Asp.net,C# 加密解密字符串

首先在web.config | app.config 文件下增加如下代码：
<?xml version="1.0"?>
  <configuration>
    <appSettings>
      <add key="IV" value="SuFjcEmp/TE="/>
      <add key="Key" value="KIPSToILGp6fl+3gXJvMsN4IajizYBBT"/>
    </appSettings>
  </configuration>



IV:加密算法的初始向量。

Key：加密算法的密钥。



接着新建类CryptoHelper,作为加密帮助类。

首先要从配置文件中得到IV 和Key。所以基本代码如下：
public class CryptoHelper
        {
            //private readonly string IV = "SuFjcEmp/TE=";
            private readonly string IV = string.Empty;
            //private readonly string Key = "KIPSToILGp6fl+3gXJvMsN4IajizYBBT";
            private readonly string Key = string.Empty;

            /// <summary>
            ///构造函数
            /// </summary>
            public CryptoHelper()
            {
                IV = ConfigurationManager.AppSettings["IV"];
                Key = ConfigurationManager.AppSettings["Key"];
            }
        }





注意添加System.Configuration.dll程序集引用。



在获得了IV 和Key 之后，需要获取提供加密服务的Service 类。

在这里，使用的是System.Security.Cryptography; 命名空间下的TripleDESCryptoServiceProvider类。

获取TripleDESCryptoServiceProvider 的方法如下：
/// <summary>
        /// 获取加密服务类
        /// </summary>
        /// <returns></returns>
        private TripleDESCryptoServiceProvider GetCryptoProvider()
        {
            TripleDESCryptoServiceProvider provider = new TripleDESCryptoServiceProvider();

            provider.IV = Convert.FromBase64String(IV);
            provider.Key = Convert.FromBase64String(Key);

            return provider;
        }



TripleDESCryptoServiceProvider 两个有用的方法

CreateEncryptor:创建对称加密器对象ICryptoTransform.

CreateDecryptor:创建对称解密器对象ICryptoTransform

加密器对象和解密器对象可以被CryptoStream对象使用。来对流进行加密和解密。

cryptoStream 的构造函数如下：
public CryptoStream(Stream stream, ICryptoTransform transform, CryptoStreamMode mode);

使用transform 对象对stream 进行转换。



完整的加密字符串代码如下：
/// <summary>
        /// 获取加密后的字符串
        /// </summary>
        /// <param name="inputValue">输入值.</param>
        /// <returns></returns>
        public string GetEncryptedValue(string inputValue)
        {
            TripleDESCryptoServiceProvider provider = this.GetCryptoProvider();

            // 创建内存流来保存加密后的流
            MemoryStream mStream = new MemoryStream();

            // 创建加密转换流
            CryptoStream cStream = new CryptoStream(mStream,
            provider.CreateEncryptor(), CryptoStreamMode.Write);

            // 使用UTF8编码获取输入字符串的字节。
            byte[] toEncrypt = new UTF8Encoding().GetBytes(inputValue);

            // 将字节写到转换流里面去。
            cStream.Write(toEncrypt, 0, toEncrypt.Length);
            cStream.FlushFinalBlock();

            // 在调用转换流的FlushFinalBlock方法后，内部就会进行转换了,此时mStream就是加密后的流了。
            byte[] ret = mStream.ToArray();

            // Close the streams.
            cStream.Close();
            mStream.Close();

            //将加密后的字节进行64编码。
            return Convert.ToBase64String(ret);
        }





解密方法也类似：
/// <summary>
        /// 获取解密后的值
        /// </summary>
        /// <param name="inputValue">经过加密后的字符串.</param>
        /// <returns></returns>
        public string GetDecryptedValue(string inputValue)
        {
            TripleDESCryptoServiceProvider provider = this.GetCryptoProvider();

            byte[] inputEquivalent = Convert.FromBase64String(inputValue);

            // 创建内存流保存解密后的数据
            MemoryStream msDecrypt = new MemoryStream();

            // 创建转换流。
            CryptoStream csDecrypt = new CryptoStream(msDecrypt,
                                                        provider.CreateDecryptor(),
                                                        CryptoStreamMode.Write);

            csDecrypt.Write(inputEquivalent, 0, inputEquivalent.Length);

            csDecrypt.FlushFinalBlock();
            csDecrypt.Close();

            //获取字符串。
            return new UTF8Encoding().GetString(msDecrypt.ToArray());
        }





完整的CryptoHelper代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;
using System.Configuration;

namespace WindowsFormsApplication1
{
    public class CryptoHelper
    {
        //private readonly string IV = "SuFjcEmp/TE=";
        private readonly string IV = string.Empty;
        //private readonly string Key = "KIPSToILGp6fl+3gXJvMsN4IajizYBBT";
        private readonly string Key = string.Empty;

        public CryptoHelper()
        {
            IV = ConfigurationManager.AppSettings["IV"];
            Key = ConfigurationManager.AppSettings["Key"];
        }

        /// <summary>
        /// 获取加密后的字符串
        /// </summary>
        /// <param name="inputValue">输入值.</param>
        /// <returns></returns>
        public string GetEncryptedValue(string inputValue)
        {
            TripleDESCryptoServiceProvider provider = this.GetCryptoProvider();

            // 创建内存流来保存加密后的流
            MemoryStream mStream = new MemoryStream();

            // 创建加密转换流
            CryptoStream cStream = new CryptoStream(mStream,

            provider.CreateEncryptor(), CryptoStreamMode.Write);
            // 使用UTF8编码获取输入字符串的字节。
            byte[] toEncrypt = new UTF8Encoding().GetBytes(inputValue);

            // 将字节写到转换流里面去。
            cStream.Write(toEncrypt, 0, toEncrypt.Length);
            cStream.FlushFinalBlock();

            // 在调用转换流的FlushFinalBlock方法后，内部就会进行转换了,此时mStream就是加密后的流了。
            byte[] ret = mStream.ToArray();

            // Close the streams.
            cStream.Close();
            mStream.Close();

            //将加密后的字节进行64编码。
            return Convert.ToBase64String(ret);
        }

        /// <summary>
        /// 获取加密服务类
        /// </summary>
        /// <returns></returns>
        private TripleDESCryptoServiceProvider GetCryptoProvider()
        {
            TripleDESCryptoServiceProvider provider = new TripleDESCryptoServiceProvider();

            provider.IV = Convert.FromBase64String(IV);
            provider.Key = Convert.FromBase64String(Key);

            return provider;

        }

        /// <summary>
        /// 获取解密后的值
        /// </summary>
        /// <param name="inputValue">经过加密后的字符串.</param>
        /// <returns></returns>
        public string GetDecryptedValue(string inputValue)
        {
            TripleDESCryptoServiceProvider provider = this.GetCryptoProvider();
            byte[] inputEquivalent = Convert.FromBase64String(inputValue);

            // 创建内存流保存解密后的数据
            MemoryStream msDecrypt = new MemoryStream();

            // 创建转换流。
            CryptoStream csDecrypt = new CryptoStream(msDecrypt,
            provider.CreateDecryptor(),
            CryptoStreamMode.Write);

            csDecrypt.Write(inputEquivalent, 0, inputEquivalent.Length);
            csDecrypt.FlushFinalBlock();

            csDecrypt.Close();

            //获取字符串。
            return new UTF8Encoding().GetString(msDecrypt.ToArray());
        }
    }
}