RSACryptoGraphy, a set of methods was written by C#.

RSACryptoGraphy.cs

        /// <summary>
        /// Create public key/private key file, actually, the original certificates was modified to a XML file 
        /// 创建公钥/私钥文件，其实就是把原有的证书的内容修改成XML格式的
        /// </summary>
        public static void CreateCertificateKeyXML(string path, string key)
        {
            try
            {
                FileStream keyxml = new FileStream(path, FileMode.Create);
                StreamWriter sw = new StreamWriter(keyxml);
                sw.WriteLine(key);
                sw.Close();
                keyxml.Close();
            }
            catch
            {
                throw;
            }
        }

        /// <summary>
        /// Read public key/private key in terms of XML formation
        /// 读取公钥/私钥，以XML的形式
        /// </summary>
        public static string ReadCertificateKey(string path)
        {
            StreamReader reader = new StreamReader(path);
            string key = reader.ReadToEnd();
            reader.Close();
            return key;
        }

        /// <summary>
        /// RSA Encryption
        /// </summary>
        /// <param name="xmlPublicKey">public key</param>
        /// <param name="m_strEncryptString">unencrypted string</param>
        /// <returns>encrypted string</returns>
        public static string RSAEncrypt(string xmlPublicKey, string m_strEncryptString)
        {
            string str2;
            try
            {
                RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
                provider.FromXmlString(xmlPublicKey);
                byte[] bytes = new UnicodeEncoding().GetBytes(m_strEncryptString);
                str2 = Convert.ToBase64String(provider.Encrypt(bytes, false));
            }
            catch (Exception exception)
            {
                throw exception;
            }
            return str2;
        }

        /// <summary>
        /// RSA Decryption
        /// </summary>
        /// <param name="xmlPrivateKey">private key</param>
        /// <param name="m_strDecryptString">undecrypted string</param>
        /// <returns>decrypted result</returns>
        public static string RSADecrypt(string xmlPrivateKey, string m_strDecryptString)
        {
            string str2;
            try
            {
                RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
                provider.FromXmlString(xmlPrivateKey);
                byte[] rgb = Convert.FromBase64String(m_strDecryptString);
                byte[] buffer2 = provider.Decrypt(rgb, false);
                str2 = new UnicodeEncoding().GetString(buffer2);
            }
            catch (Exception exception)
            {
                throw exception;
            }
            return str2;
        }

    static void Main(string[] args)
    {

        RSACryptoServiceProvider provider = new RSACryptoServiceProvider();
        CreateCertificateKeyXML("C:\\Users\\victor\\Desktop\\public_key.der", provider.ToXmlString(false));
        CreateCertificateKeyXML("C:\\Users\\victor\\Desktop\\private_key.p12", provider.ToXmlString(true));

        string public_key = ReadCertificateKey("C:\\Users\\victor\\Desktop\\public_key.der");
        string private_key = ReadCertificateKey("C:\\Users\\victor\\Desktop\\private_key.p12");

        string hello = "hello, world!";
        string cipherHello = RSAEncrypt(public_key, hello);
        Console.WriteLine(cipherHello);

        string plainHello = RSADecrypt(private_key, cipherHello);
        Console.WriteLine(plainHello);


        Console.ReadKey();
    }