C#使用证书做数字签名，RSA加密解密，X509【.NET】

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Threading.Tasks;

/************************
 * 说明：接口数字签名类
 * 创建人：原道楠
 * 创建时间：2016-5-19
 * **********************/
namespace Common.PayMentPlatform
{
    /// <summary>
    /// 接口数字签名类
    /// </summary>
    public class Signature
    {
        /// <summary>
        /// 数字签名
        /// </summary>
        /// <param name="plaintext">明文</param>
        /// <returns>签名</returns>
        public static string HashAndSignString(string plaintext)
        {
            //根据证书友好名称查找证书
            X509Certificate2 x509Certificate2 = GetX509Certificate2();
            if (x509Certificate2 != null)
            {
                UnicodeEncoding ByteConverter = new UnicodeEncoding();
                //将明文转byte[]
                byte[] dataToEncrypt = ByteConverter.GetBytes(plaintext);
                //将证书中私钥转为rsa对象
                RSACryptoServiceProvider RSAalg = x509Certificate2.PrivateKey as RSACryptoServiceProvider;
                //使用SHA1哈希进行摘要算法，
                byte[] encryptedData = RSAalg.SignData(dataToEncrypt, new SHA1CryptoServiceProvider());
                //得到签名
                string signStr = Convert.ToBase64String(encryptedData);
                RSAalg.Clear();
                RSAalg.Dispose();
                return signStr;
            }
            else
            {
                //找不到证书  记录日志到本地，没有的可以删掉
                Helper.WriteLogContent("签名时在系统中找不到证书,明文：" + plaintext);
                return "";
            }
        }

        /// <summary>
        /// 验证签名
        /// </summary>
        /// <param name="plaintext">明文</param>
        /// <param name="signedData">签名</param>
        /// <returns></returns>
        public static bool VerifySigned(string plaintext, string signedData)
        {
            //根据证书友好名称查找证书
            X509Certificate2 x509Certificate2 = GetX509Certificate2();
            if (x509Certificate2 != null)
            {
                //将证书公钥转为rsa对象
                RSACryptoServiceProvider RSAalg = x509Certificate2.PublicKey.Key as RSACryptoServiceProvider;
                UnicodeEncoding ByteConverter = new UnicodeEncoding();
                //将明文转byte[]
                byte[] dataToVerifyBytes = ByteConverter.GetBytes(plaintext);
                //将签名转byte[]
                byte[] signedDataBytes = Convert.FromBase64String(signedData);
                //验证签名
                bool isSuccess = RSAalg.VerifyData(dataToVerifyBytes, new SHA1CryptoServiceProvider(), signedDataBytes);
                RSAalg.Clear();
                RSAalg.Dispose();
                return isSuccess;
            }
            else
            {
                //找不到证书  记录日志到本地，没有的可以删掉
                Helper.WriteLogContent( "验证签名时在系统中找不到证书,明文：" + plaintext + ",密文：" + signedData);
                return false;
            }
        }

        /// <summary>
        /// 获取证书对象 （楼主这用的是物理路径获取证书)
        /// </summary>
        /// <returns>为null即找不到证书</returns>
        public static X509Certificate2 GetX509Certificate2()
        {//证书路径和密码放到了配置文件里   第一个参数是证书的绝对路径，第二个是证书密码，没有就空
            return new X509Certificate2(ConfigurationManager.AppSettings["CerPath"], ConfigurationManager.AppSettings["CerPassword"]);
           
        }
    }
}