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https://blog.csdn.net/woaimx_1314/article/details/131118360?share_token=9030224E-F6FB-4BC7-A162-946E9E3731F8&tt_from=weixin&utm_source=weixin&utm_medium=toutiao_ios&utm_campaign=client_share&wxshare_count=1

https://blog.csdn.net/qq_24078843/article/details/80776769?share_token=2BBE8FF4-8886-406A-9074-E2957B4DA4EB&tt_from=weixin&utm_source=weixin&utm_medium=toutiao_ios&utm_campaign=client_share&wxshare_count=1

环境说明：

.NET CORE 版本:.NET 6 。

.NET CORE 对于RSA的支持：

1. .NET 6 中内置了对 PKCS1,PKCS8 2种私钥格式的支持。

2. 如果你要部署在Linux,docker ,k8s 中；一定要用 “RSA”这个类，不能是 .NET FRAMEWORK 的 RSACryptoServiceProvider。

3. .NET 中默认加密算法为“RSA/ECB/PKCS1Padding” ，要和JAVA互通，JAVA 那边也得是 RSA/ECB/PKCS1Padding 。

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。while (blockSize > 0)

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。while (blockSize > 0)

用“支付宝开放平台开发助手”生成一组公私钥：

PKCS8私钥：

MIICeQIBADANBgkqhkiG9w0BAQEFAASCAmMwggJfAgEAAoGBAMz0Czg6QUtTISa2pUkloeQB/TEpHdqrfyroWpKLW9B/LWFSOGH9nyTk1pPZaeadyEZQ6gay/C0pUAetLraq9bMA/Luxq68b87uG7WX7dKytEO2/87qGpGMRs97H+GlkzWil2QO2KK4cHnAcVicPsmi5aZ72U0BWJFyPhtd+qdmrAgMBAAECgYEAvW67iAbgHt0BASVD9C3iSjpEaVHVlC165o/IVzaTcEx8Bz3Ve0zN8W3JnvIO3ebsG4HiLLr2Nk++9rltOc0eNeGMv7F1e/OFot1wN0ON6s1g4bYh1z5Uz8FcYiMWcqHHICrx+oSFeK9x+I2Zge7enQXcsVnqEhm77ZE5YczSryECQQD9nB58e5efYchF+cYbmURioX18cUMuhQbB9Aq2N55cd689Lg35KZqT8JQTp/8tQSdCJG8d2nU8VKspUKTEAuaDAkEAzuKIIoc9PVJvy90LhIPA9c1S8BPCI7EMCaTZqJ5o3VaR2dqvUZDGX7kL3kYkQ+n7mq3KIECvkEFzA+FOP96XuQJBAJQTKHW0T/YeSKoayUHp/lS8R6F2HCy4PRbXn71+wfbpZqcJEd2OHhQM3tiPOV258esbjMlYeSUNppZL4LgVnXMCQQC7Lvs9Ql+GPDAqo7ToEM1lmICR906QPIBHuX+1sJ3wpYMROWumwPa7ZRH36j6ls+6R5OwcgmpWeuE1gYTrBNsBAkEAn2pEtAljX1foQff6CLozYg/J6J9RmVFcJ6qz0LX3052qNFBQYw8CMHB7VkVNzsDIDC8LX5uP2pzTrdPLew+pPA==

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

加密工具类：

RsaEncryptUtil

using System.Security.Cryptography;
using System.Text;

namespace CommonUtils
{
    public static class RsaEncryptUtil
    {
        #region 标准的-公钥加密-私钥解密

        /** 默认编码字符集 */
        private static string DEFAULT_CHARSET = "UTF-8";

        /// <summary>
        /// 公钥加密（超过 私钥长度 / 8 - 11，分段加密）
        /// </summary>
        /// <param name="content">明文</param>
        /// <param name="charset">编码</param>
        /// <param name="publicKeyPem">公钥</param>
        /// <returns></returns>
        /// <exception cref="Exception"></exception>
        public static string RSAEncrypt(string content, string charset, string publicKeyPem)
        {
            try
            {
                //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。while (blockSize > 0)                 

