des是常用的对称加密解密方法，下面是C#下的核心代码
/// <summary>
/// 进行DES加密。
/// </summary>
/// <param name="pToEncrypt">要加密的字符串。</param>
/// <param name="sKey">密钥，且必须为8位。</param>
/// <returns>以Base64格式返回的加密字符串。</returns>
public string Encrypt(string pToEncrypt, string sKey)
{
using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
{
byte[] inputByteArray = Encoding.UTF8.GetBytes(pToEncrypt);
des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
cs.Close();
}
string str = Convert.ToBase64String(ms.ToArray());
ms.Close();
return str;
}
}
/// <summary>
/// 进行DES解密。
/// </summary>
/// <param name="pToDecrypt">要解密的以Base64</param>
/// <param name="sKey">密钥，且必须为8位。</param>
/// <returns>已解密的字符串。</returns>
public string Decrypt(string pToDecrypt, string sKey)
{
byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);
using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
{
des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(inputByteArray, 0, inputByteArray.Length);
cs.FlushFinalBlock();
cs.Close();
}
string str = Encoding.UTF8.GetString(ms.ToArray());
ms.Close();
return str;
}
}
在代码中还要应用个类库：using System.Security.Cryptography;
des加密在java中也有相应的算法，而且和.net下的一致，可以用于不同语言编写的系统的加解密调用
下面一段为java下的des加密，C#下的解密小例子：
java中使用DES加密，C#中解密过程如下，
java中的加密代码，DES.java类代码：
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package welcome;
import javax.crypto.*;
import javax.crypto.*;
import java.io.UnsupportedEncodingException;
import java.security.spec.*;
import javax.crypto.spec.*;
public class DES {
public DES()
{
}
public String encrypt(String str) {
byte[] enc = null;
try {
enc = desEncrypt(str, "abcdefgh");
}
catch (Exception ex) {
}
return new sun.misc.BASE64Encoder().encode(enc);
}
public static byte[] desEncrypt(String message, String key) throws Exception {
Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
return cipher.doFinal(message.getBytes("UTF-8"));
}
}
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调用示例代码，jsp1.jsp:
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<%@ page contentType="text/html; charset=gb2312" %>
<jsp:useBean id="DES" scope="page" class="welcome.DES" />
<html>
<head><title>DES File</title></head>
<body bgcolor="#FFFFFF">
<div align="center"><center>
<%
String Test = request.getParameter("Test");
if(Test==null || Test.equals("")) {
%>
<form name="form" method="post" action="jsp1.jsp">
<input type="text" name="Test" size="25" value=""/>
<input type="submit" name="button" value=" 确定 "/>
</form>
<%
}else{
out.println("加密前的数据："+Test +"<br/>");
out.println("加密后的数据："+DES.encrypt(Test) +"<br/><a href=’http://localhost:9003/JiaMi.aspx?str="+DES.encrypt(Test)+"’ target=_blank>连接</a>");
}
%>
</center></div>
</body>
</html>
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C#中的解码函数：
/// <summary>
/// 进行DES解密。
/// </summary>
/// <param name="pToDecrypt">要解密的以Base64</param>
/// <returns>已解密的字符串。</returns>
public string Decrypt(string pToDecrypt,string sKey)
{
byte[] inputByteArray = Convert.FromBase64String(pToDecrypt);
using(DESCryptoServiceProvider des = new DESCryptoServiceProvider())
{
des.Key=ASCIIEncoding.ASCII.GetBytes(sKey);
des.IV=ASCIIEncoding.ASCII.GetBytes(sKey);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
using(CryptoStream cs = new CryptoStream(ms,des.CreateDecryptor(),CryptoStreamMode.Write))
{
cs.Write(inputByteArray,0,inputByteArray.Length);
cs.FlushFinalBlock();
cs.Close();
}
string str = Encoding.UTF8.GetString(ms.ToArray());
ms.Close();
return str;
}
}
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调用：
string str = Page.Request.QueryString["str"];
Page.Response.Write("得到的为："+Decrypt(str,"abcdefgh"));