C#.NET Framework RSA 私鑰簽名公鑰驗籤（驗證簽名） ver:20230612

環境說明：

.NET Framework 4.6 的控制檯程式。

.NET Framework 對於RSA的支援：NET Framework 內建只支援XML格式的私鑰/公鑰。如果要用PKCS1,PKCS8格式的，要用到三方庫BouncyCastle。

核心重點是拿到 .NET 的RSACryptoServiceProvider 物件。

簽名（雙方要協商好編碼）：

1.將原始報文用UTF8轉為byte陣列。(引數為byte[] buffer) 原始報文的編碼雙方要協商好。

2.呼叫SignData(byte[] buffer, object halg)方法，其中halg 是HASH演演算法，雙方要協商好，有：SHA256、SHA1、MD5。SHA256對應JAVA的 SHA256withRSA. (其它還有 SHA1withRSA，MD5withRSA)

3.將輸出結果轉為BASE64字串。輸出結果轉字串的編碼，雙方要協商好，不一定用BASE64。

公鑰驗籤：

1.將原始報文用UTF8轉為byte陣列。(引數為byte[] buffer)

2.將簽名串（BASE64字串）用Convert.FromBase64String（）轉為byte陣列。（引數為：byte[] signature）

3.使用 VerifyData(byte[] buffer, object halg, byte[] signature); 方法驗籤。其中halg 是HASH演演算法，有：SHA256、SHA1、MD5。

用「支付寶開放平臺開發助手」生成一組公私鑰：

PKCS8私鑰：

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==

與之匹配的 PKCS1 私鑰，用助手轉換的：

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

與之匹配的公鑰：

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

nuget 中參照 Portable.BouncyCastle。

工具類：

RsaUtil 的作用：將私鑰（PKCS1,PKCS8）、公鑰、私鑰證書、公鑰證書轉為.NET RSACryptoServiceProvider 物件。

using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Security;
using System;
using System.IO;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;

namespace CommonUtils
{
    /// <summary>
    /// 將私鑰（PKCS1,PKCS8）、公鑰、私鑰證書、公鑰證書轉為.NET RSACryptoServiceProvider 物件
    /// </summary>
    public static class RsaUtil
    {
        #region 載入私鑰


        /// <summary>
        /// 轉換私鑰字串為RSACryptoServiceProvider
        /// </summary>
        /// <param name="privateKeyStr">私鑰字串</param>
        /// <param name="keyFormat">PKCS8,PKCS1</param>
        /// <param name="signType">RSA 私鑰長度1024 ,RSA2 私鑰長度2048</param>
        /// <returns></returns>
        public static RSACryptoServiceProvider LoadPrivateKey(string privateKeyStr, string keyFormat)
        {
            string signType = "RSA";
            if (privateKeyStr.Length > 1024)
            {
                signType = "RSA2";
            }
            //PKCS8,PKCS1
            if (keyFormat == "PKCS1")
            {
                return LoadPrivateKeyPKCS1(privateKeyStr, signType);
            }
            else
            {
                return LoadPrivateKeyPKCS8(privateKeyStr);
            }
        }

        /// <summary>
        /// PKCS1 格式私鑰轉 RSACryptoServiceProvider 物件
        /// </summary>
        /// <param name="strKey">pcsk1 私鑰的文字內容</param>
        /// <param name="signType">RSA 私鑰長度1024 ,RSA2 私鑰長度2048 </param>
        /// <returns></returns>
        public static RSACryptoServiceProvider LoadPrivateKeyPKCS1(string privateKeyPemPkcs1, string signType)
        {
            try
            {
                privateKeyPemPkcs1 = privateKeyPemPkcs1.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();
                privateKeyPemPkcs1 = privateKeyPemPkcs1.Replace("-----BEGIN PRIVATE KEY-----", "").Replace("-----END PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

                byte[] data = null;
                //讀取帶

                data = Convert.FromBase64String(privateKeyPemPkcs1);


                RSACryptoServiceProvider rsa = DecodeRSAPrivateKey(data, signType);
                return rsa;
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return null;
        }

        private static RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey, string signType)
        {
            byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;

            // --------- Set up stream to decode the asn.1 encoded RSA private key ------
            MemoryStream mem = new MemoryStream(privkey);
            BinaryReader binr = new BinaryReader(mem);  //wrap Memory Stream with BinaryReader for easy reading
            byte bt = 0;
            ushort twobytes = 0;
            int elems = 0;
            try
            {
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)
                    binr.ReadByte();    //advance 1 byte
                else if (twobytes == 0x8230)
                    binr.ReadInt16();    //advance 2 bytes
                else
                    return null;

                twobytes = binr.ReadUInt16();
                if (twobytes != 0x0102) //version number
                    return null;
                bt = binr.ReadByte();
                if (bt != 0x00)
                    return null;


