3DES又称Triple DES，是DES加密算法的一种模式，它使用3条56位的密钥对3DES数据进行三次加密。
加密过程为：C=Ek3(Dk2(Ek1(P)))
解密过程为：P=Dk1(EK2(Dk3(C)))
C#已经对3DES加密进行了封装，可使用System.Security.Cryptography中的TripleDESCryptoServiceProvider类来实现，项目的需求是采用24位KEY、ECB模式来对应java平台的加解密。其中还涉及unix时间戳，MD5散列，base64编码的综合使用。
开始的时候对HttpWebRequest认识不深，在对base64的编码“+”符号上犯错，POST与GET请求中“+”【%2B】会出现替换的不同，以至于平台解析不成功。以下是测试后的代码：
using System;
using System.Text;
using System.Security.Cryptography;
namespace TestProject
{
///
/// 数据加密工具类
///
public sealed class EncryptionUtils
{
#region DES解密
//3DES(DESede>Jave)24位KEY
private const string ENCRYPT_KEY = "3DES_MD5_Timestamp123456";
///
/// 3DES加密
/// base64小细节，当使用get请求时，base64生成字符中有“+”号，
/// 注意需要转换“%2B”，否则会被替换成空格。POST不存在
/// while (str.IndexOf('+') != -1) {
/// str = str.Replace("+","%2B");
// }
///
public static string Encrypt3DES (string fValue)
{
if(string.IsNullOrEmpty(fValue)){
return fValue;
}
try{
Encoding encoding = Encoding.GetEncoding("UTF-8");
var DES = new TripleDESCryptoServiceProvider();
DES.Key = encoding.GetBytes(ENCRYPT_KEY);
DES.Mode = CipherMode.ECB;
ICryptoTransform DESEncrypt = DES.CreateEncryptor();
byte[] Buffer = encoding.GetBytes(fValue);
return Convert.ToBase64String(DESEncrypt.TransformFinalBlock(Buffer, 0, Buffer.Length));
}catch(Exception ex){
Log.Error("Encrypt3DES>>"+ex.Message);
return string.Empty;
}
}
///
/// 3DES解密
///
/// 解密串
/// 加密串
public static string Decrypt3DES (string a_strString)
{
if(string.IsNullOrEmpty(a_strString)){
return a_strString;
}
try {
var DES = new TripleDESCryptoServiceProvider ();
DES.Key = ASCIIEncoding.ASCII.GetBytes (ENCRYPT_KEY);
DES.Mode = CipherMode.ECB;
DES.Padding = System.Security.Cryptography.PaddingMode.PKCS7;
ICryptoTransform DESDecrypt = DES.CreateDecryptor ();
byte[] Buffer = Convert.FromBase64String (a_strString);
return ASCIIEncoding.ASCII.GetString (DESDecrypt.TransformFinalBlock (Buffer, 0, Buffer.Length));
} catch (Exception e) {
Log.Error("Decrypt3DES>>"+e.Message);
return string.Empty;
}
}
#endregion
#region 基础方法
///
/// MD5编码
///
public static string MD5(string str){
if(string.IsNullOrEmpty(str)){
return str;
}
var md5 = new MD5CryptoServiceProvider();
var datas = Encoding.UTF8.GetBytes(str);
var hash = md5.ComputeHash(datas);
md5.Clear();
str = string.Empty;
//把MD5所得用16进制小写的字符串形式，让函数返回一个32字节长的可打印字符串。
for(int i =0;i
str += hash[i].ToString("X").PadLeft(2,'0');
}
return str;
}
///
/// 并进行base64编码
///
public static string ToBase64String(string str){
if(string.IsNullOrEmpty(str)){
return string.Empty;
}
return Convert.ToBase64String(Encoding.UTF8.GetBytes(str));
}
///
/// unix时间戳
///
public static string GetTimestamp()
{
DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime (new System.DateTime (1970, 1, 1, 0, 0, 0, 0));
DateTime nowTime = DateTime.Now;
long unixTime = (long)Math.Round ((nowTime - startTime).TotalMilliseconds, MidpointRounding.AwayFromZero);
return unixTime.ToString ();
}
#endregion
}
public static class Log
{
public static void Error(string msg)
{
Console.WriteLine ("Error"+msg);
}
public static void Info(string msg)
{
Console.WriteLine ("Info"+msg);
}
}
}测试代码：
public static void Main (string[] args)
{
Console.WriteLine ("Hello World!");
string line = string.Empty;
while ((line = Console.ReadLine ()) != null) {
var encrypt = EncryptionUtils.Encrypt3DES (line);
var decrypt = EncryptionUtils.Decrypt3DES (encrypt);
Log.Info ("输入>>" + line);
Log.Info ("密文>>" + encrypt);
Log.Info ("明文>>" + decrypt);
}
}
