C#rsa algorithm implementation + How to convert the public key into PEM format for object-c use

. NET, for security reasons, the RSACryptoServiceProvider class, which only has both a public and private key to decrypt. The reason is that the public key is public and will be held by multiple people. Such data transmission is not secure. C#rsa private key encryption, public key decryption error reason!

Using RSA algorithm to generate public and private key methods in C #:

After the public key is generated, it is saved under the folder with the same name, such as:

Public key generation, where the path is "Rsa\rsa\bin\debug"

 
Using System;
Using System.IO;
Using System.Security.Cryptography;//must reference

Namespace RSA
{
     Class Program
     {
         Static void Main(string[] args)
         {
             RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
             Using (StreamWriter writer = new StreamWriter("PrivateKey.xml")) //This file should be kept secret...
             {
                 writer.WriteLine(rsa.ToXmlString(true));
             }
             Using (StreamWriter writer = new StreamWriter("PublicKey.xml"))
            {
                 writer.WriteLine(rsa.ToXmlString(false));
            }
         }
     }
}

Method Two:

Public static void GKEY()//(computer) generates a key GKEY(generate key),generate the RSA public and private keys
     {
         Using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
         {
             String publicKey = rsa.ToXmlString(false); // public key
             String privateKey = rsa.ToXmlString(true); // private key
         }
     }

Direct breakpoint mode copy public key out

RSA Cryptographic Decryption Class

#region RSA
    /// <summary>
    /// RSA encryption
    /// </summary>
    /// <param name="publickey"></param>
    /// <param name="content"></param>
    /// <returns></returns>
    Public static string RSAEncrypt(string publickey, string content)
    {
        publickey = @ "<RSAKeyValue> <Modulus> 0wE26IHp4U9OLtPhJ + fT8ej6aWORFP8pd ++ MjUuhkQQm / zhcImbxQbjxtSAftz + kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt + 4UDMwKakgZqFoapDuwjKlTErFvKCyKCs + qN9OZvZwKWk = </ Modulus> <Exponent> AQAB </ Exponent> </ RSAKeyValue>";
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        Byte[] cipherbytes;
        rsa.FromXmlString(publickey);
        Cipherbytes = rsa.Encrypt(Encoding.UTF8.GetBytes(content), false);

        Return Convert.ToBase64String(cipherbytes);

    }

    /// <summary>
    /// RSA decryption
    /// </summary>
    /// <param name="privatekey"></param>
    /// <param name="content"></param>
    /// <returns></returns>
    Public static string RSADecrypt(string privatekey, string content)
    {
        privatekey = @ "<RSAKeyValue> <Modulus> 0wE26IHp4U9OLtPhJ + fT8ej6aWORFP8pd ++ MjUuhkQQm / zhcImbxQbjxtSAftz + kkDwGDFJpSldQPyigOGcUx7PofTc6VhiFik9E9SsxV9n0iEEtqUndDfmBJfPAWt + 4UDMwKakgZqFoapDuwjKlTErFvKCyKCs + qN9OZvZwKWk = </ Modulus> <Exponent> AQAB </ Exponent> <P> 8Ei6NIsZtgV3DQjuGHfGLS6o1O + IUXxzjqLxdMm77yhEPUxR9YPIxODJ2VVTddXSAHxViJJt30yJ7JhVz6cpQw == </ P> < Q> 4M49NrmalgVQFMsea2RMB1qN8fAPfIw5G9q9hzsLcWSCmkeRRIQlvPYflVEKAYKiDVVzENETbnnduFXWBABx4w == </ Q> <DP> t + JQbemN0Zi5FQaif6MZzHYKynpNTl75aE0Wj5Pa + RlNr8N6bXNe8Bw / HM2Jw4HQ5oJASvYUk3DVlHS4JuP8VQ == </ DP> <DQ> lT62iv9brp9mU / epgVh71SH8PJPIZEJfo6tryjyb0zMMNcqvmZI1z6aCv0mm3 + vPFBUXqCF1yhFj7n4l8FAvSw == </ DQ> <InverseQ> flrvgxHvf4l + fdymEVDgKjsfGqshOpppoNgZj9kpeWBto3o8z ++ Ki6eSLQT3nVnpx2QCZeTWkxTED4nhSLKscw == </ InverseQ> <D> cQTCg1Eqk7sltmFYxUYgOP / AOPjSufteG9acYwYymPkvZh6rAuY + rSRBmvGE62NUYskzuB / gM6iG2 / 2HrA5SixfNgCvZ + nsK + kX5pzQRsYdD71ViQW0hOanXwj45I2zHRgBiuTtCUP0fs5pISmQkaeJkDL5pO2l + wvlgl + wunj0 = </ D> </ RSAKeyValue> ";
        RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
        Byte[] cipherbytes;
        rsa.FromXmlString(privatekey);
        Cipherbytes = rsa.Decrypt(Convert.FromBase64String(content), false);

        Return Encoding.UTF8.GetString(cipherbytes);
    }
    #endregion 

How do I convert the public key to PEM format in XML format?

Need to rely on a third-party library called Bouncycastle
The code to get the installation package online is as follows:

PM > Install-package bouncycastle

If you don't know how to open the vs2013 console, look below
Tips: Open the VS2013 console method

Open the VS2013 console method. png

Install third-party library success diagram. png method one: Online conversion

Click here to jump >> online conversion

How do I transfer the key XML format and PEM format? "Tips: Here's the key, the public key uses a different method." First, convert the XML format key to PEM

Public static void XMLConvertToPEM()//XML format key to PEM
     {
         Var rsa2 = new RSACryptoServiceProvider();
         Using (var sr = new StreamReader("e:\\PrivateKey.xml"))
         {
             rsa2.FromXmlString(sr.ReadToEnd());
         }
         Var p = rsa2.ExportParameters(true);

         Var key = new RsaPrivateCrtKeyParameters(
             New BigInteger(1, p.Modulus), new BigInteger(1, p.Exponent), new BigInteger(1, p.D),
             New BigInteger(1, p.P), new BigInteger(1, p.Q), new BigInteger(1, p.DP), new BigInteger(1, p.DQ),
             New BigInteger(1, p.InverseQ));

         Using (var sw = new StreamWriter("e:\\PrivateKey.pem"))
         {
             Var pemWriter = new Org.BouncyCastle.OpenSsl.PemWriter(sw);
             pemWriter.WriteObject(key);
         }
     }

One, the PEM format key to XML

 
 
Public static void PEMConvertToXML()//PEM format key to XML
    {
        AsymmetricCipherKeyPair keyPair;
        Using (var sr = new StreamReader("e:\\PrivateKey.pem"))
        {
            Var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(sr);
            keyPair = (AsymmetricCipherKeyPair)pemReader.ReadObject();
        }
        Var key = (RsaPrivateCrtKeyParameters)keyPair.Private;
        Var p = 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(),
        };
        Var rsa = new RSACryptoServiceProvider();
        rsa.ImportParameters(p);
        Using (var sw = new StreamWriter("e:\\PrivateKey.xml"))
        {
            sw.Write(rsa.ToXmlString(true));
        }
    } 

Please click: reference

Other "Tips: Pending Test"

Generation and use of CER and PFX certificates

CER and PFX certificates. png
Generate public key. png

C#rsa algorithm Implementation + How to convert the public key to PEM format for object-c use