如何使用特殊算法對字符串進行加密編碼成為另一個字符串?

Question

MD5是不可逆算法，用DES加密然后用BASE64对加密后的二进制数据进行编码http://www.javayou.com

Answer 1

//java.security.MessageDigest alg=java.security.MessageDigest.getInstance("MD5");
      java.security.MessageDigest alga=java.security.MessageDigest.getInstance("SHA-1");
      alga.update(myinfo.getBytes());
      byte[] digesta=alga.digest();      //通过某中方式传给其他人你的信息(myinfo)和摘要(digesta) 对方可以判断是否更改或传输正常
      java.security.MessageDigest algb=java.security.MessageDigest.getInstance("SHA-1");
      algb.update(myinfo.getBytes());
      if (algb.isEqual(digesta,algb.digest())) {
         System.out.println("信息检查正常");
       }
       else
        {
          System.out.println("摘要不相同");
         }

Answer 2

可以考虑http://community.csdn.net/Expert/topic/3270/3270409.xml?temp=.5324671所回复的恺撒算法思想

Answer 3

to:ntzls(三星堆) 謝謝你的代碼，但是為什麼每次 "Hello World"加密後的字符串會不一樣呢，另外卻不能將加密後的字符串重新轉成為 "Hello World"?---------------------------------------------------------------------------
package natoni;import java.util.Random;public class SimpleEncoder {

private static Random random = new Random();

public static void main(String[] args){
String s = "hello world";
System.out.println(s+'\n');
byte[] key = getRandomKey(5);
byte[] s1 = encrypt(key,s.getBytes());
System.out.println(new String(s1)+'\n');
byte[] s2 = decrypt(key,s1);
System.out.println(new String(s2)+'\n');
}

public static byte[] getRandomKey(int length) {
if(length <= 0){
throw new IllegalArgumentException();
}
int rand, index=0;
byte[] result = new byte[length];
for(int i=0; i<(length/5); i++){
rand = random.nextInt();
for(int j=0; j<5; j++) {
result[index++] = (byte)(rand&63);
rand >>= 6;
}
}
rand = random.nextInt();
for(int i=0; i<(length%5); i++) {
result[index++] = (byte)(rand&63);
rand >>= 6;
}
return result;
}

public static byte[] encrypt(byte[] key, byte[] b) {
if(key==null || b==null){
throw new IllegalArgumentException();
}
int index = 0;
byte[] result = (byte[])b.clone();
for(int i=0; i<(b.length/key.length); i++){
for(int j=0; j<key.length; j++){
result[index++] += key[j];
}
}
for(int i=0; i<(b.length%key.length); i++){
result[index++] += key[i]; 
}
return result;
}

public static byte[] decrypt(byte[] key, byte[] b) {
if(key==null || b==null){
throw new IllegalArgumentException();
}
int index = 0;
byte[] result = (byte[])b.clone();
for(int i=0; i<(b.length/key.length); i++){
for(int j=0; j<key.length; j++){
result[index++] -= key[j];
}
}
for(int i=0; i<(b.length%key.length); i++){
result[index++] -= key[i]; 
}
return result;
}
}

Answer 4

这个问题简单，看看加解密api吧

Answer 5

public static javax.crypto.SecretKey genDESKey(byte[] key_byte) throws
        Exception
    {
        SecretKey k = null;
        k = new SecretKeySpec(key_byte, "DESede");
        return k;
    }    public static byte[] desDecrypt(javax.crypto.SecretKey key, byte[] crypt) throws
        Exception
    {
        javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance(
            "DESede");
        cipher.init(javax.crypto.Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(crypt);
    }    public static byte[] desEncrypt(javax.crypto.SecretKey key, byte[] src) throws
        Exception
    {
        javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance(
            "DESede");
        cipher.init(javax.crypto.Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(src);
    }

Answer 6

加密後的字符串會不一樣呢程序中演示的是随机密码。byte[] key = getRandomKey(5);

Answer 7

to: ntzls(三星堆)我是想對加密後的字符串進行解密，這樣就可以得到原來的字符串了

Answer 8

有了加密时的byte[] key 不就可以解密吗？

Answer 9

./    .--...
                                              .-------- 0    .--
                                             /                 .......
                                            '                  ..
                                             '........            ----
                                                      .          --..
                                                       .   .---..   -
                                   分  o               .  '     -.
                                     分               /   '
                                                     / ' ' '
                                   \-分--/....... . '  ' '  '
                                    \ __/ -      - -'  '  ' '
                                                    '  '  ' '
                                     o              '   ' ' '
                                                    '   '  '
                                                     -..'.----------.
                                                        I   ----------
                                                 /////////.