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

阅读原文时间：2023年07月10日阅读：1

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。

如果要和其它语言互通，这个分段长度需要和其它语言约定好，不一是私钥长度/8-11。

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;  
    }

    /// <summary>  
    /// 验证签名  
    /// </summary>  
    /// <param name="orgData">原数据字符串</param>  
    /// <param name="publicKeyPem">公钥</param>  
    /// <param name="responseSign">对方的签名串</param>  
    /// <param name="algorithm">算法</param>  
    /// <returns></returns>  
    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;  
    }

    /// <summary>  
    /// RSA加密  
    /// </summary>  
    /// <param name="orgData">数据</param>  
    /// <param name="key">私钥、公钥</param>  
    /// <param name="isPublicKey">是否为公钥</param>  
    /// <param name="privateKeySize">私钥长度，一般是1024或2048</param>  
    /// <returns></returns>  
    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);

    }  
    /// <summary>  
    /// RSA解密  
    /// </summary>  
    /// <param name="orgData">数据</param>  
    /// <param name="key">私钥、公钥</param>  
    /// <param name="isPublicKey">是否为公钥</param>  
    /// <param name="privateKeySize">私钥长度，一般是1024或2048</param>  
    /// <returns></returns>  
    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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