Hash 函数
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PHP手册

hash

(PHP 5 >= 5.1.2, PECL hash >= 1.1)

hash — Generate a hash value (message digest)

说明

string hash ( string $algo , string $data [, bool $raw_output = false ] )

参数

algo

Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..)

data

Message to be hashed.

raw_output

When set to TRUE, outputs raw binary data. FALSE outputs lowercase hexits.

返回值

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.

更新日志

版本 说明
5.4.0 The tiger algorithm now uses big-endian byte ordering.

范例

Example #1 A hash() example

<?php
echo hash('ripemd160', 'The quick brown fox jumped over the lazy dog.');
?>

以上例程会输出：

ec457d0a974c48d5685a7efa03d137dc8bbde7e3

参见

Hash 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Generate a hash value (message digest)

用户评论:

sneskid at hotmail dot com (15-Mar-2012 10:41)

syntax error: extra ")" in second example line 2

sneskid at hotmail dot com (15-Mar-2012 05:32)

On two different servers I found that crc32() relates to hash('crc32b',)
This may be good to know if you are writing a crc32_file function based on hash_file.
(The example does not compensate for negative crc32 results)
<?php
$val = 'hello';
var_dump(crc32($val) == ( '0x' . hash('crc32b', $val) ) ); // bool(true)
var_dump(crc32($val) == ( '0x' . hash('crc32', $val) ) ); // bool(false)
?>

Also if you are looking for a way to reduce collisions and still keep the hash result small (smaller than say md5) you could get a nice database friendly 64 bit value by using hash/crc32 and hash/crc32b, which is slower than a single md5 but the result may be more suitable for certain tasks.
<?php
$val = 'hello';
$crc64 = ( '0x' . hash('crc32', $val) . hash('crc32b', $val) ) );
var_dump($crc64); // string(18) "0x3d6531193610a686"
var_dump($crc64 + 0); // int(4423996193312384646)
?>

(examples tested on php 5.2.17)
note: ('0x' . $hex . + 0) is faster than base_convert($hex,16,10)

nmmm at nmmm dot nu (20-Jul-2011 09:50)

I was interested how "long" each hash is, so I did:

<?php
$data = "hello";

foreach (hash_algos() as $v) {
        $r = hash($v, $data, false);
        printf("%-12s %3d %s\n", $v, strlen($r), $r);
}
?>

which produce (long hashes are cropped)

md2           32 a9046c73e00331af68917d3804f70655                  
md4           32 866437cb7a794bce2b727acc0362ee27
md5           32 5d41402abc4b2a76b9719d911017c592
sha1          40 aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d
sha256        64 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e730
sha384        96 59e1748777448c69de6b800d7a33bbfb9ff1b463e44354c3553
sha512       128 9b71d224bd62f3785d96d46ad3ea3d73319bfbc2890caadae2d
ripemd128     32 789d569f08ed7055e94b4289a4195012
ripemd160     40 108f07b8382412612c048d07d13f814118445acd
ripemd256     64 cc1d2594aece0a064b7aed75a57283d9490fd5705ed3d66bf9a
ripemd320     80 eb0cf45114c56a8421fbcb33430fa22e0cd607560a88bbe14ce
whirlpool    128 0a25f55d7308eca6b9567a7ed3bd1b46327f0f1ffdc804dd8bb
tiger128,3    32 a78862336f7ffd2c8a3874f89b1b74f2
tiger160,3    40 a78862336f7ffd2c8a3874f89b1b74f2f27bdbca
tiger192,3    48 a78862336f7ffd2c8a3874f89b1b74f2f27bdbca39660254
tiger128,4    32 1c2a939f230ee5e828f5d0eae5947135
tiger160,4    40 1c2a939f230ee5e828f5d0eae5947135741cd0ae
tiger192,4    48 1c2a939f230ee5e828f5d0eae5947135741cd0aefeeb2adc
snefru        64 7c5f22b1a92d9470efea37ec6ed00b2357a4ce3c41aa6e28e3b
gost          64 a7eb5d08ddf2363f1ea0317a803fcef81d33863c8b2f9f6d7d1
adler32        8 062c0215
crc32          8 3d653119
crc32b         8 3610a686
haval128,3    32 85c3e4fac0ba4d85519978fdc3d1d9be
haval160,3    40 0e53b29ad41cea507a343cdd8b62106864f6b3fe
haval192,3    48 bfaf81218bbb8ee51b600f5088c4b8601558ff56e2de1c4f
haval224,3    56 92d0e3354be5d525616f217660e0f860b5d472a9cb99d6766be
haval256,3    64 26718e4fb05595cb8703a672a8ae91eea071cac5e7426173d4c
haval128,4    32 fe10754e0b31d69d4ece9c7a46e044e5
haval160,4    40 b9afd44b015f8afce44e4e02d8b908ed857afbd1
haval192,4    48 ae73833a09e84691d0214f360ee5027396f12599e3618118
haval224,4    56 e1ad67dc7a5901496b15dab92c2715de4b120af2baf661ecd92
haval256,4    64 2d39577df3a6a63168826b2a10f07a65a676f5776a0772e0a87
haval128,5    32 d20e920d5be9d9d34855accb501d1987
haval160,5    40 dac5e2024bfea142e53d1422b90c9ee2c8187cc6
haval192,5    48 bbb99b1e989ec3174019b20792fd92dd67175c2ff6ce5965
haval224,5    56 aa6551d75e33a9c5cd4141e9a068b1fc7b6d847f85c3ab16295
haval256,5    64 348298791817d5088a6de6c1b6364756d404a50bd64e645035f

