using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;

namespace RSATest
{
    class Program
    {
        static void Main(string[] args)
        {
            string content = "这是测试内容!Hellow";
            Console.WriteLine(content);

            content = RSACrypto.Encrypt(content);
            Console.WriteLine(content);

            content = RSACrypto.Decrypt(content);
            Console.WriteLine(content);

            Console.Read();
        }
    }
}

using System;
using System.Text;
using System.Collections.Generic;
using System.Security.Cryptography;

namespace UNetwork
{
    /// <summary>
    /// RSA用途
    /// 作用一：私钥签名、公钥验签
    /// 作用二：公钥加密、私钥解密
    /// </summary>
    public static class RSACrypto
    {
        public static string publicKey;
        private static string privateKey;
        private static RSACryptoServiceProvider provider;

        static RSACrypto()
        {
            GenerateKey();
        }

        /// <summary>
        /// 生成密钥
        /// </summary>
        public static void GenerateKey()
        {
            try
            {
                provider = new RSACryptoServiceProvider();
                publicKey = provider.ToXmlString(false);
                privateKey = provider.ToXmlString(true);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
        }

        /// <summary>
        /// 加密
        /// </summary>
        public static string Encrypt(string content)
        {
            try
            {
                //设置密钥方式一
                //provider.ImportParameters(rsaParameters);
                //设置密钥方式二
                provider.FromXmlString(publicKey);
                byte[] bytes = Encoding.UTF8.GetBytes(content);
                bytes = provider.Encrypt(bytes, false);
                content = Convert.ToBase64String(bytes);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
            return content;
        }

        /// <summary>
        /// 解密
        /// </summary>
        public static string Decrypt(string content)
        {
            try
            {
                //设置密钥方式一
                //provider.ImportParameters(rsaParameters);
                //设置密钥方式二
                provider.FromXmlString(privateKey);
                byte[] bytes = Convert.FromBase64String(content);
                bytes = provider.Decrypt(bytes, false);
                content = Encoding.UTF8.GetString(bytes);
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
            }
            return content;
        }

        // 通过密钥指数和模数创建密钥参数对象
        public static RSAParameters CreateRSAParameters(string Exponent, string Modulus)
        {
            RSAParameters rsaParameters = new RSAParameters();
            rsaParameters.Exponent = FromHex(Exponent);//指数
            rsaParameters.Modulus = FromHex(Modulus);//模数
            return rsaParameters;
        }

        // 16进制的字符串转表示 转 byte[]
        public static byte[] FromHex(string hex)
        {
            if (string.IsNullOrEmpty(hex) || hex.Length % 2 != 0) throw new ArgumentException("not a hexidecimal string");

            List<byte> bytes = new List<byte>();

            for (int i = 0; i < hex.Length; i += 2)
            {
                bytes.Add(Convert.ToByte(hex.Substring(i, 2), 16));
            }
            return bytes.ToArray();
        }
    }
}

运行效果