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| Rev | Author | Line No. | Line |
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| 2 | daniel-mar | 1 | <?php |
| 2 | |||
| 3 | /* |
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| 4 | * php_clientchallenge |
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| 6 | daniel-mar | 5 | * Copyright 2021-2022 Daniel Marschall, ViaThinkSoft |
| 2 | daniel-mar | 6 | * |
| 7 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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| 8 | * you may not use this file except in compliance with the License. |
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| 9 | * You may obtain a copy of the License at |
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| 10 | * |
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| 11 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 12 | * |
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| 13 | * Unless required by applicable law or agreed to in writing, software |
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| 14 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 15 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 16 | * See the License for the specific language governing permissions and |
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| 17 | * limitations under the License. |
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| 18 | */ |
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| 19 | |||
| 20 | namespace ViaThinkSoft\RateLimitingChallenge; |
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| 21 | |||
| 22 | class ClientChallenge { |
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| 23 | |||
| 6 | daniel-mar | 24 | const OPEN_TRANS_DIR = __DIR__.'/cache'; |
| 25 | |||
| 4 | daniel-mar | 26 | private static function sha3_512($message, $raw_output=false) { |
| 2 | daniel-mar | 27 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
| 4 | daniel-mar | 28 | return hash('sha3-512', $message, $raw_output); |
| 2 | daniel-mar | 29 | } else { |
| 6 | daniel-mar | 30 | // Download file if required (usually composer should do it) |
| 31 | if (file_exists(__DIR__.'/Sha3.php')) include_once __DIR__.'/Sha3.php'; |
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| 32 | if (!class_exists('\bb\Sha3\Sha3')) { |
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| 33 | $sha3_lib = file_get_contents('https://raw.githubusercontent.com/danielmarschall/php-sha3/master/src/Sha3.php'); |
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| 34 | if (file_put_contents(__DIR__.'/Sha3.php', $sha3_lib)) { |
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| 35 | include_once __DIR__.'/Sha3.php'; |
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| 36 | } else { |
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| 37 | eval('?>'.$sha3_lib); |
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| 38 | } |
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| 39 | } |
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| 40 | return \bb\Sha3\Sha3::hash($message, 512, $raw_output); |
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| 2 | daniel-mar | 41 | } |
| 42 | } |
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| 43 | |||
| 4 | daniel-mar | 44 | private static function sha3_512_hmac($message, $key, $raw_output=false) { |
| 45 | // RFC 2104 HMAC |
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| 46 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
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| 47 | return hash_hmac('sha3-512', $message, $key, $raw_output); |
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| 48 | } else { |
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| 49 | $blocksize = 576; // block size of sha-512! |
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| 2 | daniel-mar | 50 | |
| 4 | daniel-mar | 51 | if (strlen($key) > ($blocksize/8)) { |
| 5 | daniel-mar | 52 | $k_ = self::sha3_512($key,true); |
| 4 | daniel-mar | 53 | } else { |
| 54 | $k_ = $key; |
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| 55 | } |
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| 2 | daniel-mar | 56 | |
| 4 | daniel-mar | 57 | $k_opad = str_repeat(chr(0x5C),($blocksize/8)); |
| 58 | $k_ipad = str_repeat(chr(0x36),($blocksize/8)); |
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| 59 | for ($i=0; $i<strlen($k_); $i++) { |
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| 60 | $k_opad[$i] = $k_opad[$i] ^ $k_[$i]; |
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| 61 | $k_ipad[$i] = $k_ipad[$i] ^ $k_[$i]; |
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| 62 | } |
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| 2 | daniel-mar | 63 | |
| 5 | daniel-mar | 64 | return self::sha3_512($k_opad . self::sha3_512($k_ipad . $message, true)); |
| 4 | daniel-mar | 65 | } |
| 66 | } |
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| 67 | |||
| 6 | daniel-mar | 68 | private static function getOpenTransFileName($ip_target, $random) { |
| 69 | // Delete challenges which were never completed |
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| 70 | $files = glob(self::OPEN_TRANS_DIR.'/*.tmp'); |
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| 71 | $expire = strtotime('-3 DAYS'); |
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| 72 | foreach ($files as $file) { |
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| 73 | if (!is_file($file)) continue; |
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| 74 | if (filemtime($file) > $expire) continue; |
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| 75 | @unlink($file); |
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| 76 | } |
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| 4 | daniel-mar | 77 | |
| 6 | daniel-mar | 78 | return self::OPEN_TRANS_DIR.'/'.self::sha3_512($ip_target.'/'.$random).'.tmp'; |
| 79 | } |
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| 4 | daniel-mar | 80 | |
| 6 | daniel-mar | 81 | public static function checkValidation($client_response, $max_time=10, $server_secret) { |
| 82 | list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = $client_response; |
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| 83 | $open_trans_file = self::getOpenTransFileName($ip_target, $answer); |
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| 4 | daniel-mar | 84 | |
| 2 | daniel-mar | 85 | if ($ip_target != $_SERVER['REMOTE_ADDR']) { |
| 4 | daniel-mar | 86 | throw new \Exception('Wrong IP'); |
| 2 | daniel-mar | 87 | } else if (time()-$starttime > $max_time) { |
| 4 | daniel-mar | 88 | throw new \Exception('Challenge expired'); |
| 89 | } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) { |
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| 90 | throw new \Exception('Challenge integrity failed'); |
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| 2 | daniel-mar | 91 | } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) { |
| 4 | daniel-mar | 92 | throw new \Exception('Wrong answer'); |
| 6 | daniel-mar | 93 | } else if (!file_exists($open_trans_file)) { |
| 94 | throw new \Exception('Challenge submitted twice or transaction missing'); |
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| 2 | daniel-mar | 95 | } else { |
| 6 | daniel-mar | 96 | unlink($open_trans_file); |
| 2 | daniel-mar | 97 | return true; |
| 98 | } |
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| 99 | } |
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| 100 | |||
| 6 | daniel-mar | 101 | public static function createChallenge($complexity=50000, $server_secret) { |
| 102 | $offset = 0; // doesn't matter |
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| 103 | $min = $offset; |
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| 104 | $max = $offset + $complexity; |
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| 2 | daniel-mar | 105 | |
| 106 | $starttime = time(); |
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| 107 | |||
| 108 | $random = rand($min,$max); // TODO: cryptographic rand |
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| 109 | |||
| 110 | $ip_target = $_SERVER['REMOTE_ADDR']; |
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| 111 | |||
| 112 | $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random); |
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| 113 | |||
| 4 | daniel-mar | 114 | $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret); |
| 2 | daniel-mar | 115 | |
| 4 | daniel-mar | 116 | $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity); |
| 117 | |||
| 6 | daniel-mar | 118 | $open_trans_file = self::getOpenTransFileName($ip_target, $random); |
| 119 | if (@file_put_contents($open_trans_file, '') === false) { |
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| 120 | throw new \Exception("Cannot write $open_trans_file"); |
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| 121 | } |
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| 2 | daniel-mar | 122 | |
| 6 | daniel-mar | 123 | return $send_to_client; |
| 2 | daniel-mar | 124 | } |
| 125 | |||
| 126 | } |