#45028 [Opn->Asn]: CRC32 output endianness is different between crc32() and hash()
ID: 45028
Updated by: tony2001@php.net
Reported By: jfrusciante at tiscali dot it
-Status: Open
+Status: Assigned
Bug Type: *Encryption and hash functions
Operating System: *
PHP Version: 5.2.6
-Assigned To:
+Assigned To: mike
New Comment:
Mike, can you confirm that this patch is correct?
http://dev.daylessday.org/diff/bug45028.diff
Previous Comments:
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[2008-05-17 16:03:25] jfrusciante at tiscali dot it
Description:
------------
When I use dechex() to convert a crc32(), and when I directly use
hash("crc32b", ...), I do not get the same output. In particular, the
endianness of the hash() output seems inverted.
In other words: the output of crc32() seems to be correct in its
integer representation (I compared it with Python implementation), but
converting it to hexadecimal (with dechex() or with any calculator)
produces a hex string inverted in its endianness respect to the output
of hash('crc32b', ...) with the same input.
Reproduce code:
---------------
printf("dechex(crc32(\"AAAAAAAA\")): ".
dechex(crc32("AAAAAAAA")).
"<br><br>");
printf("hash(\"crc32b\",\"AAAAAAAA\"): "
.hash("crc32b", "AAAAAAAA")
."<br>");
Expected result:
----------------
dechex(crc32("AAAAAAAA")): 79b71c0a
hash("crc32b","AAAAAAAA"): 79b71c0a
(or
dechex(crc32("AAAAAAAA")): 0a1cb779
hash("crc32b","AAAAAAAA"): 0a1cb779
I think the first two are the right ones)
Actual result:
--------------
dechex(crc32("AAAAAAAA")): 79b71c0a
hash("crc32b","AAAAAAAA"): 0a1cb779
Please note that the difference is only in the bytes order.
"0a-1c-b7-79" is like "79-b7-1c-0a" with inverted endianness, while both
lines should output the same values despite different architectures.
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