security.Cryptography;

private static readonly int CurrentBitStrength = 1024;

1. 生成公钥私钥对

        /// <summary>
        /// 生成公钥私钥对
        /// </summary>
        private void GenerateKeys()
        {
            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(CurrentBitStrength);
            string publicPrivateKeysContent = rsaProvider.ToXmlString(true);
            string publicOnlyKeysContent = rsaProvider.ToXmlString(false);
            ViewData["public-private"] = Session["public-private"] = publicPrivateKeysContent;
            ViewData["public-only"] = Session["public-only"] = publicOnlyKeysContent;


            DSACryptoServiceProvider dsaProvider = new DSACryptoServiceProvider();
            Session["dsa-public-private"] = dsaProvider.ToXmlString(true);
            Session["dsa-public-only"] = dsaProvider.ToXmlString(false);
        }

2. 加密

       /// <summary>
        /// 加密
        /// </summary>
        /// <param name="txtInput"></param>
        /// <returns></returns>
        private string EncryptContent(string txtInput)
        {
            int bitStrength = CurrentBitStrength;
            string publicOnlyKeys = Session["public-only"].ToString();
            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(bitStrength);
            byte[] plainBytes = System.Text.Encoding.UTF8.GetBytes(txtInput);
            //发送方RSA公钥加密
            rsaProvider.FromXmlString(publicOnlyKeys);
            byte[] cipherBytes = rsaProvider.Encrypt(plainBytes, false);


            //发送方DSA签名
            DSACryptoServiceProvider dsaProvider = new DSACryptoServiceProvider(CurrentBitStrength);
            dsaProvider.FromXmlString(Session["dsa-public-private"].ToString());
            byte[] signedBytes = dsaProvider.SignData(plainBytes);
            Session["DSA-Signed-Digest"] = signedBytes;
                        
            return Convert.ToBase64String(cipherBytes);
        }

3. 解密

       /// <summary>
        /// 解密
        /// </summary>
        /// <param name="txtEncryted"></param>
        /// <returns></returns>
        private string DecryptContent(string txtEncryted)
        {
            int bitStrength = CurrentBitStrength;
            string publicPrivateKeys = Session["public-Private"].ToString();
            RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider(bitStrength);
            rsaProvider.FromXmlString(publicPrivateKeys);


            //接收方RSA私钥解密
            byte[] encryptedBytes = Convert.FromBase64String(txtEncryted);
            byte[] plainBytes = rsaProvider.Decrypt(encryptedBytes, false);


            //接收方DSA验证签名
            byte[] signedBytes = (byte[])Session["DSA-Signed-Digest"];
            DSACryptoServiceProvider dsaProvider = new DSACryptoServiceProvider();
            dsaProvider.FromXmlString(Session["dsa-public-private"].ToString());
            bool isSigned = dsaProvider.VerifyData(plainBytes, signedBytes);


            return System.Text.Encoding.UTF8.GetString(plainBytes);
        }

备注：

此代码经过asp.net mvc调试环境验证，此处贴出核心部分代码，供参考。