tyler11440_rs2 at hotmail dot com (06-Jul-2011 02:46)

Another method. Not something you would want to use for utmost security, however it gets the job done.

<?php
function THashAndCrypt($input)
{
return str_rot13(base64_encode(hash('sha512', $input)));
}

function TdeCrypt($input)
{
return str_rot13(base64_decode($input));
}
?>

This function takes your password, uses the rot13 method to jumble the text. Then it encodes it into a long jumbled base64 string. Finally, it is encrypted with SHA512.

Not only does this use a secure SHA method, but it makes it generally more difficult to even determine which hash method was used. BY NO MEANS am i a professional PHP coder, but throughout my career i have done things like this to make things harder to decrypt in the event that they are stolen/compromised. Be aware that, simply by posting this on the net, i have made it less secure. When you want security, ALWAYS MAKE YOUR OWN FUNCTIONS.

From my understanding, you should always use salt for added security. Salt can be added to these functions with little effort. Using salt in conjunction with several hundred unique hashing/encoding passes can make your passwords nearly uncrackable. Rather than taking an hour to find, the hacker is forced to either give up or wait an extra 2 years to successfully crack your encoded strings.

shimyshack at gmail dot com (21-Jan-2011 06:13)

This is a small function I created to generate a unique ID using sha512 encryption.

If $id is NULL, the generated string will be random. If not, the same hash will always be presented, provided the $salt is the same.

$length is the length of the generated string. If NULL, the default 128 characters is used.

<?php
function gen_unique_id($id = NULL, $salt = NULL, $length = NULL){
    $id = ($id == NULL) ? uniqid(hash("sha512",rand()), TRUE) : $id;
    $code = hash("sha512", $id.$salt);
    return $length == NULL ? $code : substr($code, 0, $length);
}
?>

rojaro at gmail dot com (15-Sep-2010 04:01)

If the given algo parameter contains an algorithm that is not supported, the hash function will return bool(false) and issue a warning.

robert+nospam at robert-gonzalez dot com (18-Jan-2010 12:08)

I've recently had the need to look at various hash algorithms and their values of the same string. To make my life a little easier I wrote this little script. It takes a string and runs it through all of the available hash algorithms on your server, outputting them in a clean little HTML table.

-----

<?php
/* Get the posted value of the form if there is one */
$p = empty($_POST['p']) ? null : $_POST['p'];
?>
<html>
<head><title>Hash testing</title></head>
<style type="text/css">
    table {border-collapse: collapse;}
    table, td, th {border: solid 1px #ccc;}
    th {background: #e1e1e1;border-color: #999;}
    td, th {padding: 0.25em;}
    td.algo {font-weight: bold;}
    tr.on td {background: #f0f0f0;}
</style>
<body>
    <h1>String hashing</h1>
    <form method="post" action="<?php echo basename(__FILE__) ?>">
        <p><label for="p">Enter a string to hash:</label><br /><input id="p" type="text" name="p" value="<?php echo $p ?>" /></p>
        <p><input type="submit" name="submit" value="Hash It" /></p>
    </form>
   
    <?php /* If there is a posted value use it */ ?>
    <?php if ($p): ?>
    <hr />
    <h2>Table of hash values for <em><?php echo $p ?></em> based on algorithm</h2>
    <table>
        <tr>
            <th>Algorithm</th>
            <th>Hashed value of <em><?php echo $p ?></em></th>
        </tr>
        <?php /* Loop through each hash algorithm, colorizing every other row */ ?>
        <?php $on = false; foreach (hash_algos() as $algo): ?>
        <tr<?php if ($on): ?> class="on"<?php endif; ?>>
            <td class="algo"><?php echo $algo ?></td>
            <td class="hash"><?php echo hash($algo, $p) ?></td>
        </tr>
    <?php $on = !$on; endforeach; ?>
    </table>
    <?php endif; ?>
</body>
</html>

Kai Petzke (16-Oct-2009 01:14)

The well known hash functions MD5 and SHA1 should be avoided in new applications. Collission attacks against MD5 are well documented in the cryptographics literature and have already been demonstrated in practice. Therefore, MD5 is no longer secure for certain applications.

