hash_hmac_file
Sometimes a hosting provider doesn't provide access to the Hash extension. Here is a clone of the hash_hmac function you can use in the event you need an HMAC generator and Hash is not available. It's only usable with MD5 and SHA1 encryption algorithms, but its output is identical to the official hash_hmac function (so far at least).
<?php
function custom_hmac($algo, $data, $key, $raw_output = false)
{
$algo = strtolower($algo);
$pack = 'H'.strlen($algo('test'));
$size = 64;
$opad = str_repeat(chr(0x5C), $size);
$ipad = str_repeat(chr(0x36), $size);
if (strlen($key) > $size) {
$key = str_pad(pack($pack, $algo($key)), $size, chr(0x00));
} else {
$key = str_pad($key, $size, chr(0x00));
}
for ($i = 0; $i < strlen($key) - 1; $i++) {
$opad[$i] = $opad[$i] ^ $key[$i];
$ipad[$i] = $ipad[$i] ^ $key[$i];
}
$output = $algo($opad.pack($pack, $algo($ipad.$data)));
return ($raw_output) ? pack($pack, $output) : $output;
}
?>
Example Use:
<?php
custom_hmac('sha1', 'Hello, world!', 'secret', true);
?>
hash_hmac
(PHP 5 >= 5.1.2, PECL hash >= 1.1)
hash_hmac — Generate a keyed hash value using the HMAC method
Beschreibung
string hash_hmac
( string $algo
, string $data
, string $key
[, bool $raw_output = false
] )
Parameter-Liste
- algo
-
Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)
- data
-
Message to be hashed.
- key
-
Shared secret key used for generating the HMAC variant of the message digest.
- raw_output
-
When set to TRUE, outputs raw binary data. Default value (FALSE) outputs lowercase hexits.
Rückgabewerte
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.
Beispiele
Beispiel #1 hash_hmac() example
<?php
echo hash_hmac('ripemd160', 'The quick brown fox jumped over the lazy dog.', 'secret');
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
b8e7ae12510bdfb1812e463a7f086122cf37e4f7
Siehe auch
- hash() - Generate a hash value (message digest)
- hash_init() - Initialize an incremental hashing context
- hash_hmac_file() - Generate a keyed hash value using the HMAC method and the contents of a given file
add a note
User Contributed Noteshash_hmac
KC Cloyd
10-Sep-2009 06:16
10-Sep-2009 06:16
Henry Merriam
04-Aug-2009 05:36
04-Aug-2009 05:36
<?php
/**
* Implementation of the PBKDF2 key derivation function as described in RFC 2898.
*
* PBKDF2 was published as part of PKCS #5 v2.0 by RSA Security. The standard is
* also documented in IETF RFC 2898.
*
* The first four function arguments are as the standard describes:
*
* PBKDF2(P, S, c, dkLen)
*
* The fifth function argument specifies the hash function to be used. This should
* be provided in the same format as used for the hash() function. The default
* hash algorithm is SHA-1, but this is not recommended for new applications.
*
* The function returns false if dk_len is too large. Otherwise it returns the
* derived key as a binary string.
*
* @author Henry Merriam <php@henrymerriam.com>
*
* @param string p password
* @param string s salt
* @param int c iteration count
* @param int dk_len derived key length (octets)
* @param string algo hash algorithm
*
* @return string derived key
*/
function pbkdf2($p, $s, $c, $dk_len, $algo = 'sha1') {
// experimentally determine h_len for the algorithm in question
static $lengths;
if (!isset($lengths[$algo])) { $lengths[$algo] = strlen(hash($algo, null, true)); }
$h_len = $lengths[$algo];
if ($dk_len > (pow(2, 32) - 1) * $h_len) {
return false; // derived key is too long
} else {
$l = ceil($dk_len / $h_len); // number of derived key blocks to compute
$t = null;
for ($i = 1; $i <= $l; $i++) {
$f = $u = hash_hmac($algo, $s . pack('N', $i), $p, true); // first iterate
for ($j = 1; $j < $c; $j++) {
$f ^= ($u = hash_hmac($algo, $u, $p, true)); // xor each iterate
