(PHP 4, PHP 5)
mhash — Computes hash
$hash
, string $data
[, string $key
] )
mhash() applies a hash function specified by
hash to the data.
hash
The hash ID. One of the MHASH_hashname constants.
data
The user input, as a string.
key
If specified, the function will return the resulting HMAC instead. HMAC is keyed hashing for message authentication, or simply a message digest that depends on the specified key. Not all algorithms supported in mhash can be used in HMAC mode.
Returns the resulting hash (also called digest) or HMAC as a string, or
FALSE on error.
holdoffhunger at gmail dot com (2012-06-29 11:52:34)
The MHash function here lists one disclaimer at the top when providing a key to the mhash function : "Not all algorithms supported in mhash can be used in HMAC mode." So, what algorithms blow up and what do fine when it comes to doing keyed, HMAC hashing? The destructive ones are: Adler32, CRC32, CRC32B, and GOST. These are the first four, predefined constants listed with the MHash Application Package: http://www.php.net/manual/en/mhash.constants.php . Providing one of these algorithms with an HMAC key (of string-length greater than one) creates the following error message: "Warning: mhash() [function.mhash]: mhash initialization failed in [(folder-location)] on line 181". If you really want to use these algorithms in creating your HMAC hashes, the function Hash_hmac() from the HASH-Message Digest Framework package is capable of doing that perfectly.
Again, that is if the string length is greater than one. Why string length greater than one? Well, if the key value is blank, it is ignored as a parameter altogether. So, if you feed the mhash function an algorithm that is not compatible with HMAC hashing and an HMAC key that's blank (""), it will work the same as if it had received no HMAC key at all. This is different from the way the Hash_hmac() function of the HASH-MDF works. In the case of the Hash_hmac() function, feeding a blank HMAC key will use that blank key in generating the HMAC hash. Even with functions that can do HMAC hashing, like MD5 or SHA1, if the MHash() is given a blank HMAC key, it will ignore the key and just return the results of standard, non-HMAC hashing. It's probably not wise to use a blank HMAC key anyway, but it's good to know that the hashing algorithm changes altogether if the provided HMAC key is blank.
Some sample code to demonstrate :
<?php
// Author: holdoffhunger@gmail.com
// Preset Data
// ---------------------------------------------------
$string_to_hash = "The hash_hmac() function better to use for these purposes.";
$blank_hmac_key = "";
// MHash - Hashing With and Without HMAC Parameter
// ---------------------------------------------------
$mhash_result_with_hmac_parameter = bin2hex(mhash(MHASH_CRC32, $string_to_hash, $blank_hmac_key));
$mhash_result_without_hmac_parameter = bin2hex(mhash(MHASH_CRC32, $string_to_hash));
// MHash - Hashing With and Without HMAC Parameter
// ---------------------------------------------------
$hash_result_with_hmac_parameter = hash_hmac("crc32", $string_to_hash, $blank_hmac_key);
$hash_result_without_hmac_parameter = hash("crc32", $string_to_hash);
// Print Results
// ---------------------------------------------------
print("MHASH (CRC32 Algorithm) With Blank HMAC Key: $mhash_result_with_hmac_parameter .<br>");
print("MHASH (CRC32 Algorithm) Without HMAC Processing: $mhash_result_without_hmac_parameter .<br><br>");
print("HASH (CRC32 Algorithm) With Blank HMAC Key: $hash_result_with_hmac_parameter .<br>");
print("HASH (CRC32 Algorithm) Without HMAC Processing: $hash_result_without_hmac_parameter .");
?>
Results :
...................................
MHASH (CRC32 Algorithm) With Blank HMAC Key: f665c094 .
MHASH (CRC32 Algorithm) Without HMAC Processing: f665c094 .
HASH (CRC32 Algorithm) With Blank HMAC Key: 3041f4f8 .
HASH (CRC32 Algorithm) Without HMAC Processing: f665c094 .
holdoffhunger at gmail dot com (2012-06-27 19:27:15)
Both cryptography packages, the MHash and the HASH Message Digest Framework, have the same algorithms, and yet, they both sometimes to produce wildly different results from each other when applying the same algorithm to the same piece of data. The SHA-x algorithms, as designed by the NSA, all seem to have concrete standards for producing their hash values, so they have similar results. Even the two MD5 implementations produce identical results, and the same goes for Gost, RipeMD, CRC32, Whirlpool, Snefru256 (known as 'Snefru256' in MHash and simply 'Snefru' in HASH-MDF), and Tiger (the three-round versions in HASH-MDF to simply 'Tigerx' in MHash).
