MD5加密和二次加密的方法

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import java.security.MessageDigest;

public class MD5andKL {
// MD5加码。32位
public static String MD5(String inStr) {
MessageDigest md5 = null;
try {
   md5 = MessageDigest.getInstance("MD5");
} catch (Exception e) {
   System.out.println(e.toString());
   e.printStackTrace();
   return "";
}
char[] charArray = inStr.toCharArray();
byte[] byteArray = new byte[charArray.length];

for (int i = 0; i < charArray.length; i++)
   byteArray[i] = (byte) charArray[i];

byte[] md5Bytes = md5.digest(byteArray);

StringBuffer hexValue = new StringBuffer();

for (int i = 0; i < md5Bytes.length; i++) {
   int val = ((int) md5Bytes[i]) & 0xff;
   if (val < 16)
    hexValue.append("0");
   hexValue.append(Integer.toHexString(val));
}

return hexValue.toString();
}

// 可逆的加密算法
public static String KL(String inStr) {
// String s = new String(inStr);
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
   a[i] = (char) (a[i] ^ 'a');    //a是加密的密钥,可变
}
String s = new String(a);
return s;
}

// 加密后解密
public static String JM(String inStr) {
char[] a = inStr.toCharArray();
for (int i = 0; i < a.length; i++) {
   a[i] = (char) (a[i] ^ 'a');     //a解密的密钥,与加密相同即可
}
String k = new String(a);
return k;
}

//测试
public static void main(String args[]) {
String s = new String("a");
System.out.println("原始：" + s);
System.out.println("MD5后：" + MD5(s));
System.out.println("MD5后再加密：" + KL(MD5(s)));
System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
}

}

测试结果：

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