                //转为纯字符串，不带格式
                publicKeyPem = publicKeyPem.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

                RSA rsa = RSA.Create();
                rsa.ImportSubjectPublicKeyInfo(Convert.FromBase64String(publicKeyPem), out _);

                if (string.IsNullOrEmpty(charset))
                {
                    charset = DEFAULT_CHARSET;
                }
                byte[] data = Encoding.GetEncoding(charset).GetBytes(content);
                int maxBlockSize = rsa.KeySize / 8 - 11; //加密块最大长度限制
                if (data.Length <= maxBlockSize)
                {
                    byte[] cipherbytes = rsa.Encrypt(data, RSAEncryptionPadding.Pkcs1);
                    return Convert.ToBase64String(cipherbytes);
                }
                MemoryStream plaiStream = new MemoryStream(data);
                MemoryStream crypStream = new MemoryStream();
                byte[] buffer = new byte[maxBlockSize];
                int blockSize = plaiStream.Read(buffer, 0, maxBlockSize);
                while (blockSize > 0)
                {
                    byte[] toEncrypt = new byte[blockSize];
                    Array.Copy(buffer, 0, toEncrypt, 0, blockSize);
                    byte[] cryptograph = rsa.Encrypt(toEncrypt, RSAEncryptionPadding.Pkcs1);
                    crypStream.Write(cryptograph, 0, cryptograph.Length);
                    blockSize = plaiStream.Read(buffer, 0, maxBlockSize);
                }

                return Convert.ToBase64String(crypStream.ToArray(), Base64FormattingOptions.None);
            }
            catch (Exception ex)
            {
                throw new Exception("EncryptContent = " + content + ",charset = " + charset, ex);
            }
        }

        /// <summary>
        /// 私钥解密（超过 私钥长度 / 8 - 11，分段加密）
        /// </summary>
        /// <param name="content">密文</param>
        /// <param name="charset">编码</param>
        /// <param name="privateKeyPem">私钥</param>
        /// <param name="keyFormat">私钥格式 PKCS1,PKCS8</param>
        /// <returns></returns>
        /// <exception cref="Exception"></exception>
        public static string RSADecrypt(string content, string charset, string privateKeyPem, string keyFormat)
        {
            try
            {
                //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。while (blockSize > 0)                                 

                //转为纯字符串，不带格式
                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();


                RSA rsaCsp = RSA.Create();
                if (keyFormat == "PKCS8")
                    rsaCsp.ImportPkcs8PrivateKey(Convert.FromBase64String(privateKeyPem), out _);
                else if (keyFormat == "PKCS1")
                    rsaCsp.ImportRSAPrivateKey(Convert.FromBase64String(privateKeyPem), out _);
                else
                    throw new Exception("只支持PKCS8，PKCS1");

                if (string.IsNullOrEmpty(charset))
                {
                    charset = DEFAULT_CHARSET;
                }
                byte[] data = Convert.FromBase64String(content);
                int maxBlockSize = rsaCsp.KeySize / 8; //解密块最大长度限制
                if (data.Length <= maxBlockSize)
                {
                    byte[] cipherbytes = rsaCsp.Decrypt(data, RSAEncryptionPadding.Pkcs1);
                    return Encoding.GetEncoding(charset).GetString(cipherbytes);
                }
                MemoryStream crypStream = new MemoryStream(data);
                MemoryStream plaiStream = new MemoryStream();
                byte[] buffer = new byte[maxBlockSize];
                int blockSize = crypStream.Read(buffer, 0, maxBlockSize);
                while (blockSize > 0)
                {
                    byte[] toDecrypt = new byte[blockSize];
                    Array.Copy(buffer, 0, toDecrypt, 0, blockSize);
                    byte[] cryptograph = rsaCsp.Decrypt(toDecrypt, RSAEncryptionPadding.Pkcs1);
                    plaiStream.Write(cryptograph, 0, cryptograph.Length);
                    blockSize = crypStream.Read(buffer, 0, maxBlockSize);
                }

                return Encoding.GetEncoding(charset).GetString(plaiStream.ToArray());
            }
            catch (Exception ex)
            {
                throw new Exception("DecryptContent = " + content + ",charset = " + charset, ex);
            }
        }