                //------ all private key components are Integer sequences ----
                elems = GetIntegerSize(binr);
                MODULUS = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                E = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                D = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                P = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                Q = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DP = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DQ = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                IQ = binr.ReadBytes(elems);


                // ------- create RSACryptoServiceProvider instance and initialize with public key -----
                CspParameters CspParameters = new CspParameters();
                CspParameters.Flags = CspProviderFlags.UseMachineKeyStore;

                int bitLen = 1024;
                if ("RSA2".Equals(signType))
                {
                    bitLen = 2048;
                }

                RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(bitLen, CspParameters);
                //RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();

                RSAParameters RSAparams = new RSAParameters();
                RSAparams.Modulus = MODULUS;
                RSAparams.Exponent = E;
                RSAparams.D = D;
                RSAparams.P = P;
                RSAparams.Q = Q;
                RSAparams.DP = DP;
                RSAparams.DQ = DQ;
                RSAparams.InverseQ = IQ;
                RSA.ImportParameters(RSAparams);
                return RSA;
            }
            catch (Exception ex)
            {
                throw ex;
                // return null;
            }
            finally
            {
                binr.Close();
            }
        }

        private static int GetIntegerSize(BinaryReader binr)
        {
            byte bt = 0;
            byte lowbyte = 0x00;
            byte highbyte = 0x00;
            int count = 0;
            bt = binr.ReadByte();
            if (bt != 0x02)        //expect integer
                return 0;
            bt = binr.ReadByte();

            if (bt == 0x81)
                count = binr.ReadByte();    // data size in next byte
            else
                if (bt == 0x82)
            {
                highbyte = binr.ReadByte(); // data size in next 2 bytes
                lowbyte = binr.ReadByte();
                byte[] modint = { lowbyte, highbyte, 0x00, 0x00 };
                count = BitConverter.ToInt32(modint, 0);
            }
            else
            {
                count = bt;     // we already have the data size
            }

            while (binr.ReadByte() == 0x00)
            {    //remove high order zeros in data
                count -= 1;
            }
            binr.BaseStream.Seek(-1, SeekOrigin.Current);        //last ReadByte wasn't a removed zero, so back up a byte
            return count;
        }

        /// <summary>
        /// PKCS8 文字轉RSACryptoServiceProvider 物件
        /// </summary>
        /// <param name="privateKeyPemPkcs8"></param>
        /// <returns></returns>
        public static RSACryptoServiceProvider LoadPrivateKeyPKCS8(string privateKeyPemPkcs8)
        {

            try
            {
                //PKCS8是「BEGIN PRIVATE KEY」
                privateKeyPemPkcs8 = privateKeyPemPkcs8.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();
                privateKeyPemPkcs8 = privateKeyPemPkcs8.Replace("-----BEGIN PRIVATE KEY-----", "").Replace("-----END PRIVATE KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

                //pkcs8 文字先轉為 .NET XML 私鑰字串
                string privateKeyXml = RSAPrivateKeyJava2DotNet(privateKeyPemPkcs8);

                RSACryptoServiceProvider publicRsa = new RSACryptoServiceProvider();
                publicRsa.FromXmlString(privateKeyXml);
                return publicRsa;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// PKCS8 私鑰文字 轉 .NET XML 私鑰文字
        /// </summary>
        /// <param name="privateKeyPemPkcs8"></param>
        /// <returns></returns>
        public static string RSAPrivateKeyJava2DotNet(string privateKeyPemPkcs8)
        {
            RsaPrivateCrtKeyParameters privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(Convert.FromBase64String(privateKeyPemPkcs8));
            return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent><P>{2}</P><Q>{3}</Q><DP>{4}</DP><DQ>{5}</DQ><InverseQ>{6}</InverseQ><D>{7}</D></RSAKeyValue>",
            Convert.ToBase64String(privateKeyParam.Modulus.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.PublicExponent.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.P.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.Q.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.DP.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.DQ.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.QInv.ToByteArrayUnsigned()),
            Convert.ToBase64String(privateKeyParam.Exponent.ToByteArrayUnsigned()));
        }

