RSA使用

今天在跟同事一起調試TCP通訊的時候，在RSA私鑰解密這塊，着實讓我費了一番心思。
流程大致是這樣的，終端登錄的時候使用固定的des密碼加密數據發送，平台接收后確認登錄信息后，會返回一個字符串，
該字符串是使用rsa公鑰加密的一個字符串，作為后續通訊時使用的des密碼。平台是使用JAVA開發的，該私鑰和公鑰文件會
在終端存一份。但是該文件是pem格式的，而且公鑰使用證書的方式，調試使用公鑰加密后的發送給平台，平台都是可以解密的。
但是平台發送回來的公鑰加密就是解密不正常。其中查找資料就不多說了，總算是解決了。這里做一個記錄，也做個分享。
其中使用到一個第三方庫：BouncyCastle,可以使用NuGet來安裝.
首先是RSA密鑰與Pem密鑰的互轉。

/// <summary>
        /// Pem密鑰轉RSA密鑰
        /// </summary>
        /// <param name="pemKey">Pem密鑰</param>
        /// <param name="isPrivateKey">是否是私鑰</param>
        /// <returns>RSA密鑰</returns>
        public static string PemToRSAKey(string pemKeyFileName, bool isPrivateKey)
        {
            string rsaKey = string.Empty;
            object pemObject = null;
            RSAParameters rsaPara = new RSAParameters();
            using (StreamReader sReader = new StreamReader(pemKeyFileName))
            {
                var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(sReader);
                pemObject = pemReader.ReadObject();

            }
            //RSA私鑰
            if (isPrivateKey)
            {
                RsaPrivateCrtKeyParameters key = (RsaPrivateCrtKeyParameters)pemObject;
                rsaPara = new RSAParameters
                {
                    Modulus = key.Modulus.ToByteArrayUnsigned(),
                    Exponent = key.PublicExponent.ToByteArrayUnsigned(),
                    D = key.Exponent.ToByteArrayUnsigned(),
                    P = key.P.ToByteArrayUnsigned(),
                    Q = key.Q.ToByteArrayUnsigned(),
                    DP = key.DP.ToByteArrayUnsigned(),
                    DQ = key.DQ.ToByteArrayUnsigned(),
                    InverseQ = key.QInv.ToByteArrayUnsigned(),
                };
            }
            //RSA公鑰
            else
            {
                RsaKeyParameters key = (RsaKeyParameters)pemObject;
                rsaPara = new RSAParameters
                {
                    Modulus = key.Modulus.ToByteArrayUnsigned(),
                    Exponent = key.Exponent.ToByteArrayUnsigned(),
                };
            }
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.ImportParameters(rsaPara);
            using (StringWriter sw = new StringWriter())
            {
                sw.Write(rsa.ToXmlString(isPrivateKey ? true : false));
                rsaKey = sw.ToString();
            }
            return rsaKey;
        }
        /// <summary>
        /// RSA密鑰轉Pem密鑰
        /// </summary>
        /// <param name="RSAKey">RSA密鑰</param>
        /// <param name="isPrivateKey">是否是私鑰</param>
        /// <returns>Pem密鑰</returns>
        public static string RSAKeyToPem(string RSAKey, bool isPrivateKey)
        {
            string pemKey = string.Empty;
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString(RSAKey);
            RSAParameters rsaPara = new RSAParameters();
            RsaKeyParameters key = null;
            //RSA私鑰
            if (isPrivateKey)
            {
                rsaPara = rsa.ExportParameters(true);
                key = new RsaPrivateCrtKeyParameters(
                    new BigInteger(1, rsaPara.Modulus), new BigInteger(1, rsaPara.Exponent), new BigInteger(1, rsaPara.D),
                    new BigInteger(1, rsaPara.P), new BigInteger(1, rsaPara.Q), new BigInteger(1, rsaPara.DP), new BigInteger(1, rsaPara.DQ),
                    new BigInteger(1, rsaPara.InverseQ));
            }
            //RSA公鑰
            else
            {
                rsaPara = rsa.ExportParameters(false);
                key = new RsaKeyParameters(false,
                    new BigInteger(1, rsaPara.Modulus),
                    new BigInteger(1, rsaPara.Exponent));
            }
            using (TextWriter sw = new StringWriter())
            {
                var pemWriter = new PemWriter(sw);
                pemWriter.WriteObject(key);
                pemWriter.Writer.Flush();
                pemKey = sw.ToString();
            }
            return pemKey;
        }

公鑰加密,以證書方式打開pem密鑰文件

 /// <summary>
/// RSA公鑰加密
/// </summary>
/// <param name="data"></param>
/// <param name="publicKey"></param>
/// <returns></returns>
public static byte[] RSAPublicEncrypt(byte[] data, string publicKeyFileName)
{
    X509Certificate2 x509Certificate2 = new X509Certificate2(publicKeyFileName);
    RSACryptoServiceProvider pubKey = (RSACryptoServiceProvider)x509Certificate2.PublicKey.Key;
    byte[] bys = pubKey.Encrypt(data, false);
    //string result = Convert.ToBase64String(bys);
    //return Encoding.UTF8.GetBytes(result);
    return bys;
}

私鑰解密

 /// <summary>
/// RSA私鑰解密
/// </summary>
/// <param name="data"></param>
/// <param name="privateKey"></param>
/// <returns></returns>
public static byte[] RSAPrivateDecrypt(byte[] data, string privateKeyFileName)
{
    string xml = PemToRSAKey(privateKeyFileName, true);//將pem密鑰轉為RSA密鑰
    RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
    rsa.FromXmlString(xml);
    return rsa.Decrypt(data, false);
}