src/Module/Authentication/LocalAuth/LocalAuth.php
protected function needsPasswordRehash(array $userData)
    {
        // Return if password rehashing is not enabled
        if ($this->config["login"]["passwordRehash"] !== true) {
            return false;
        }

        // Password hash is created using a different algorithm than default
        if (isset($userData['encoder']) && $userData['encoder'] !== $this->config["encoder"]) {
            return true;
        }
        $encoder = $this->getPasswordEncoder($userData);

        // If password hash algorithm options have changed
        return $encoder->needsRehash($userData['pwhash']);
    }
protected function needsPasswordRehash(array $userData)
    {
        // Return if password rehashing is not enabled
        if ($this->config["login"]["passwordRehash"] !== true) {
            return false;
        }

        // Password hash is created using a different algorithm than default
        if (isset($userData['encoder']) && $userData['encoder'] !== $this->config["encoder"]) {
            return true;
        }
        $encoder = $this->getPasswordEncoder($userData);

        // If password hash algorithm options have changed
        return $encoder->needsRehash($userData['pwhash']);
    }
Returns whether a rehash is needed

@param array $userData User data array
@return boolean true if needed, false otherwise