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Java MD5 doesn't match php?

Posted on 2003-12-03
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1,386 Views
Last Modified: 2008-02-26
Java:
------------------------------------------------------
StringBuffer sb = new StringBuffer();

        try {
            String data = "apple";
            MessageDigest messageDigest = MessageDigest.getInstance("MD5");
            messageDigest.update(data.getBytes());
            byte[] digestBytes = messageDigest.digest();

            /* convert to hexstring */
            String hex = null;

            for (int i = 0; i < digestBytes.length; i++) {
                hex = Integer.toHexString(0xFF & digestBytes[i]);

                if (hex.length() < 2) {
                    sb.append("0");
                    sb.append(hex);
                }
                sb.append(hex);
            }
        }
        catch (Exception ex) {
            System.out.println(ex.getMessage());
        }

        System.out.println(sb.toString());

PHP:
------------------------------------------------------
echo md5("apple");
or http://tw.php.net/md5

--
I got a
1f3870be274f6c49b3e31a0cc6728957f (from Java)
1f3870be274f6c49b3e31a0c6728957f  (from PHP)

always differ one bit.

Thanks in advance:)
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Question by:YuRen
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7 Comments
 
LVL 15

Accepted Solution

by:
jimmack earned 50 total points
ID: 9873072
               if (hex.length() < 2) {
                    sb.append("0");
                    sb.append(hex);
                }
                sb.append(hex);

should be:

                if (hex.length() < 2) {
                    sb.append("0");
                }
                sb.append(hex);

You were appending "hex" twice if you found a value less than 0x10 ;-)
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Author Comment

by:YuRen
ID: 9873190
You save my life, jimmack
:)

A few days later, I would implement the security scheme in my web site.
http://www.uwan.com.tw/   Enjoy it!
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Expert Comment

by:jimmack
ID: 9874566
;-)
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Expert Comment

by:kelvinlaw
ID: 10359519
may i ask :

hex = Integer.toHexString(0xFF & digestBytes[i]);

why 0xFF is needed?
0xFF should be 11111111

0xFF & digestBytes[i] same as  digestBytes[i] ??

thanks
0
 

Author Comment

by:YuRen
ID: 10363555
0xff shoud be 00000000 00000000 00000000 11111111

--
        byte[] digestBytes = { (byte) 0x7f, (byte) 0x8f, (byte) 0xff };

        for (int i = 0; i < digestBytes.length; i++) {
            System.out.print(Integer.toHexString(digestBytes[i]) + "\t");
            System.out.print(Integer.toHexString(0xff & digestBytes[i]) + "\t");
        }
--
result:
7f      7f      ffffff8f      8f      ffffffff      ff      
0
 

Expert Comment

by:kelvinlaw
ID: 10364544
1 byte is 8 bits, right?
but
System.out.print(Integer.toBinaryString(digestBytes[i])

if give me a 32 bits answer if digestBytes[i] >= 0x80....


WHY????
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Author Comment

by:YuRen
ID: 10368345
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