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<?php |
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/* |
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* Copyright (C) 2020 Jan Böhmer |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU Affero General Public License as published |
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* by the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU Affero General Public License for more details. |
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* |
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* You should have received a copy of the GNU Affero General Public License |
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* along with this program. If not, see <https://www.gnu.org/licenses/>. |
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*/ |
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declare(strict_types=1); |
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namespace App\Services\TFA; |
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use Exception; |
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use RuntimeException; |
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/** |
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* This class generates random backup codes for two factor authentication. |
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*/ |
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class BackupCodeGenerator |
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{ |
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protected $code_length; |
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protected $code_count; |
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/** |
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* BackupCodeGenerator constructor. |
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* |
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* @param int $code_length How many characters a single code should have. |
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* @param int $code_count How many codes are generated for a whole backup set. |
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*/ |
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public function __construct(int $code_length, int $code_count) |
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{ |
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if ($code_length > 32) { |
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throw new RuntimeException('Backup code can have maximum 32 digits!'); |
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} |
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if ($code_length < 6) { |
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throw new RuntimeException('Code must have at least 6 digits to ensure security!'); |
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} |
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$this->code_count = $code_count; |
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$this->code_length = $code_length; |
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} |
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/** |
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* Generates a single backup code. |
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* It is a random hexadecimal value with the digit count configured in constructor. |
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* |
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* @return string The generated backup code (e.g. 1f3870be2) |
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* |
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* @throws Exception If no entropy source is available. |
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*/ |
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public function generateSingleCode(): string |
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{ |
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$bytes = random_bytes(32); |
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return substr(md5($bytes), 0, $this->code_length); |
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} |
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/** |
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* Returns a full backup code set. The code count can be configured in the constructor. |
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* |
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* @return string[] An array containing different backup codes. |
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*/ |
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public function generateCodeSet(): array |
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{ |
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$array = []; |
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for ($n = 0; $n < $this->code_count; ++$n) { |
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$array[] = $this->generateSingleCode(); |
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} |
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return $array; |
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} |
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} |
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jbtronics /
StuRa-Finanzsoftware
