CRC32 output endianness is different between crc32() and hash()
| Bug #45028 | CRC32 output endianness is different between crc32() and hash() | ||||
|---|---|---|---|---|---|
| Submitted: | 2008-05-17 16:03 UTC | Modified: | 2008-08-18 14:33 UTC | ||
| From: | jfrusciante at tiscali dot it | Assigned: | scottmac (profile) | ||
| Status: | Closed | Package: | *Encryption and hash functions | ||
| PHP Version: | 5.2.6 | OS: | * | ||
| Private report: | No | CVE-ID: | None | ||
[2008-05-17 16:03 UTC] 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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[2008-08-18 14:33 UTC] tony2001@php.net