126 lines
4.1 KiB
PHP
126 lines
4.1 KiB
PHP
<?php
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namespace ParagonIE\ConstantTime;
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/**
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* Copyright (c) 2016 - 2017 Paragon Initiative Enterprises.
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* Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* Class Hex
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* @package ParagonIE\ConstantTime
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*/
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abstract class Hex implements EncoderInterface
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{
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/**
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* Convert a binary string into a hexadecimal string without cache-timing
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* leaks
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*
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* @param string $bin_string (raw binary)
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* @return string
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*/
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public static function encode($bin_string)
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{
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$hex = '';
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$len = Binary::safeStrlen($bin_string);
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for ($i = 0; $i < $len; ++$i) {
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$chunk = \unpack('C', Binary::safeSubstr($bin_string, $i, 2));
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$c = $chunk[1] & 0xf;
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$b = $chunk[1] >> 4;
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$hex .= pack(
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'CC',
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(87 + $b + ((($b - 10) >> 8) & ~38)),
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(87 + $c + ((($c - 10) >> 8) & ~38))
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);
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}
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return $hex;
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}
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/**
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* Convert a binary string into a hexadecimal string without cache-timing
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* leaks, returning uppercase letters (as per RFC 4648)
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*
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* @param string $bin_string (raw binary)
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* @return string
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*/
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public static function encodeUpper($bin_string)
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{
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$hex = '';
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$len = Binary::safeStrlen($bin_string);
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for ($i = 0; $i < $len; ++$i) {
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$chunk = \unpack('C', Binary::safeSubstr($bin_string, $i, 2));
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$c = $chunk[1] & 0xf;
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$b = $chunk[1] >> 4;
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$hex .= pack(
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'CC',
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(55 + $b + ((($b - 10) >> 8) & ~6)),
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(55 + $c + ((($c - 10) >> 8) & ~6))
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);
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}
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return $hex;
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}
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/**
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* Convert a hexadecimal string into a binary string without cache-timing
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* leaks
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*
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* @param string $hex_string
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* @return string (raw binary)
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* @throws \RangeException
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*/
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public static function decode($hex_string)
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{
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$hex_pos = 0;
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$bin = '';
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$c_acc = 0;
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$hex_len = Binary::safeStrlen($hex_string);
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$state = 0;
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if (($hex_len & 1) !== 0) {
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throw new \RangeException(
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'Expected an even number of hexadecimal characters'
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);
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}
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$chunk = \unpack('C*', $hex_string);
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while ($hex_pos < $hex_len) {
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++$hex_pos;
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$c = $chunk[$hex_pos];
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$c_num = $c ^ 48;
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$c_num0 = ($c_num - 10) >> 8;
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$c_alpha = ($c & ~32) - 55;
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$c_alpha0 = (($c_alpha - 10) ^ ($c_alpha - 16)) >> 8;
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if (($c_num0 | $c_alpha0) === 0) {
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throw new \RangeException(
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'hexEncode() only expects hexadecimal characters'
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);
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}
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$c_val = ($c_num0 & $c_num) | ($c_alpha & $c_alpha0);
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if ($state === 0) {
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$c_acc = $c_val * 16;
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} else {
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$bin .= \pack('C', $c_acc | $c_val);
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}
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$state ^= 1;
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}
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return $bin;
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}
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}
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