using System;

using System.Security.Cryptography;

​

public class Program

{

    static void Main(string[] args)

    {

        var(publicKey, privateKey) = GenerateKeys(2048);

        var data = new byte[]{1, 2, 3};

        var signedData = Sign(data, privateKey);

        var isValid = VerifySignature(data, signedData, publicKey);

    }

​

    static (RSAParameters publicKey, RSAParameters privateKey) GenerateKeys(int keyLength)

    {

        using (var rsa = RSA.Create())

        {

            rsa.KeySize = keyLength;

            return (publicKey: rsa.ExportParameters(includePrivateParameters: false), privateKey: rsa.ExportParameters(includePrivateParameters: true));

        }

    }

​

    static byte[] Sign(byte[] data, RSAParameters privateKey)

    {

        using (var rsa = RSA.Create())

        {

            rsa.ImportParameters(privateKey);

            // the hash to sign

            byte[] hash;

            using (var sha256 = SHA256.Create())

            {

                hash = sha256.ComputeHash(data);

            }

​

            var rsaFormatter = new RSAPKCS1SignatureFormatter(rsa);

            rsaFormatter.SetHashAlgorithm("SHA256");

            return rsaFormatter.CreateSignature(hash);

        }

    }

​

    private static bool VerifySignature(byte[] data, byte[] signature, RSAParameters publicKey)

    {

        using (var rsa = RSA.Create())

        {

            rsa.ImportParameters(publicKey);

            // the hash to sign

            byte[] hash;

            using (var sha256 = SHA256.Create())

            {

                hash = sha256.ComputeHash(data);

            }

​

            var rsaFormatter = new RSAPKCS1SignatureDeformatter(rsa);

            rsaFormatter.SetHashAlgorithm("SHA256");

            return rsaFormatter.VerifySignature(hash, signature);

        }

    }

}