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： 
 
   
     
       
       
     
   

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; 

            ///

 
            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： 
///

 
        ///  
        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： 
///

 
        /// 输入值. 
        ///  
        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： 
///

 
        /// 经过加密后的字符串. 
        ///  
        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”]; 
        } 

        ///

 
        /// 输入值. 
        ///  
        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); 
        } 

        ///

 
        ///  
        private tripledescryptoserviceprovider getcryptoprovider() 
        { 
            tripledescryptoserviceprovider provider = new tripledescryptoserviceprovider(); 

            provider.iv = convert.frombase64string(iv); 
            provider.key = convert.frombase64string(key); 

            return provider; 

        } 

        ///

 
        /// 经过加密后的字符串. 
        ///  
        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()); 
        } 
    } 
}