1<?php 2declare(strict_types=1); 3namespace ParagonIE\ConstantTime; 4 5use RangeException; 6use TypeError; 7 8/** 9 * Copyright (c) 2016 - 2022 Paragon Initiative Enterprises. 10 * Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com) 11 * 12 * Permission is hereby granted, free of charge, to any person obtaining a copy 13 * of this software and associated documentation files (the "Software"), to deal 14 * in the Software without restriction, including without limitation the rights 15 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 16 * copies of the Software, and to permit persons to whom the Software is 17 * furnished to do so, subject to the following conditions: 18 * 19 * The above copyright notice and this permission notice shall be included in all 20 * copies or substantial portions of the Software. 21 * 22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 27 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 28 * SOFTWARE. 29 */ 30 31/** 32 * Class Hex 33 * @package ParagonIE\ConstantTime 34 */ 35abstract class Hex implements EncoderInterface 36{ 37 /** 38 * Convert a binary string into a hexadecimal string without cache-timing 39 * leaks 40 * 41 * @param string $binString (raw binary) 42 * @return string 43 * @throws TypeError 44 */ 45 public static function encode( 46 #[\SensitiveParameter] 47 string $binString 48 ): string { 49 $hex = ''; 50 $len = Binary::safeStrlen($binString); 51 for ($i = 0; $i < $len; ++$i) { 52 /** @var array<int, int> $chunk */ 53 $chunk = \unpack('C', $binString[$i]); 54 $c = $chunk[1] & 0xf; 55 $b = $chunk[1] >> 4; 56 57 $hex .= \pack( 58 'CC', 59 (87 + $b + ((($b - 10) >> 8) & ~38)), 60 (87 + $c + ((($c - 10) >> 8) & ~38)) 61 ); 62 } 63 return $hex; 64 } 65 66 /** 67 * Convert a binary string into a hexadecimal string without cache-timing 68 * leaks, returning uppercase letters (as per RFC 4648) 69 * 70 * @param string $binString (raw binary) 71 * @return string 72 * @throws TypeError 73 */ 74 public static function encodeUpper( 75 #[\SensitiveParameter] 76 string $binString 77 ): string { 78 $hex = ''; 79 $len = Binary::safeStrlen($binString); 80 81 for ($i = 0; $i < $len; ++$i) { 82 /** @var array<int, int> $chunk */ 83 $chunk = \unpack('C', $binString[$i]); 84 $c = $chunk[1] & 0xf; 85 $b = $chunk[1] >> 4; 86 87 $hex .= \pack( 88 'CC', 89 (55 + $b + ((($b - 10) >> 8) & ~6)), 90 (55 + $c + ((($c - 10) >> 8) & ~6)) 91 ); 92 } 93 return $hex; 94 } 95 96 /** 97 * Convert a hexadecimal string into a binary string without cache-timing 98 * leaks 99 * 100 * @param string $encodedString 101 * @param bool $strictPadding 102 * @return string (raw binary) 103 * @throws RangeException 104 */ 105 public static function decode( 106 #[\SensitiveParameter] 107 string $encodedString, 108 bool $strictPadding = false 109 ): string { 110 $hex_pos = 0; 111 $bin = ''; 112 $c_acc = 0; 113 $hex_len = Binary::safeStrlen($encodedString); 114 $state = 0; 115 if (($hex_len & 1) !== 0) { 116 if ($strictPadding) { 117 throw new RangeException( 118 'Expected an even number of hexadecimal characters' 119 ); 120 } else { 121 $encodedString = '0' . $encodedString; 122 ++$hex_len; 123 } 124 } 125 126 /** @var array<int, int> $chunk */ 127 $chunk = \unpack('C*', $encodedString); 128 while ($hex_pos < $hex_len) { 129 ++$hex_pos; 130 $c = $chunk[$hex_pos]; 131 $c_num = $c ^ 48; 132 $c_num0 = ($c_num - 10) >> 8; 133 $c_alpha = ($c & ~32) - 55; 134 $c_alpha0 = (($c_alpha - 10) ^ ($c_alpha - 16)) >> 8; 135 136 if (($c_num0 | $c_alpha0) === 0) { 137 throw new RangeException( 138 'Expected hexadecimal character' 139 ); 140 } 141 $c_val = ($c_num0 & $c_num) | ($c_alpha & $c_alpha0); 142 if ($state === 0) { 143 $c_acc = $c_val * 16; 144 } else { 145 $bin .= \pack('C', $c_acc | $c_val); 146 } 147 $state ^= 1; 148 } 149 return $bin; 150 } 151} 152