        #endregion


        /// <summary>
        /// 載入公鑰證書
        /// </summary>
        /// <param name="publicKeyCert">公鑰證書文字內容</param>
        /// <returns></returns>
        public static RSACryptoServiceProvider LoadPublicCert(string publicKeyCert)
        {

            publicKeyCert = publicKeyCert.Replace("-----BEGIN CERTIFICATE-----", "").Replace("-----END CERTIFICATE-----", "").Replace("\r", "").Replace("\n", "").Trim();

            byte[] bytesCerContent = Convert.FromBase64String(publicKeyCert);
            X509Certificate2 x509 = new X509Certificate2(bytesCerContent);
            RSACryptoServiceProvider rsaPub = (RSACryptoServiceProvider)x509.PublicKey.Key;
            return rsaPub;

        }

        /// <summary>
        /// pem 公鑰文字 轉  .NET RSACryptoServiceProvider。
        /// </summary>
        /// <param name="publicKeyPem"></param>
        /// <returns></returns>
        public static RSACryptoServiceProvider LoadPublicKey(string publicKeyPem)
        {

            publicKeyPem = publicKeyPem.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("\r", "").Replace("\n", "").Trim();

            //pem 公鑰文字 轉  .NET XML 公鑰文字。
            string publicKeyXml = RSAPublicKeyJava2DotNet(publicKeyPem);

            RSACryptoServiceProvider publicRsa = new RSACryptoServiceProvider();
            publicRsa.FromXmlString(publicKeyXml);
            return publicRsa;


        }

        /// <summary>
        /// pem 公鑰文字 轉  .NET XML 公鑰文字。
        /// </summary>
        /// <param name="publicKey"></param>
        /// <returns></returns>
        private static string RSAPublicKeyJava2DotNet(string publicKey)
        {
            RsaKeyParameters publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(Convert.FromBase64String(publicKey));
            return string.Format("<RSAKeyValue><Modulus>{0}</Modulus><Exponent>{1}</Exponent></RSAKeyValue>",
                Convert.ToBase64String(publicKeyParam.Modulus.ToByteArrayUnsigned()),
                Convert.ToBase64String(publicKeyParam.Exponent.ToByteArrayUnsigned()));
        }


    }
}

呼叫範例：

using CommonUtils;
using System;
using System.Text;

namespace ConsoleNetFxRsaSign
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                //PKCS8格式私鑰
                string strPriPkcs8 = "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";
                //PKCS1格式私鑰
                string strPriPkcs1 = "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";
                //公鑰
                string strPub = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDM9As4OkFLUyEmtqVJJaHkAf0xKR3aq38q6FqSi1vQfy1hUjhh/Z8k5NaT2WnmnchGUOoGsvwtKVAHrS62qvWzAPy7sauvG/O7hu1l+3SsrRDtv/O6hqRjEbPex/hpZM1opdkDtiiuHB5wHFYnD7JouWme9lNAViRcj4bXfqnZqwIDAQAB";

                string strDJM = "泰酷拉！123ABC";//待簽名字串
                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";//待加密字串，超過117字元的測試

                Console.WriteLine("待簽名字串：" + strDJM);
                 
                //一、私鑰簽名
                //獲取私鑰物件
                var rsaPri = RsaUtil.LoadPrivateKey(strPriPkcs1, "PKCS1");
                //待簽名字串 轉為byte 陣列
                byte[] byToSign = Encoding.UTF8.GetBytes(strDJM); // 編碼要和其它語言一致，一般是：UTF8 
                byte[] bySigned = rsaPri.SignData(byToSign, "SHA256");//SHA256，對應JAVA，SHA256withRSA,簽名結果是 byte 陣列
                string strSigned = Convert.ToBase64String(bySigned);//將byte 陣列轉為字串，方便傳輸，一般是base64字串，其它型別需和對方協商
                Console.WriteLine("簽名值：" + strSigned);

                //二、公鑰驗籤（驗證簽名）
                //獲取公鑰物件
                var rsaPub = RsaUtil.LoadPublicKey(strPub);
                //將對方的簽名值轉為BYTE陣列。
                byte[] byToCheckSign = Convert.FromBase64String(strSigned);
                //將原始報文轉為byte陣列
                byte[] byBody = Encoding.UTF8.GetBytes(strDJM);// 編碼要和其它語言一致，一般是：UTF8 
                //驗證簽名
                bool bCheck = rsaPub.VerifyData(byBody,"SHA256", byToCheckSign);//驗證簽名雙方要保持一致
                Console.WriteLine("驗證簽名：" + bCheck.ToString());

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

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

C#.NET Framework RSA 私鑰簽名 公鑰驗籤（驗證簽名） ver:20230612

C#.NET Framework RSA 私鑰簽名公鑰驗籤（驗證簽名） ver:20230612