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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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5 | * Copyright 2021 Daniel Marschall, ViaThinkSoft |
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6 | * |
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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 | |||
4 | daniel-mar | 24 | private static function sha3_512($message, $raw_output=false) { |
2 | daniel-mar | 25 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
4 | daniel-mar | 26 | return hash('sha3-512', $message, $raw_output); |
2 | daniel-mar | 27 | } else { |
4 | daniel-mar | 28 | return \bb\Sha3\Sha3::hash($message, 512, $raw_output); |
2 | daniel-mar | 29 | } |
30 | } |
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31 | |||
4 | daniel-mar | 32 | private static function sha3_512_hmac($message, $key, $raw_output=false) { |
33 | // RFC 2104 HMAC |
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34 | if (version_compare(PHP_VERSION, '7.1.0') >= 0) { |
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35 | return hash_hmac('sha3-512', $message, $key, $raw_output); |
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36 | } else { |
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37 | $blocksize = 576; // block size of sha-512! |
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2 | daniel-mar | 38 | |
4 | daniel-mar | 39 | if (strlen($key) > ($blocksize/8)) { |
40 | $k_ = sha3_512($key,true); |
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41 | } else { |
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42 | $k_ = $key; |
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43 | } |
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2 | daniel-mar | 44 | |
4 | daniel-mar | 45 | $k_opad = str_repeat(chr(0x5C),($blocksize/8)); |
46 | $k_ipad = str_repeat(chr(0x36),($blocksize/8)); |
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47 | for ($i=0; $i<strlen($k_); $i++) { |
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48 | $k_opad[$i] = $k_opad[$i] ^ $k_[$i]; |
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49 | $k_ipad[$i] = $k_ipad[$i] ^ $k_[$i]; |
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50 | } |
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2 | daniel-mar | 51 | |
4 | daniel-mar | 52 | return sha3_512($k_opad . sha3_512($k_ipad . $message, true)); |
53 | } |
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54 | } |
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55 | |||
56 | public static function checkValidation($max_time=10, $server_secret) { |
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57 | |||
58 | if (!isset($_REQUEST['vts_validation_result'])) throw new \Exception('No challenge response found'); |
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59 | |||
60 | list($starttime, $ip_target, $challenge, $answer, $challenge_integrity) = @json_decode($_REQUEST['vts_validation_result'], true); |
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61 | |||
2 | daniel-mar | 62 | if ($ip_target != $_SERVER['REMOTE_ADDR']) { |
4 | daniel-mar | 63 | throw new \Exception('Wrong IP'); |
2 | daniel-mar | 64 | } else if (time()-$starttime > $max_time) { |
4 | daniel-mar | 65 | throw new \Exception('Challenge expired'); |
66 | } else if ($challenge_integrity != self::sha3_512_hmac($challenge,$server_secret)) { |
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67 | throw new \Exception('Challenge integrity failed'); |
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2 | daniel-mar | 68 | } else if ($challenge !== self::sha3_512($starttime.'/'.$ip_target.'/'.$answer)) { |
4 | daniel-mar | 69 | throw new \Exception('Wrong answer'); |
2 | daniel-mar | 70 | } else { |
71 | return true; |
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72 | } |
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73 | } |
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74 | |||
75 | // This is only called by ajax_get_challenge.php |
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4 | daniel-mar | 76 | public static function createChallenge($complexity=500000, $server_secret) { |
2 | daniel-mar | 77 | |
78 | $min = 0; |
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79 | $max = $complexity; |
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80 | |||
81 | $starttime = time(); |
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82 | |||
83 | $random = rand($min,$max); // TODO: cryptographic rand |
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84 | |||
85 | $ip_target = $_SERVER['REMOTE_ADDR']; |
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86 | |||
87 | $challenge = self::sha3_512($starttime.'/'.$ip_target.'/'.$random); |
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88 | |||
4 | daniel-mar | 89 | $challenge_integrity = self::sha3_512_hmac($challenge,$server_secret); |
2 | daniel-mar | 90 | |
4 | daniel-mar | 91 | $send_to_client = array($starttime, $ip_target, $challenge, $min, $max, $challenge_integrity); |
92 | |||
2 | daniel-mar | 93 | header('Content-Type:application/json'); |
94 | die(json_encode($send_to_client)); |
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95 | |||
96 | } |
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97 | |||
98 | } |