RSA uses

RSA uses

Today, with my colleagues in debugging TCP communications together when at the RSA private key to decrypt this, so I really spent a lot of thought.
Such a process is generally, when using a fixed terminal login password encryption des transmission data, after confirming the platform after receiving the login information, returns a string,
the string is a string rsa use of public key cryptography, as subsequent communications des use of passwords. JAVA platform is developed using the public key and private key files are
stored in a terminal. But this is pem file formats, and the use of public key certificate of the way, sending the debugging uses public key cryptography to the platform, the platform can all be decrypted.
But the platform sends back decrypted public key encryption is not normal. Find information which is not to say, finally resolved. Here to do a record, but also to be shared.
Using a third-party libraries: BouncyCastle, NuGet can be used to install.
The first is the system conversion RSA keys and Pem key.

/// <summary>
        /// Pem密钥转RSA密钥
        /// </summary>
        /// <param name="pemKey">Pem密钥</param>
        /// <param name="isPrivateKey">是否是私钥</param>
        /// <returns>RSA密钥</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私钥
            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公钥
            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密钥转Pem密钥
        /// </summary>
        /// <param name="RSAKey">RSA密钥</param>
        /// <param name="isPrivateKey">是否是私钥</param>
        /// <returns>Pem密钥</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私钥
            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公钥
            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;
        }

Public key cryptography, a certificate to open the key file pem

 /// <summary>
/// RSA公钥加密
/// </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;
}

Private key to decrypt

 /// <summary>
/// RSA私钥解密
/// </summary>
/// <param name="data"></param>
/// <param name="privateKey"></param>
/// <returns></returns>
public static byte[] RSAPrivateDecrypt(byte[] data, string privateKeyFileName)
{
    string xml = PemToRSAKey(privateKeyFileName, true);//将pem密钥转为RSA密钥
    RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
    rsa.FromXmlString(xml);
    return rsa.Decrypt(data, false);
}