However, the algorithms CRC32B and Adler32 each produce different results when called from either MHash or HASH-MDF, possibly because they are hashing algorithms designed to be checksums rather than something that can produce a string as a unique identifier for a particular piece of information. For that reason, if you ever publish the hash results with the data you're putting out publicly, it's probably wise to indicate whether it's the MHash or HASH-MDF implementation of the algorithm. Otherwise, the hash value won't provide much use as a unique identifier for the particular piece of data or for the file.
Some example code to better explain what I mean :
<?php
// Author: holdoffhunger@gmail.com
// SHA-1 Hashing
// ---------------------------------------------------
$mhash_sha1_results = bin2hex(mhash(MHASH_SHA1, "secret"));
$hash_mdf_sha1_results = hash("sha1", "secret", FALSE);
print("MHash SHA-1: $mhash_sha1_results .<br>");
print("HASH-MDF SHA-1: $hash_mdf_sha1_results .<br><br>");
// Whirlpool Hashing
// ---------------------------------------------------
$mhash_whirlpool_results = bin2hex(mhash(MHASH_WHIRLPOOL, "secret"));
$hash_mdf_whirlpool_results = hash("whirlpool", "secret", FALSE);
print("MHash Whirlpool: $mhash_whirlpool_results .<br>");
print("HASH-MDF Whirlpool: $hash_mdf_whirlpool_results .<br><br>");
// CRC32B Hashing
// ---------------------------------------------------
$mhash_crc32b_results = bin2hex(mhash(MHASH_CRC32B, "secret"));
$hash_mdf_crc32b_results = hash("crc32b", "secret", FALSE);
print("MHash CRC32B: $mhash_crc32b_results .<br>");
print("HASH-MDF CRC32B: $hash_mdf_crc32b_results .<br><br>");
// Adler32 Hashing
// ---------------------------------------------------
$mhash_adler32_results = bin2hex(mhash(MHASH_ADLER32, "secret"));
$hash_mdf_adler32_results = hash("adler32", "secret", FALSE);
print("MHash Adler32: $mhash_adler32_results .<br>");
print("HASH-MDF Adler32: $hash_mdf_adler32_results .<br><br>");
?>
Expected Results :
........................
MHash SHA-1: e5e9fa1ba31ecd1ae84f75caaa474f3a663f05f4 .
HASH-MDF SHA-1: e5e9fa1ba31ecd1ae84f75caaa474f3a663f05f4 .
MHash Whirlpool: e061b87a674ae3880e159ab55ed35d
6c5e8a6aefac6ab08304a50588018d
377b28639bb15fdeedf006d57e45f7
b4298e6dfefceaf7c92c826a708fe6d
1156eb3 .
HASH-MDF Whirlpool: e061b87a674ae3880e159ab55ed35d
6c5e8a6aefac6ab08304a50588018d
377b28639bb15fdeedf006d57e45f7
b4298e6dfefceaf7c92c826a708fe6d
1156eb3 .
MHash CRC32B: e5e8a25c .
HASH-MDF CRC32B: 5ca2e8e5 .
MHash Adler32: 8702d108 .
HASH-MDF Adler32: 08d10287 .
hm2k at php dot net (2009-01-20 07:16:22)
mhash support now appears in the Pear PHP_Compat package, for support without building PHP with mhash.
numien(at)deathwyrm(dot)com (2007-01-31 05:21:22)
---Quote---
pack("H*", md5($str)) == mhash(MHASH_MD5, $str)
pack("H*", sha1($str)) == mhash(MHASH_SHA1, $str)
---/Quote---
That's an awfully inefficient way of doing things. You can just put ", true" after md5 or sha1 to get binary output instead of having it convert it to hex then back.
Easier way:
md5($str, true) == mhash(MHASH_MD5, $str)
sha1($str, true) == mhash(MHASH_SHA1, $str)
marcel446 at yahoo dot com (2005-06-06 04:15:54)
Just in case you did not observe, the function of Lance is independent of hash fuction used to get HMAC , so if one use sha1() function from php instead md5() will get sha1 HMAC.
Just try .
