Magento version

Full Error:

Fatal error: Call to undefined function hash_equals() in /var/www/vhosts/lassco/htdocs/app/code/core/Mage/Core/Model/Encryption.php on line 103

This occurs when I enter my admin details to login to the magento cms

I've checked my functions.php file and it seems to be patched correctly with the following code at the end of the file.

if (!function_exists('hash_equals')) {
     * Compares two strings using the same time whether they're equal or not.
     * A difference in length will leak
     * @param string $known_string
     * @param string $user_string
     * @return boolean Returns true when the two strings are equal, false otherwise.
    function hash_equals($known_string, $user_string)
        $result = 0;

        if (!is_string($known_string)) {
            trigger_error("hash_equals(): Expected known_string to be a string", E_USER_WARNING);
            return false;

        if (!is_string($user_string)) {
            trigger_error("hash_equals(): Expected user_string to be a string", E_USER_WARNING);
            return false;

        if (strlen($known_string) != strlen($user_string)) {
            return false;

        for ($i = 0; $i < strlen($known_string); $i++) {
            $result |= (ord($known_string[$i]) ^ ord($user_string[$i]));

        return 0 === $result;

Any help would be appreciated, thank you

2 Answers 2


hash_equals are not available on PHP versions prior to 5.6

  • The patch in the functions.php file covers that issue
    – GApple
    Nov 21, 2017 at 11:29

This library has a bug.

Mage.php line 51 uses

include_once "Mage/Core/functions.php";

When it should be

include_once "app/code/core/Mage/Core/functions.php";

This is only the case for when trying to login on the admin page though

A fix would be great

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