1:  2:  3:  4:  5:  6:  7:  8:  9: 10: 11: 12: 13: 14: 15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26: 27: 28: 29: 30: 31: 32: 33: 34: 35: 36: 37: 38: 39: 40: 41: 42: 43: 44: 45: 46: 47: 48: 

<?php

/**
 * Copyright 2016 LINE Corporation
 *
 * LINE Corporation licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

namespace LINE\LINEBot;

use LINE\LINEBot\Exception\InvalidSignatureException;

/**
 * A validator class of signature.
 *
 * @package LINE\LINEBot
 */
class SignatureValidator
{
    /**
     * Validate request with signature.
     *
     * @param string $body Request body.
     * @param string $channelSecret Your channel secret.
     * @param string $signature Signature (probably retrieve from HTTP header).
     * @return bool Request is valid or not.
     * @throws InvalidSignatureException When empty signature is given.
     */
    public static function validateSignature($body, $channelSecret, $signature)
    {
        if (!isset($signature)) {
            throw new InvalidSignatureException('Signature must not be empty');
        }

        return hash_equals(base64_encode(hash_hmac('sha256', $body, $channelSecret, true)), $signature);
    }
}