        #endregion

    }
}

调用代码：

// See https://aka.ms/new-console-template for more information

using CommonUtils;

try
{
    //PKCS8格式私钥
    string strPriPkcs8 = "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";
    //PKCS1格式私钥
    string strPriPkcs1 = "MIICXwIBAAKBgQDM9As4OkFLUyEmtqVJJaHkAf0xKR3aq38q6FqSi1vQfy1hUjhh/Z8k5NaT2WnmnchGUOoGsvwtKVAHrS62qvWzAPy7sauvG/O7hu1l+3SsrRDtv/O6hqRjEbPex/hpZM1opdkDtiiuHB5wHFYnD7JouWme9lNAViRcj4bXfqnZqwIDAQABAoGBAL1uu4gG4B7dAQElQ/Qt4ko6RGlR1ZQteuaPyFc2k3BMfAc91XtMzfFtyZ7yDt3m7BuB4iy69jZPvva5bTnNHjXhjL+xdXvzhaLdcDdDjerNYOG2Idc+VM/BXGIjFnKhxyAq8fqEhXivcfiNmYHu3p0F3LFZ6hIZu+2ROWHM0q8hAkEA/ZwefHuXn2HIRfnGG5lEYqF9fHFDLoUGwfQKtjeeXHevPS4N+Smak/CUE6f/LUEnQiRvHdp1PFSrKVCkxALmgwJBAM7iiCKHPT1Sb8vdC4SDwPXNUvATwiOxDAmk2aieaN1Wkdnar1GQxl+5C95GJEPp+5qtyiBAr5BBcwPhTj/el7kCQQCUEyh1tE/2HkiqGslB6f5UvEehdhwsuD0W15+9fsH26WanCRHdjh4UDN7YjzldufHrG4zJWHklDaaWS+C4FZ1zAkEAuy77PUJfhjwwKqO06BDNZZiAkfdOkDyAR7l/tbCd8KWDETlrpsD2u2UR9+o+pbPukeTsHIJqVnrhNYGE6wTbAQJBAJ9qRLQJY19X6EH3+gi6M2IPyeifUZlRXCeqs9C199OdqjRQUGMPAjBwe1ZFTc7AyAwvC1+bj9qc063Ty3sPqTw=";
    //公钥
    string strPub = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDM9As4OkFLUyEmtqVJJaHkAf0xKR3aq38q6FqSi1vQfy1hUjhh/Z8k5NaT2WnmnchGUOoGsvwtKVAHrS62qvWzAPy7sauvG/O7hu1l+3SsrRDtv/O6hqRjEbPex/hpZM1opdkDtiiuHB5wHFYnD7JouWme9lNAViRcj4bXfqnZqwIDAQAB";

    string strDJM = "泰酷拉！123ABC";//待加密字符串
    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("待加密字符串：" + strDJM);
    string charSet = "UTF-8";
    string strJMH = RsaEncryptUtil.RSAEncrypt(strDJM, charSet, strPub);//密文
    Console.WriteLine("密文：" + strJMH);

    string strDecryptedByPkcs8 = RsaEncryptUtil.RSADecrypt(strJMH, charSet, strPriPkcs8, "PKCS8");//使用PKCS8格式私钥解密
    Console.WriteLine("PKCS8 解密后：" + strDecryptedByPkcs8);

    string strDecryptedByPkcs1 = RsaEncryptUtil.RSADecrypt(strJMH, charSet, strPriPkcs1, "PKCS1");//使用PKCS1格式私钥解密

    Console.WriteLine("PKCS1 解密后：" + strDecryptedByPkcs1);

}
catch (Exception ex)
{

    Console.WriteLine("ex:" + ex.Message);
}

Console.WriteLine("Hello, World!");
Console.ReadKey();