代碼：
import java.security.*;
import javax.crypto.*;
public class Crypt 
{
private static String Algorithm="DES"; //定義 加密算法,可用 DES,DESede,Blowfish
static boolean debug = false;
static{
Security.addProvider(new com.sun.crypto.provider.SunJCE());
}
//生成密鑰, 注意此步驟時間比較長
public static byte[] getKey() throws Exception{
KeyGenerator keygen = KeyGenerator.getInstance(Algorithm);
SecretKey deskey = keygen.generateKey();
if (debug)
System.out.println("生成密鑰:"+byte2hex(deskey.getEncoded()));
return deskey.getEncoded();
}
//加密
public static byte[] encode(byte[] input,byte[] key) throws Exception{
SecretKey deskey = new javax.crypto.spec.SecretKeySpec(key,Algorithm);
if (debug){
System.out.println("加密前的二進串:"+byte2hex(input));
System.out.println("加密前的字符串:"+new String(input));
}
Cipher c1 = Cipher.getInstance(Algorithm);
c1.init(Cipher.ENCRYPT_MODE,deskey);
byte[] cipherByte=c1.doFinal(input);
if (debug)
System.out.println("加密后的二進串:"+byte2hex(cipherByte));
return cipherByte;
}
//解密
public static byte[] decode(byte[] input,byte[] key) throws Exception{
SecretKey deskey = new javax.crypto.spec.SecretKeySpec(key,Algorithm);
if (debug)
System.out.println("解密前的信息:"+byte2hex(input));
Cipher c1 = Cipher.getInstance(Algorithm);
c1.init(Cipher.DECRYPT_MODE,deskey);
byte[] clearByte=c1.doFinal(input);
if (debug){
System.out.println("解密后的二進串:"+byte2hex(clearByte));
System.out.println("解密后的字符串:"+(new String(clearByte)));
}
return clearByte;
}
//md5()信息摘要, 不可逆
public static byte[] md5(byte[] input) throws Exception{
java.security.MessageDigest alg=java.security.MessageDigest.getInstance("MD5"); //or "SHA-1"
if (debug){
System.out.println("摘要前的二進串:"+byte2hex(input));
System.out.println("摘要前的字符串:"+new String(input));
}
alg.update(input);
byte[] digest = alg.digest();
if (debug)
System.out.println("摘要后的二進串:"+byte2hex(digest));
return digest;
}
//字節碼轉換成16進制字符串
public static String byte2hex(byte[] b) {
String hs="";
String stmp="";
for (int n=0;n<b.length;n++){
stmp=(java.lang.Integer.toHexString(b[n] & 0XFF));
if (stmp.length()==1)
hs=hs+"0"+stmp;
else hs=hs+stmp;
if (n<b.length-1)
hs=hs+":";
}
// System.out.println("hs="+hs);
return hs.toUpperCase();
}
public static void main(String[] args) throws Exception{
debug = true;
// byte[] key = getKey();
byte[] key = "好好學習".getBytes();
decode(encode("測試加密".getBytes(),key),key);
// md5("測試加密".getBytes());
md5("A".getBytes());
}
}posted on 2008-04-14 16:14
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