Collission attacks against SHA1 have also been published, though they still require computing power, which is somewhat out of scope. As computing power increases with time and the attacks are likely to get better, too, attacks against systems relying on SHA1 for security are likely to become feasible within the next few years.

There is no lack of potential alternative hash algorithms, as the many choices for the "algo" argument of PHPs hash() function already suggests. Unfortunately, there is lack of analysis, as to how secure these alternative algorithms are. It is rather safe to assume, though, that the SHA2 family with its most prominent members SHA-256 und SHA-512, is better than SHA1.

When storing password hashes, it is a good idea to prefix a salt to the password before hashing, to avoid the same passwords to hash to the same values and to avoid the use of rainbow tables for password recovery. Unlike suggested in other articles, there is no security advantage in putting the salt in the middle, or even at both the beginning and the end, of the combined salt-password-string.

Rather, there are two other factors, that determine the strength of the salt: Its length and its variability. For example, using the same salt for all passwords is easy to implement, but gives only very little additional security. In particular, if users type the same passwords, they will still hash to the same value!

Therefore, the salt should be random string with at least as many variable bits, as there are bits in the hash result. In the user database, store username, the randomly generated salt for that user, and the result of hashing the salt-password-string. Access authentication is then done by looking up the entry for the user, calculating the hash of the salt found in the database and the password provided by the user, and comparing the result with the one stored in the database.

luka8088 at gmail dot com (14-Mar-2009 11:20)

Performance test results on my laptop:
Results are here shorten to fit php web notes ...
This was tested with 1024000 bytes (1000 KB) of random data, md4 always gets the first place, and md2 always get the last place :)

Results: (in microseconds)
   1.  md4                           5307.912
   2.  md5                           6890.058
   3.  crc32b                        7298.946
   4.  crc32                         7561.922
   5.  sha1                          8886.098
   6.  tiger128,3                    11054.992
   7.  haval192,3                    11132.955
   8.  haval224,3                    11160.135
   9.  tiger160,3                    11162.996
  10.  haval160,3                    11242.151
  11.  haval256,3                    11327.981
  12.  tiger192,3                    11630.058
  13.  haval128,3                    11880.874
  14.  tiger192,4                    14776.945
  15.  tiger128,4                    14871.12
  16.  tiger160,4                    14946.937
  17.  haval160,4                    15661.954
  18.  haval192,4                    15717.029
  19.  haval256,4                    15759.944
  20.  adler32                       15796.184
  21.  haval128,4                    15887.022
  22.  haval224,4                    16047.954
  23.  ripemd256                     16245.126
  24.  haval160,5                    17818.927
  25.  haval128,5                    17887.115
  26.  haval224,5                    18085.002
  27.  haval192,5                    18135.07
  28.  haval256,5                    18678.903
  29.  sha256                        19020.08
  30.  ripemd128                     20671.844
  31.  ripemd160                     21853.923
  32.  ripemd320                     22425.889
  33.  sha384                        45102.119
  34.  sha512                        45655.965
  35.  gost                          57237.148
  36.  whirlpool                     64682.96
  37.  snefru                        80352.783
  38.  md2                           705397.844

Code for generating this:
(compatible both with browser and cli mode)

<pre>

<?php

echo 'Building random data ...' . PHP_EOL;
@ob_flush();flush();

$data = '';
for ($i = 0; $i < 64000; $i++)
    $data .= hash('md5', rand(), true);

echo strlen($data) . ' bytes of random data built !' . PHP_EOL . PHP_EOL . 'Testing hash algorithms ...' . PHP_EOL;
@ob_flush();flush();

$results = array();
foreach (hash_algos() as $v) {
    echo $v . PHP_EOL;
    @ob_flush();flush();
    $time = microtime(true);
    hash($v, $data, false);
    $time = microtime(true) - $time;
    $results[$time * 1000000000][] = "$v (hex)";
    $time = microtime(true);
    hash($v, $data, true);
    $time = microtime(true) - $time;
    $results[$time * 1000000000][] = "$v (raw)";
}

ksort($results);

echo PHP_EOL . PHP_EOL . 'Results: ' . PHP_EOL;

$i = 1;
foreach ($results as $k => $v)
    foreach ($v as $k1 => $v1)
        echo ' ' . str_pad($i++ . '.', 4, ' ', STR_PAD_LEFT) . '  ' . str_pad($v1, 30, ' ') . ($k / 1000) . ' microseconds' . PHP_EOL;

?>

</pre>

kevin at bionichippo dot com (14-Mar-2009 08:06)

When using hash() for storing passwords, I've found that the best practice is not to use just one salt, but two. This example uses my preferred algorithm for passwords, whirlpool.

