PHP 7.2.0 Beta 1 Released

hash_pbkdf2

(PHP 5 >= 5.5.0, PHP 7)

hash_pbkdf2PBKDF2 を使ってパスワードからキーを生成する

説明

string hash_pbkdf2 ( string $algo , string $password , string $salt , int $iterations [, int $length = 0 [, bool $raw_output = false ]] )

パラメータ

algo

ハッシュアルゴリズムの名前 (たとえば md5, sha256, haval160,4 など)。サポートされるアルゴリズムの一覧は hash_algos() をご参照ください。

password

派生に使うパスワード

salt

派生に使うソルト。ランダムに生成した値でなければいけません。

iterations

派生の実行の際の内部の反復回数

length

出力する文字列の長さ。raw_outputTRUE の場合、これは派生キーのバイト長になります。 raw_outputFALSE の場合、 これは派生キーのバイト長の二倍になります (キーの全バイトが十六進二桁で返されるからです)。

raw_output

TRUE にセットされている場合、名前のバイナリデータが出力されます。FALSE の場合、小文字の16進数が出力されます。

返り値

小文字の16進数を含む文字列が返されます。raw_outputTRUE の場合、派生キーの生のバイナリ表現が返されます。

エラー / 例外

E_WARNING が発生するのはアルゴリズムが未知である場合、iterations パラメータが 0 以下である場合、length0 以下である場合、salt が長すぎる場合 (INT_MAX - 4 よりも大きい) です。

変更履歴

バージョン 説明
7.2.0 Usage of non-cryptographic hash functions (adler32, crc32, crc32b, fnv132, fnv1a32, fnv164, fnv1a64, joaat) was disabled.

例1 hash_pbkdf2() の基本的な使い方の例

<?php
$password 
"password";
$iterations 1000;

// ランダムな IV を、mcrypt_create_iv() や
// openssl_random_pseudo_bytes() などの適切なソースを使って生成します。
$salt mcrypt_create_iv(16MCRYPT_DEV_URANDOM);

$hash hash_pbkdf2("sha256"$password$salt$iterations20);
echo 
$hash;
?>

上の例の出力は、 たとえば以下のようになります。

120fb6cffcf8b32c43e7

注意

警告

PBKDF2 による方法はパスワードのハッシュを保存するために使うことができます。 しかし、password_hash()crypt()CRYPT_BLOWFISH を使うのほうが、パスワードの保存に適しています。

参考

  • crypt() - 文字列の一方向のハッシュ化を行う
  • password_hash() - パスワードハッシュを作る
  • hash() - ハッシュ値 (メッセージダイジェスト) を生成する
  • hash_algos() - 登録されているハッシュアルゴリズムの一覧を返す
  • hash_init() - 段階的なハッシュコンテキストを初期化する
  • hash_hmac() - HMAC 方式を使用してハッシュ値を生成する
  • hash_hmac_file() - HMAC 方式を使用して、指定されたファイルの内容からハッシュ値を生成する

add a note add a note

User Contributed Notes 7 notes

up
10
clarence.pchy(at)gmail.com
10 months ago
Please pay great attention to the **$length** parameter! It is exactly the **return string length**, NOT the length of raw binary hash result.

I had a big problem about this --
I thought that `hash_pbkdf2(...false)` should equals to `bin2hex(hash_pbkdf2(...true))` just like `md5($x)` equals `bin2hex(md5($x, true))`. However I was wrong:

hash_pbkdf2('sha256', '123456', 'abc', 10000, 50, false); // returns string(50) "584bc5b41005169f1fa15177edb78d75f9846afc466a4bae05"
hash_pbkdf2('sha256', '123456', 'abc', 10000, 50, true); // returns string(50) "XKŴ��Qw�u��j�FjK���BFW�YpG    �mp.g2�`;N�"
bin2hex(hash_pbkdf2('sha256', '123456', 'abc', 10000, 50, true)); // returns string(100) "584bc5b41005169f1fa15177edb78d75f9846afc466a4bae05119c82424657c81b5970471f098a6d702e6732b7603b194efe"

So I add such a note. Hope it will help someone else like me.
up
9
Anonymous
4 years ago
Sadly this function was added in PHP 5.5 but many webservers just provide PHP 5.3. But there exists a pure PHP implementation (found here: https://defuse.ca/php-pbkdf2.htm).
I took this implementation, put it into a class with comments for PHPDoc and added a switch so that the native PHP function is used if available.