}
$t .= $f; // concatenate blocks of the derived key
}
return substr($t, 0, $dk_len); // return the derived key of correct length
}
}
?>
brent at thebrent dot net
21-May-2009 03:17
21-May-2009 03:17
The hotp algorithms above work with counter values less than 256, but since the counter can be larger, it's necessary to iterate through all the bytes of the counter:
<?php
function oath_hotp ($key, $counter)
{
// Counter
//the counter value can be more than one byte long, so we need to go multiple times
$cur_counter = array(0,0,0,0,0,0,0,0);
for($i=7;$i>=0;$i--)
{
$cur_counter[$i] = pack ('C*', $counter);
$counter = $counter >> 8;
}
$bin_counter = implode($cur_counter);
// Pad to 8 chars
if (strlen ($bin_counter) < 8)
{
$bin_counter = str_repeat (chr(0), 8 - strlen ($bin_counter)) . $bin_counter;
}
// HMAC
$hash = hash_hmac ('sha1', $bin_counter, $key);
return $hash;
}
function oath_truncate($hash, $length = 6)
{
// Convert to dec
foreach(str_split($hash,2) as $hex)
{
$hmac_result[]=hexdec($hex);
}
// Find offset
$offset = $hmac_result[19] & 0xf;
// Algorithm from RFC
return
(
(($hmac_result[$offset+0] & 0x7f) << 24 ) |
(($hmac_result[$offset+1] & 0xff) << 16 ) |
(($hmac_result[$offset+2] & 0xff) << 8 ) |
($hmac_result[$offset+3] & 0xff)
) % pow(10,$length);
}
print "<pre>";
print "Compare results with:";
print " http://tools.ietf.org/html/draft-mraihi-oath-hmac-otp-04\n";
print "Count\tHash\t\t\t\t\t\tPin\n";
for($i=0;$i<=1024;$i=$i+128)
{
print $i."\t".($a=oath_hotp("12345678901234567890",$i));
print "\t".oath_truncate($a)."\n";
}
?>
torben dot egmose at gmail dot com
22-Mar-2009 07:40
22-Mar-2009 07:40
HOTP Algorithm that works according to the RCF http://tools.ietf.org/html/draft-mraihi-oath-hmac-otp-04
The test cases from the RCF document the ASCII string as "123456787901234567890".
But the hex decoded to a string is "12345678901234567890".
Secret="12345678901234567890";
Count:
0 755224
1 287082
<?php
function oath_hotp($key,$counter) {
// Convert to padded binary string
$data = pack ('C*', $counter);
$data = str_pad($data,8,chr(0),STR_PAD_LEFT);
// HMAC
return hash_hmac('sha1',$data,$key);
}
function oath_truncate($hash, $length = 6) {
// Convert to dec
foreach(str_split($hash,2) as $hex) {
$hmac_result[]=hexdec($hex);
}
// Find offset
$offset = $hmac_result[19] & 0xf;
// Algorithm from RFC
return (
(($hmac_result[$offset+0] & 0x7f) << 24 ) |
(($hmac_result[$offset+1] & 0xff) << 16 ) |
(($hmac_result[$offset+2] & 0xff) << 8 ) |
($hmac_result[$offset+3] & 0xff)
) % pow(10,$length);
}
print "<pre>";
print "Compare results with:"
print " http://tools.ietf.org/html/draft-mraihi-oath-hmac-otp-04\n";
print "Count\tHash\t\t\t\t\t\tPin\n";
for($i=0;$i<10;$i++)
print $i."\t".($a=oath_hotp("12345678901234567890",$i))
print "\t".oath_truncate($a)."\n";
Carlos Averett(caverett*@*corecodec,net)
03-Jul-2008 10:54
03-Jul-2008 10:54
Generating OATH-compliant OTP (one time passwords) results in PHP:
<?php
$otp = oath_truncate (oath_hotp ($key, $counter), $length);
function oath_hotp ($key, $counter) {
// Counter
$bin_counter = pack ('C*', $counter);
// Pad to 8 chars
if (strlen ($bin_counter) < 8) {
$bin_counter = str_repeat (chr(0), 8 - strlen ($bin_counter)) . $bin_counter;
}
// HMAC
$hash = hash_hmac ('sha1', $bin_counter, $key);
return $hash;
}
function oath_truncate ($hash, $length = 6) {
// The last byte is used as an offset
$offset = hexdec (substr ($hash, 38)) & 0xf;
// Extract the relevant part, and clear the first bit
$hex_truncated = substr ($hash, $offset * 2, 8);
$bin_truncated = decbin (hexdec ($hex_truncated));
$bin_truncated[0] = '0';
$dec_truncated = bindec ($bin_truncated);
return substr ($dec_truncated, 0 - $length);
}
?>