This way, even if someone can produce a rainbow table for your algorithm, and has the salt to do it with, they will never know where in the hash parameter the second salt was placed, because they don't know the length of the actual password.


<?php

function doubleSalt($toHash,$username){
$password = str_split($toHash,(strlen($toHash)/2)+1);
var_dump($password);
$hash = hash('md5', $username.$password[0].'centerSalt'.$password[1]);
return $hash;
}

?>

The str_split operation needs a +1 appended, otherwise the last character is cut off when the password is an odd number of characters, so that pass1 and pass2 will return the same value.

[NOTE BY danbrown AT php DOT net: Bug spotted by (Sunil) on 13-Mar-2009 and fix applied by OP.]

Leigh (06-Aug-2008 06:10)

Just a quick note about these benchmarks and how you should apply them.

If you are hashing passwords etc for security, speed is not your friend. You should use the slowest method.

Slow to hash means slow to crack and will hopefully make generating things like rainbow tables more trouble than it's worth.

The (27-May-2008 11:52)

Note that some of the hash algorithms provided are considered weak (e.g., md5, sha1 and haval128,3). If you have a choice in the matter, use ripemd160, whirlpool or tiger192,4.

inspiration3 at gmail dot com (04-May-2008 04:12)

Another comprehensive benchmark script that orders results from best to worst and includes the crc32(), md5() and sha1() standalone functions:

<?php

define('HASH_TIMES', 1000);
define('HASH_DATA', 'The quick brown fox jumped over!'); // 32 bytes

header('Content-Type: text/plain');
echo 'Testing ' . strlen(HASH_DATA) . ' bytes of data over ' . HASH_TIMES . " iterations:\n";

foreach (hash_algos() as $algo) {
    $time = microtime(1);
    for ($i = 0; $i < HASH_TIMES; $i++) hash($algo, HASH_DATA);
    $results[$algo] = microtime(1) - $time;
}

$time = microtime(1); for ($i = 0; $i < HASH_TIMES; $i++) crc32(HASH_DATA); $results['crc32()'] = microtime(1) - $time;
$time = microtime(1); for ($i = 0; $i < HASH_TIMES; $i++) md5(HASH_DATA); $results['md5()'] = microtime(1) - $time;
$time = microtime(1); for ($i = 0; $i < HASH_TIMES; $i++) sha1(HASH_DATA); $results['sha1()'] = microtime(1) - $time;

asort($results, SORT_NUMERIC);
foreach ($results as $algo => $time) echo "\n$time\t$algo";

?>

Marcus (27-Apr-2008 01:15)

A upgrade of (dani88elx AT gmail DOT com)'s performance test [from 26-Jun-2007], this time grading them by speed (fastest first) and comparing times between hex and raw data.

<?php
function testAlgos() {
$algos = hash_algos();
$word="This will be crypted by all different algoritms";
$results = array();
foreach($algos as $algo)
{
    $time=microtime(1);
    $data = hash($algo, $word, false);
    $results["".(microtime(1)-$time)][] = "$algo (hex)";
}
foreach($algos as $algo)
{
    $time=microtime(1);
    $data = hash($algo, $word, true);
    $results["".(microtime(1)-$time)][] = "$algo (raw)";
}
ksort($results);
foreach($results as $time => &$algos) {
    echo $time."\n";
    sort($algos);
    foreach($algos as $algo)
        echo "\t".$algo."\n";
}
}
testAlgos();
?>

mikael at webhost3 dot eu (10-Mar-2007 01:34)

<?php
$time=microtime(1);
for ($i=0;$i<100000;$i++)
   hash('md5', 'string');
echo microtime(1)-$time,': hash/md5<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   md5('string');
echo microtime(1)-$time,': md5<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   hash('sha1', 'string');
echo microtime(1)-$time,': hash/sha1<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   sha1('string');
echo microtime(1)-$time,': sha1<br>';
?>------------------------<br><?php
$time=microtime(1);
for ($i=0;$i<100000;$i++)
   hash('md5', $i);
echo microtime(1)-$time,': hash/md5<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   md5($i);
echo microtime(1)-$time,': md5<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   hash('sha1', $i);
echo microtime(1)-$time,': hash/sha1<br>';

$time=microtime(1);
for ($i=0;$i<100000;$i++)
   sha1($i);
echo microtime(1)-$time,': sha1<br>';
?>
Gives:
0.33311605453491: hash/md5
1.0671429634094: md5
0.383131980896: hash/sha1
1.3252220153809: sha1
------------------------
0.37684988975525: hash/md5
1.1258299350739: md5
0.43960785865784: hash/sha1
1.3876020908356: sha1