Thanks again Lance
robbie [at] averill [dot] co [dot] nz (2005-03-18 17:17:58)
This confused me a bit when I first read the documetation for mhash. The functions that accept a hash accept them as an INTEGER not a STRING. In this case, MHASH_MD5 = 1. It is a constant, not a string.
Just thought I'd point that out, so if anyone is confused they can read that. That's the use of mhash_get_hash_name(). You input the constant (which is an integer) and it returns the hash name.
fernan at ispwest dot com (2004-11-02 00:03:45)
Thanks a lot to Lance for showing how to create mhash without installing the perl extension for mhash.
I have been asking my webhosting administrator to recompile Perl with mhash extension, but do not want to do it. As a result, our company can't get credit card authorization because they require fingerprint which uses the function mhash. Now, it's working fine.
Thanks a lot, Lance.....
Fernan
jerry d0t wilborn at fast d0t net (2004-07-02 09:36:14)
in responce to lance's post:
the function comes back with a hex representation of the hmac, if you wish to convert to what mhash returns natively (binary) use: pack("H*", hmac(variables...));
lance_rushing at hot* spamfree *mail dot com (2003-07-09 17:02:20)
Don't forget php has two built in hashing algorithms:
md5(), and sha1()
So if you are using: mhash(MHASH_MD5, $str) or mhash(MHASH_SHA1, $str) you could use md5($str) or sha1($str).
** But remember that md5() and sha1() produce HEX output while mhash() produces a BIN output. So:
md5($str) == bin2hex(mhash(MHASH_MD5, $str))
sha1($str) == bin2hex(mhash(MHASH_SHA1, $str))
AND
pack("H*", md5($str)) == mhash(MHASH_MD5, $str)
pack("H*", sha1($str)) == mhash(MHASH_SHA1, $str)
(Just remember to pack() or bin2hex() your output to get the output you need)
-Lance
lance_rushing at hot* spamfree *mail dot com (2002-11-27 20:36:25)
Want to Create a md5 HMAC, but don't have hmash installed?
Use this:
function hmac ($key, $data)
{
// RFC 2104 HMAC implementation for php.
// Creates an md5 HMAC.
// Eliminates the need to install mhash to compute a HMAC
// Hacked by Lance Rushing
$b = 64; // byte length for md5
if (strlen($key) > $b) {
$key = pack("H*",md5($key));
}
$key = str_pad($key, $b, chr(0x00));
$ipad = str_pad('', $b, chr(0x36));
$opad = str_pad('', $b, chr(0x5c));
$k_ipad = $key ^ $ipad ;
$k_opad = $key ^ $opad;
return md5($k_opad . pack("H*",md5($k_ipad . $data)));
}
-----
To test:
Run this on a server _with_ mhash installed:
$key = 'Jefe';
$data = "what do ya want for nothing?";
echo hmac($key, $data);
echo "<br>\n";
echo bin2hex (mhash(MHASH_MD5, $data, $key));
should produce:
750c783e6ab0b503eaa86e310a5db738
750c783e6ab0b503eaa86e310a5db738
Happy hashing.
shimon_d at hotmail dot com (2002-08-22 12:05:38)
password security:
when you hash passwords to save them in cookie , url ,etc' my sugsession is to hash them with date
becouse of evry body can view server log or any other loged info and reuse the hash
ie.: to re call a url eg. admin.php?user=root&passhash=5rft346tert
in this example the password keepped in secret but what stopping me to reuse the url
hash("secret") // bad security
hash("secret".date("Ymg")) // better security
// the hash good only for today
luc at 2113 dot ch (2001-12-28 05:42:45)
Netscape messaging / directory server 4+ uses SHA-1
to store password in the ldap database (slapd).
The password is first SHA-1 hashed then base64 encoded:
$pwd = "secret";
$hash = "{SHA}".base64_encode( mHash(MHASH_SHA1, $pwd));
echo "Hash: ". $hash ;
paulj at 5emedia dot net (2001-12-06 10:02:23)
Many digest algorithms (especially MD5) are less secure if you are hashing data that is smaller than the algorithm's output. I recommend either hashing a secret key/salt with the original data to increase it's security.
(2001-05-02 13:02:27)
Using RedHat 7.1, after compile/install, I had to add the line
/usr/local/lib
to /etc/ld.so.conf and run ldconfig to make this work.