Jive 2.5 SkinUtils.java 中的 encodePasswordCookie decodePasswordCookie

package code;

public class T3 {
	private final static int  ENCODE_XORMASK = 0x5A; // 十六进制 90
    private final static char ENCODE_DELIMETER = '\002'; // \转义字符 stx
    private final static char ENCODE_CHAR_OFFSET1 = 'A';
    private final static char ENCODE_CHAR_OFFSET2 = 'h';
	public static void main(String[] args) {
		System.out.println(T3.encodePasswordCookie("chen", "chen"));
		System.out.println(T3.decodePasswordCookie("JkDkJkDkMmMkIhEhMh"));
	}
	
    private static String encodePasswordCookie(String username, String password)
    {
        StringBuffer buf = new StringBuffer();
        if (username != null && password != null) {
            byte[] bytes = (username + ENCODE_DELIMETER + password).getBytes(); //String.getBytes()使用给定的 charset 将此 String 
                                                                                           //编码到 byte 序列，并将结果存储到新的 byte 数组对象
            int b;

            for (int n = 0; n < bytes.length; n++) {
                b = bytes[n] ^ (ENCODE_XORMASK + n);  // ^ 表示异或
                buf.append((char)(ENCODE_CHAR_OFFSET1 + (b & 0x0F))); //& 与
                buf.append((char)(ENCODE_CHAR_OFFSET2 + ((b >> 4) & 0x0F))); //>>右移
            }
        }
        return buf.toString();
    }

    private static String[] decodePasswordCookie( String cookieVal ) {

        // check that the cookie value isn't null or zero-length
        if( cookieVal == null || cookieVal.length() <= 0 ) {
            return null;
        }

        // unrafel the cookie value
        char[] chars = cookieVal.toCharArray();
        byte[] bytes = new byte[chars.length / 2];
        int b;
        for (int n = 0, m = 0; n < bytes.length; n++) {
            b = chars[m++] - ENCODE_CHAR_OFFSET1;
                                        //m开始为0

           b |= (chars[m++] - ENCODE_CHAR_OFFSET2) << 4;
                                        //m开始为1

           bytes[n] = (byte)(b ^ (ENCODE_XORMASK + n));
        }
        cookieVal = new String(bytes);
        int	pos = cookieVal.indexOf(ENCODE_DELIMETER);
        String username = (pos < 0) ? "" : cookieVal.substring(0, pos);
        String password = (pos < 0) ? "" : cookieVal.substring(pos + 1);
         
         //添加一个输出测试
        System.out.println("用户名:"+username+"\n"+"密码:"+password);
        return new String[] {username, password};
    }

}

 

结果：

JkDkJkDkMmMkIhEhMh
用户名:chen
密码:chen

 

用表格分析encode

字符	ASCII	ENCODE_XORMASK+n	二^三列的运算结果(异或)
c	1100011	1011010     n=0	111001
h	1101000	1011011     n=1	110011
e	1100101	1011100	111001
n	1101110	1011101	110011
\002 stx	0000010	1011110	1011100
c	1100011	1011111	111100
h	1101000	1100000	1000
e	1100101	1100001	100
n	1101110	1100010	1100

 

 b = bytes[n] ^ (ENCODE_XORMASK + n);   //上表的第四列结果

//第一个append的是  b的低4位 +'A' =X
 buf.append((char)(ENCODE_CHAR_OFFSET1 + (b & 0x0F))); //& 与

 //第二个append的是 b的高4为 +'h' =Y
 buf.append((char)(ENCODE_CHAR_OFFSET2 + ((b >> 4) & 0x0F))); //>>右移

 

 decode译码过程(X-'A')|[(Y-'h')<<4] 最终再一个异或