Feel free to use it!
http://pastebin.com/f5PDq735
(Posted on pastebin.com since the text would have been too long)
up
5
Trevor Herselman
1 year ago
This is a light-weight drop-in replacement for PHP's hash_pbkdf2(); written for compatibility with older versions of PHP.
Written, formatted and tested by myself, but using code and ideas based on the following:
https://defuse.ca/php-pbkdf2.htm
https://github.com/rchouinard/hash_pbkdf2-compat/blob/master/src/hash_pbkdf2.php
https://gist.github.com/rsky/5104756

My main goals:
1) Maximum compatibility with PHP hash_pbkdf2(), ie. a drop-in replacement function
2) Minimum code size/bloat
3) Easy to copy/paste
4) No classes, and not encapsulated in a class! Why write a class when a simple function will do?
5) Eliminate calls to sprintf(). (used by other examples for the error reporting)
6) No other dependencies, ie. extra required functions

<?php
if (!function_exists('hash_pbkdf2'))
{
    function
hash_pbkdf2($algo, $password, $salt, $count, $length = 0, $raw_output = false)
    {
        if (!
in_array(strtolower($algo), hash_algos())) trigger_error(__FUNCTION__ . '(): Unknown hashing algorithm: ' . $algo, E_USER_WARNING);
        if (!
is_numeric($count)) trigger_error(__FUNCTION__ . '(): expects parameter 4 to be long, ' . gettype($count) . ' given', E_USER_WARNING);
        if (!
is_numeric($length)) trigger_error(__FUNCTION__ . '(): expects parameter 5 to be long, ' . gettype($length) . ' given', E_USER_WARNING);
        if (
$count <= 0) trigger_error(__FUNCTION__ . '(): Iterations must be a positive integer: ' . $count, E_USER_WARNING);
        if (
$length < 0) trigger_error(__FUNCTION__ . '(): Length must be greater than or equal to 0: ' . $length, E_USER_WARNING);

       
$output = '';
       
$block_count = $length ? ceil($length / strlen(hash($algo, '', $raw_output))) : 1;
        for (
$i = 1; $i <= $block_count; $i++)
        {
           
$last = $xorsum = hash_hmac($algo, $salt . pack('N', $i), $password, true);
            for (
$j = 1; $j < $count; $j++)
            {
               
$xorsum ^= ($last = hash_hmac($algo, $last, $password, true));
            }
           
$output .= $xorsum;
        }

        if (!
$raw_output) $output = bin2hex($output);
        return
$length ? substr($output, 0, $length) : $output;
    }
}
up
5
does dot not at matter dot org
3 years ago
this snippet was posted over a year ago on a dutch PHP community: (reference/source: http://www.phphulp.nl/php/script/beveiliging/pbkdf2-een-veilige-manier-om-wachtwoorden-op-te-slaan/1956/pbkdf2php/1757/)

<?php

/**
* @author Chris Horeweg
* @package Security_Tools
*/

function pbkdf2($password, $salt, $algorithm = 'sha512', $count = 20000, $key_length = 128, $raw_output = false)
{
    if(!
in_array($algorithm, hash_algos(), true)) {
        exit(
'pbkdf2: Hash algoritme is niet geinstalleerd op het systeem.');
    }
   
    if(
$count <= 0 || $key_length <= 0) {
       
$count = 20000;
       
$key_length = 128;
    }

   
$hash_length = strlen(hash($algorithm, "", true));
   
$block_count = ceil($key_length / $hash_length);

   
$output = "";
    for(
$i = 1; $i <= $block_count; $i++) {
       
$last = $salt . pack("N", $i);
       
$last = $xorsum = hash_hmac($algorithm, $last, $password, true);
        for (
$j = 1; $j < $count; $j++) {
           
