using System;

using System.Text;

using Org.BouncyCastle.Crypto;

using Org.BouncyCastle.Crypto.Parameters;

using Org.BouncyCastle.Security;

using Org.BouncyCastle.Crypto.Generators;

using Org.BouncyCastle.Asn1.X509;

using Org.BouncyCastle.Asn1.Pkcs;

using Org.BouncyCastle.X509;

using Org.BouncyCastle.Pkcs;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var dataToSign="challengeString";

        RsaKeyPairGenerator g = new RsaKeyPairGenerator();

        g.Init(new KeyGenerationParameters(new SecureRandom(), 2048));

​

        AsymmetricCipherKeyPair pair = g.GenerateKeyPair();

        PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(pair.Private);

        byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetDerEncoded();

        string serializedPrivate = Convert.ToBase64String(serializedPrivateBytes);

        SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(pair.Public);

        byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();

        string serializedPublic = Convert.ToBase64String(serializedPublicBytes);

        Console.WriteLine("Private {0} {1}", serializedPrivate.Length, serializedPrivate);

        Console.WriteLine("Public {0} {1}", serializedPublic.Length, serializedPublic);

        var signer = SignerUtilities.GetSigner("RSA");

        signer.Init(true, pair.Private);

        byte[] dts = Encoding.UTF8.GetBytes(dataToSign);

        signer.BlockUpdate(dts, 0, dataToSign.Length);

        var signature = signer.GenerateSignature();

        var signed =  Convert.ToBase64String(signature);

        Console.WriteLine("Semnat {0}", signed);

​

    }

}