hash_copy
The 'octets reversed' you are seeing is the bug 45028 which has been fixed. http://bugs.php.net/bug.php?id=45028
The difference between crc32 and crc32b is explained on mhash man page. crc32 is the one used on ethernet, while crc32b is the one used on zip, png... They differ on the table used.
hash_file
(PHP 5 >= 5.1.2, PECL hash:1.1-1.5)
hash_file — Generate a hash value using the contents of a given file
Description
string hash_file
( string $algo
, string $filename
[, bool $raw_output
] )
Parameters
- algo
-
Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)
- filename
-
URL describing location of file to be hashed; Supports fopen wrappers.
- raw_output
-
When set to TRUE, outputs raw binary data. Default value (FALSE) outputs lowercase hexits.
Return Values
Returns a string containing the calculated message digest as lowercase hexits unless raw_output is set to true in which case the raw binary representation of the message digest is returned.
Examples
Example #1 Using hash_file()
<?php
/* Create a file to calculate hash of */
file_put_contents('example.txt', 'The quick brown fox jumped over the lazy dog.');
echo hash_file('md5', 'example.txt');
?>
The above example will output:
5c6ffbdd40d9556b73a21e63c3e0e904
add a note
User Contributed Noteshash_file
Keisial at gmail dot com
11-Sep-2008 07:46
11-Sep-2008 07:46
allaryin at gmail dot com
23-Jul-2008 11:16
23-Jul-2008 11:16
For those who are wondering, there appears to be no fundamental difference between hash_file('md5')/hash_file('sha1') and md5_file()/sha1_file(). They produce identical output and have comparable performance.
There is, however, a difference between hash_file('crc32') and something silly like crc32(file_get_contents()).
crc32(file_get_contents())'s results are most similar to those of hash_file('crc32b'), just with the octets reversed:
<?php
$fname = "something.png";
$hash = hash_file( 'crc32', $fname );
echo "crc32 = $hash\n";
$hash = hash_file( 'crc32b', $fname );
echo "crc32b = $hash\n";
$hash = sprintf("%x",crc32(file_get_contents($fname)));
echo "manual = $hash\n";
?>
crc32 = f41d7f4e
crc32b = 7dafbba4
manual = a4bbaf7d