RSA public key encryption in C#

crypto.cs

using System;
using System.Diagnostics;
using System.Security.Cryptography;
using System.Text;

namespace Crtypto
{
    class Program
    {
        static void Main(string[] args)
        {
            // generating public/private keys
            //
            //Debug.WriteLine("private: " + RSA.ToXmlString(true));
            //Debug.WriteLine("public: " + RSA.ToXmlString(false));

            var publicKey =
                "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";

            var privateKey =
                "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent><P>/aULPE6jd5IkwtWXmReyMUhmI/nfwfkQSyl7tsg2PKdpcxk4mpPZUdEQhHQLvE84w2DhTyYkPHCtq/mMKE3MHw==</P><Q>3WV46X9Arg2l9cxb67KVlNVXyCqc/w+LWt/tbhLJvV2xCF/0rWKPsBJ9MC6cquaqNPxWWEav8RAVbmmGrJt51Q==</Q><DP>8TuZFgBMpBoQcGUoS2goB4st6aVq1FcG0hVgHhUI0GMAfYFNPmbDV3cY2IBt8Oj/uYJYhyhlaj5YTqmGTYbATQ==</DP><DQ>FIoVbZQgrAUYIHWVEYi/187zFd7eMct/Yi7kGBImJStMATrluDAspGkStCWe4zwDDmdam1XzfKnBUzz3AYxrAQ==</DQ><InverseQ>QPU3Tmt8nznSgYZ+5jUo9E0SfjiTu435ihANiHqqjasaUNvOHKumqzuBZ8NRtkUhS6dsOEb8A2ODvy7KswUxyA==</InverseQ><D>cgoRoAUpSVfHMdYXW9nA3dfX75dIamZnwPtFHq80ttagbIe4ToYYCcyUz5NElhiNQSESgS5uCgNWqWXt5PnPu4XmCXx6utco1UVH8HGLahzbAnSy6Cj3iUIQ7Gj+9gQ7PkC434HTtHazmxVgIR5l56ZjoQ8yGNCPZnsdYEmhJWk=</D></RSAKeyValue>";
            
            var testData = Encoding.UTF8.GetBytes("testing");

            using ( var rsa = new RSACryptoServiceProvider(1024))
            {
                
                try
                {
                    

                    // client encrypting data with public key issued by server
                    //
                    rsa.FromXmlString(publicKey);

                    
                    var encryptedData = rsa.Encrypt(testData, true);

                    
                    var base64Encrypted = Convert.ToBase64String(encryptedData);
                    Debug.WriteLine(base64Encrypted);

                    // server decrypting data with private key
                    //
                    rsa.FromXmlString(privateKey);

                    var resultBytes = Convert.FromBase64String(base64Encrypted);
                    var decryptedBytes = rsa.Decrypt(resultBytes, true);
                    var decryptedData = Encoding.UTF8.GetString(decryptedBytes);
                    Debug.WriteLine(decryptedData);

                }
                finally
                {
                    rsa.PersistKeyInCsp = false;
                }

            }
        }
    }
}

Why exactly do you need ToBase64String and FromBase64String?

I've seen some people saying this is necessary: http://stackoverflow.com/a/2164186/145349

Can you confirm this?

@fjsj it's good to use Base64 encoding to encode a byte sequence to a string instead of Unicode encoding, because not every byte sequence has a Unicode representation. In this example, when the RSA encrypts the input bytes you can't be sure if the output bytes have a Unicode representation, but you can be sure that they have a Base64 representation.

Thanks for code!