C#.NET Framework 使用BC库（BouncyCastle） RSA 公钥加密私钥解密 ver:20230706

环境说明：

.NET Framework 4.6 的控制台程序。

2020年以后，有部分PKCS8私钥（openssl生成）无法用RsaUtil.LoadPrivateKey(strPriPkcs8, "PKCS8")来解析（https://www.cnblogs.com/runliuv/p/17474269.html）

可以尝试用BC库来处理。

另外，在.NET中：私钥加密，公钥解密。也只能用BC库实现。

加密解析：

//假设私钥长度为1024， 1024/8-11=117。
//如果明文的长度小于117，直接全加密，然后转base64。(data.Length <= maxBlockSize)
//如果明文长度大于117，则每117分一段加密，写入到另一个Stream中，最后转base64。

解密解析：

//假设私钥长度为1024， 1024/8 =128。
//如果明文的长度小于 128，直接全解密。(data.Length <= maxBlockSize)
//如果明文长度大于 128，则每 128 分一段解密，写入到另一个Stream中，最后 GetString。

用“支付宝开放平台开发助手”生成一组公私钥：

PKCS8私钥：

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

与之匹配的 PKCS1 私钥，用助手转换的：

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

与之匹配的公钥：

MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDM9As4OkFLUyEmtqVJJaHkAf0xKR3aq38q6FqSi1vQfy1hUjhh/Z8k5NaT2WnmnchGUOoGsvwtKVAHrS62qvWzAPy7sauvG/O7hu1l+3SsrRDtv/O6hqRjEbPex/hpZM1opdkDtiiuHB5wHFYnD7JouWme9lNAViRcj4bXfqnZqwIDAQAB

BCSignUtil 辅助类，nuget 中引用 Portable.BouncyCastle。

using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Encodings;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Security;
using System;
using System.IO;
using System.Text;

namespace CommonUtils
{
    public static class BCSignUtil
    {
        /// 
        /// 签名
        /// 
        /// 原数据字符串
        /// 必须是PKCS8的
        /// 算法
        /// 
        public static string SignData(string orgData, string privateKeyPKCS8, string algorithm)
        {
            if (string.IsNullOrEmpty(orgData))
                throw new Exception("字符串不能为空!");

            if (string.IsNullOrEmpty(privateKeyPKCS8))
                throw new Exception("privateKeyPKCS8不能为空!");

            if (string.IsNullOrEmpty(privateKeyPKCS8))
                throw new Exception("algorithm 不能为空!");

            AsymmetricKeyParameter priKey = GetPrivateKeyParameter(privateKeyPKCS8);

            byte[] byteData = Encoding.UTF8.GetBytes(orgData);

            ISigner normalSig = SignerUtilities.GetSigner(algorithm);
            normalSig.Init(true, priKey);
            normalSig.BlockUpdate(byteData, 0, byteData.Length);//注意：是byte数组和数组长度，别写成string的长度了
            byte[] normalResult = normalSig.GenerateSignature(); //签名结果
            string sign = Convert.ToBase64String(normalResult);

            return sign;
        }

        private static AsymmetricKeyParameter GetPrivateKeyParameter(string privateKeyPem)
        {
            //获取私钥纯字符串
            privateKeyPem = privateKeyPem.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();
            privateKeyPem = privateKeyPem.Replace("-----BEGIN PRIVATE KEY-----", "").Replace("-----END PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

            byte[] privateInfoByte = Convert.FromBase64String(privateKeyPem);

            AsymmetricKeyParameter priKey = PrivateKeyFactory.CreateKey(privateInfoByte);
            return priKey;
        }

        /// 
        /// 验证签名
        /// 
        /// 原数据字符串
        /// 公钥
        /// 对方的签名串
        /// 算法
        /// 
        public static bool VerifySignature(string orgData, string publicKeyPem, string responseSign, string algorithm)
        {

            AsymmetricKeyParameter pubKey = GetPublicKeyParameter(publicKeyPem);


            byte[] signBytes = Convert.FromBase64String(responseSign);
            byte[] plainBytes = Encoding.UTF8.GetBytes(orgData);

            ISigner verifier = SignerUtilities.GetSigner(algorithm);
            verifier.Init(false, pubKey);
            verifier.BlockUpdate(plainBytes, 0, plainBytes.Length);//注意：是byte数组和数组长度，别写成string的长度了

            bool isOK = verifier.VerifySignature(signBytes); //验签结果
            return isOK;
        }

        private static AsymmetricKeyParameter GetPublicKeyParameter(string publicKeyPem)
        {
            //获取公钥纯字符串
            publicKeyPem = publicKeyPem.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

            byte[] publicInfoByte = Convert.FromBase64String(publicKeyPem);

            AsymmetricKeyParameter pubKey = PublicKeyFactory.CreateKey(publicInfoByte);
            return pubKey;
        }

        /// 
        /// RSA加密
        /// 
        /// 数据
        /// 私钥、公钥
        /// 是否为公钥
        /// 私钥长度，一般是1024或2048
        /// 
        public static string EncryptByKey(string orgData, string key, bool isPublicKey, int privateKeySize)
        {
            //非对称加密算法，加解密用  
            IAsymmetricBlockCipher engine = new Pkcs1Encoding(new RsaEngine());
            //加密  

