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<?php
/**
* Copyright 2017 Facebook, Inc.
*
* You are hereby granted a non-exclusive, worldwide, royalty-free license to
* use, copy, modify, and distribute this software in source code or binary
* form for use in connection with the web services and APIs provided by
* Facebook.
*
* As with any software that integrates with the Facebook platform, your use
* of this software is subject to the Facebook Developer Principles and
* Policies [http://developers.facebook.com/policy/]. This copyright notice
* shall be included in all copies or substantial portions of the software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
*/
/**
* @see https://github.com/sarciszewski/php-future/blob/master/src/Security.php#L37-L51
*/
if (!function_exists('hash_equals')) {
function hash_equals($knownString, $userString)
{
if (function_exists('mb_strlen')) {
$kLen = mb_strlen($knownString, '8bit');
$uLen = mb_strlen($userString, '8bit');
} else {
$kLen = strlen($knownString);
$uLen = strlen($userString);
}
if ($kLen !== $uLen) {
return false;
}
$result = 0;
for ($i = 0; $i < $kLen; $i++) {
$result |= (ord($knownString[$i]) ^ ord($userString[$i]));
}
// They are only identical strings if $result is exactly 0...
return 0 === $result;
}
}
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