$xorsum ^= ($last = hash_hmac($algorithm, $last, $password, true));
        }
       
$output .= $xorsum;
    }

    if(
$raw_output) {
        return
substr($output, 0, $key_length);
    }
    else {
        return
base64_encode(substr($output, 0, $key_length));
    }
}
up
1
Binod Kumar Luitel
3 years ago
People who wants pure PHP implementation of the function, i.e. who don't have PHP 5.5 installed within their server, can use the following implementation. Nothing has been modified so far as from reference https://defuse.ca/php-pbkdf2.htm but the OOP lovers might like this.
For more information about PBKDF2 see: http://en.wikipedia.org/wiki/PBKDF2

<?php
/**
* PBKDF2 key derivation function as defined by RSA's PKCS #5: https://www.ietf.org/rfc/rfc2898.txt
* $algorithm - The hash algorithm to use. Recommended: SHA256
* $password - The password.
* $salt - A salt that is unique to the password.
* $count - Iteration count. Higher is better, but slower. Recommended: At least 1000.
* $key_length - The length of the derived key in bytes.
* $raw_output - If true, the key is returned in raw binary format. Hex encoded otherwise.
* Returns: A $key_length-byte key derived from the password and salt.
*/
if (!function_exists("hash_pbkdf2")) {
    function
hash_pbkdf2($algorithm, $password, $salt, $count, $key_length, $raw_output = false) {

        class
pbkdf2 {
            public
$algorithm;
            public
$password;
            public
$salt;
            public
$count;
            public
$key_length;
            public
$raw_output;

            private
$hash_length;
            private
$output         = "";

            public function
__construct($data = null)
            {
                if (
$data != null) {
                   
$this->init($data);
                }
            }

            public function
init($data)
            {
               
$this->algorithm  = $data["algorithm"];
               
$this->password   = $data["password"];
               
$this->salt       = $data["salt"];
               
$this->count      = $data["count"];
               
$this->key_length = $data["key_length"];
               
$this->raw_output = $data["raw_output"];
            }

            public function
hash()
            {
               
$this->algorithm = strtolower($this->algorithm);
                if(!
in_array($this->algorithm, hash_algos(), true))
                    throw new
Exception('PBKDF2 ERROR: Invalid hash algorithm.');

                if(
$this->count <= 0 || $this->key_length <= 0)
                    throw new
Exception('PBKDF2 ERROR: Invalid parameters.');

               
$this->hash_length = strlen(hash($this->algorithm, "", true));
               
$block_count = ceil($this->key_length / $this->hash_length);
                for (
$i = 1; $i <= $block_count; $i++) {
                   
// $i encoded as 4 bytes, big endian.
                   
$last = $this->salt . pack("N", $i);
                   
// first iteration
                   
$last = $xorsum = hash_hmac($this->algorithm, $last, $this->password, true);
                   
// perform the other $this->count - 1 iterations
                   
for ($j = 1; $j < $this->count; $j++) {
                       
$xorsum ^= ($last = hash_hmac($this->algorithm, $last, $this->password, true));
                    }
                   
$this->output .= $xorsum;
                    if(
$this->raw_output)
                        return
substr($this->output, 0, $this->key_length);
                    else
                        return
bin2hex(substr($this->output, 0, $this->key_length));
                }
            }
        }

       
$data = array('algorithm' => $algorithm, 'password' => $password, 'salt' => $salt, 'count' => $count, 'key_length' => $key_length, 'raw_output' => $raw_output);
        try {
           
$pbkdf2 = new pbkdf2($data);
            return
$pbkdf2->hash();
        } catch (
Exception $e) {
            throw
$e;
        }
    }
}
up
1
nimasdj [AT] yahoo [DOT] com
1 year ago
There is a mistake in the class provided by Binod Kumar Luitel (http://php.net/manual/en/function.hash-pbkdf2.php#113488):
this line:
return bin2hex(substr($this->output, 0, $this->key_length));
must be changed to:
return substr(bin2hex($this->output), 0, $this->key_length);
up
-1
Peter
3 years ago
See also https://github.com/rchouinard/hash_pbkdf2-compat for a compatibility function
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