123 lines
4.3 KiB
PHP
123 lines
4.3 KiB
PHP
<?php
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/**
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* @file
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* Contains \Drupal\Component\Utility\Crypt.
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*/
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namespace Drupal\Component\Utility;
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/**
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* Utility class for cryptographically-secure string handling routines.
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*/
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class Crypt {
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/**
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* Returns a string of highly randomized bytes (over the full 8-bit range).
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*
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* This function is better than simply calling mt_rand() or any other built-in
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* PHP function because it can return a long string of bytes (compared to < 4
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* bytes normally from mt_rand()) and uses the best available pseudo-random
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* source.
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*
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* @param int $count
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* The number of characters (bytes) to return in the string.
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*
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* @return string
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* A randomly generated string.
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*/
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public static function randomBytes($count) {
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static $random_state, $bytes;
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// Initialize on the first call. The contents of $_SERVER includes a mix of
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// user-specific and system information that varies a little with each page.
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// Further initialize with the somewhat random PHP process ID.
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if (!isset($random_state)) {
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$random_state = print_r($_SERVER, TRUE) . getmypid();
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$bytes = '';
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}
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if (strlen($bytes) < $count) {
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// /dev/urandom is available on many *nix systems and is considered the
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// best commonly available pseudo-random source.
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if ($fh = @fopen('/dev/urandom', 'rb')) {
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// PHP only performs buffered reads, so in reality it will always read
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// at least 4096 bytes. Thus, it costs nothing extra to read and store
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// that much so as to speed any additional invocations.
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$bytes .= fread($fh, max(4096, $count));
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fclose($fh);
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}
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// openssl_random_pseudo_bytes() will find entropy in a system-dependent
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// way.
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elseif (function_exists('openssl_random_pseudo_bytes')) {
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$bytes .= openssl_random_pseudo_bytes($count - strlen($bytes));
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}
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// If /dev/urandom is not available or returns no bytes, this loop will
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// generate a good set of pseudo-random bytes on any system.
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// Note that it may be important that our $random_state is passed
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// through hash() prior to being rolled into $output, that the two hash()
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// invocations are different, and that the extra input into the first one -
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// the microtime() - is prepended rather than appended. This is to avoid
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// directly leaking $random_state via the $output stream, which could
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// allow for trivial prediction of further "random" numbers.
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while (strlen($bytes) < $count) {
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$random_state = hash('sha256', microtime() . mt_rand() . $random_state);
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$bytes .= hash('sha256', mt_rand() . $random_state, TRUE);
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}
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}
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$output = substr($bytes, 0, $count);
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$bytes = substr($bytes, $count);
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return $output;
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}
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/**
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* Calculates a base-64 encoded, URL-safe sha-256 hmac.
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*
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* @param string $data
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* String to be validated with the hmac.
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* @param string $key
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* A secret string key.
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*
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* @return string
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* A base-64 encoded sha-256 hmac, with + replaced with -, / with _ and
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* any = padding characters removed.
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*/
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public static function hmacBase64($data, $key) {
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$hmac = base64_encode(hash_hmac('sha256', $data, $key, TRUE));
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// Modify the hmac so it's safe to use in URLs.
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return strtr($hmac, array('+' => '-', '/' => '_', '=' => ''));
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}
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/**
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* Calculates a base-64 encoded, URL-safe sha-256 hash.
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*
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* @param string $data
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* String to be hashed.
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*
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* @return string
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* A base-64 encoded sha-256 hash, with + replaced with -, / with _ and
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* any = padding characters removed.
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*/
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public static function hashBase64($data) {
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$hash = base64_encode(hash('sha256', $data, TRUE));
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// Modify the hash so it's safe to use in URLs.
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return strtr($hash, array('+' => '-', '/' => '_', '=' => ''));
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}
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/**
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* Generates a random, base-64 encoded, URL-safe, sha-256 hashed string.
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*
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* @param int $count
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* The number of characters (bytes) of the string to be hashed.
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*
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* @return string
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* A base-64 encoded sha-256 hash, with + replaced with -, / with _ and
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* any = padding characters removed.
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*
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* @see \Drupal\Component\Utility\Crypt::randomBytes()
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* @see \Drupal\Component\Utility\Crypt::hashBase64()
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*/
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public static function randomStringHashed($count) {
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return static::hashBase64(static::randomBytes($count));
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}
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}
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