40 lines
1.2 KiB
PHP
40 lines
1.2 KiB
PHP
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<?php
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namespace Misuzu;
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use Index\Serialisation\Serialiser;
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class TOTP {
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public const DIGITS = 6;
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public const INTERVAL = 30;
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public const HASH_ALGO = 'sha1';
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private $secretKey;
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public function __construct(string $secretKey) {
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$this->secretKey = $secretKey;
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}
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public static function generateKey(): string {
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return Serialiser::base32()->serialise(random_bytes(16));
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}
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public static function timecode(?int $timestamp = null, int $interval = self::INTERVAL): int {
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$timestamp = $timestamp ?? time();
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return (int)(($timestamp * 1000) / ($interval * 1000));
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}
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public function generate(?int $timestamp = null): string {
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$hash = hash_hmac(self::HASH_ALGO, pack('J', self::timecode($timestamp)), Serialiser::base32()->deserialise($this->secretKey), true);
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$offset = ord($hash[strlen($hash) - 1]) & 0x0F;
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$bin = 0;
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$bin |= (ord($hash[$offset]) & 0x7F) << 24;
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$bin |= (ord($hash[$offset + 1]) & 0xFF) << 16;
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$bin |= (ord($hash[$offset + 2]) & 0xFF) << 8;
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$bin |= (ord($hash[$offset + 3]) & 0xFF);
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$otp = $bin % pow(10, self::DIGITS);
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return str_pad(strval($otp), self::DIGITS, '0', STR_PAD_LEFT);
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}
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}
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