            //1024长度是117，双方协商好
            int maxBlockSize = privateKeySize / 8 - 11; //加密块最大长度限制

            engine.Init(true, isPublicKey ? GetPublicKeyParameter(key) : GetPrivateKeyParameter(key));
            byte[] byteData = System.Text.Encoding.UTF8.GetBytes(orgData);

            int inputLen = byteData.Length;
            MemoryStream ms = new MemoryStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offSet > 0)
            {
                if (inputLen - offSet > maxBlockSize)
                {
                    cache = engine.ProcessBlock(byteData, offSet, maxBlockSize);
                }
                else
                {
                    cache = engine.ProcessBlock(byteData, offSet, inputLen - offSet);
                }
                ms.Write(cache, 0, cache.Length);
                i++;
                offSet = i * maxBlockSize;
            }
            byte[] encryptedData = ms.ToArray();

            //var ResultData = engine.ProcessBlock(byteData, 0, byteData.Length);
            return Convert.ToBase64String(encryptedData);
            //Console.WriteLine("密文（base64编码）:" + Convert.ToBase64String(testData) + Environment.NewLine);

        }
        /// 
        /// RSA解密
        /// 
        /// 数据
        /// 私钥、公钥
        /// 是否为公钥
        /// 私钥长度，一般是1024或2048
        /// 
        public static string DecryptByKey(string orgData, string key, bool isPublicKey, int privateKeySize)
        {
            orgData = orgData.Replace("\r", "").Replace("\n", "").Replace(" ", "");
            //非对称加密算法，加解密用  
            IAsymmetricBlockCipher engine = new Pkcs1Encoding(new RsaEngine());


            //解密  


            //1024长度是128，双方协商好
            int maxBlockSize = privateKeySize / 8; //解密块最大长度限制

            engine.Init(false, isPublicKey ? GetPublicKeyParameter(key) : GetPrivateKeyParameter(key));
            byte[] byteData = Convert.FromBase64String(orgData);

            int inputLen = byteData.Length;
            MemoryStream ms = new MemoryStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offSet > 0)
            {
                if (inputLen - offSet > maxBlockSize)
                {
                    cache = engine.ProcessBlock(byteData, offSet, maxBlockSize);
                }
                else
                {
                    cache = engine.ProcessBlock(byteData, offSet, inputLen - offSet);
                }
                ms.Write(cache, 0, cache.Length);
                i++;
                offSet = i * maxBlockSize;
            }
            byte[] encryptedData = ms.ToArray();

            //var ResultData = engine.ProcessBlock(byteData, 0, byteData.Length);
            return Encoding.UTF8.GetString(ms.ToArray());
            //Console.WriteLine("密文（base64编码）:" + Convert.ToBase64String(testData) + Environment.NewLine);

        }

    }
}

使用代码：

using CommonUtils;
using System;

namespace ConsoleNetFxRsa加密签名使用BC库
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                //PKCS8格式私钥
                string strPriPkcs8 = "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";
                //PKCS1格式私钥
                string strPriPkcs1 = "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";
                //公钥
                string strPub = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDM9As4OkFLUyEmtqVJJaHkAf0xKR3aq38q6FqSi1vQfy1hUjhh/Z8k5NaT2WnmnchGUOoGsvwtKVAHrS62qvWzAPy7sauvG/O7hu1l+3SsrRDtv/O6hqRjEbPex/hpZM1opdkDtiiuHB5wHFYnD7JouWme9lNAViRcj4bXfqnZqwIDAQAB";

                string strDJM = "泰酷拉！123ABC";//待签名字符串
                strDJM = "泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC泰酷拉！123ABC";//待加密字符串，超过117字符的测试

                Console.WriteLine("待签名字符串：" + strDJM);                

                #region 一、私钥签名
                //string algorithm = "SHA1withRSA";
                string algorithm = "SHA256withRSA";
                string strSigned = BCSignUtil.SignData(strDJM, strPriPkcs8, algorithm); //PKCS8
                Console.WriteLine("签名值：" + strSigned);
                #endregion

                #region 二、公钥验签（验证签名）
                //二、公钥验签（验证签名）
                //验证签名
                bool bCheck = BCSignUtil.VerifySignature(strDJM, strPub, strSigned, algorithm);//验证签名双方要保持一致
                Console.WriteLine("验证签名：" + bCheck.ToString());
                #endregion

　　　　　　　　　　//私钥长度，常用 1024 或 2048
                int privateKeySize = 1024;

                //公钥加密
               string strJiamihou=  BCSignUtil.EncryptByKey(strDJM, strPub,true, privateKeySize);
                Console.WriteLine("加密后：" + strJiamihou);

                //私钥解密
                string strJiemihou = BCSignUtil.DecryptByKey(strJiamihou, strPriPkcs8, false, privateKeySize);
                Console.WriteLine("解密后：" + strJiemihou);

                //私钥加密
                strJiamihou = BCSignUtil.EncryptByKey(strDJM, strPriPkcs8, false, privateKeySize);
                Console.WriteLine("私钥加密后：" + strJiamihou);

                //公钥解密
                strJiemihou = BCSignUtil.DecryptByKey(strJiamihou, strPub, true, privateKeySize);
                Console.WriteLine("公钥解密后：" + strJiemihou);
            }
            catch (Exception ex)
            {
                Console.WriteLine("ex:" + ex.Message);
            }

            Console.WriteLine("hello END.");
            Console.ReadKey();
        }
    }
}

这里演示了2组：

1：公钥加密，私钥解密。

2：私钥加密，公钥解密。

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原文地址：https://www.cnblogs.com/runliuv/p/17531440.html

C#.NET Framework 使用BC库（BouncyCastle） RSA 公钥加密 私钥解密 ver:20230706

C#.NET Framework 使用BC库（BouncyCastle） RSA 公钥加密私钥解密 ver:20230706