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File: src/Base64.php

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File: src/Base64.php
Role: Class source
Content type: text/plain
Description: Class source
Class: PHP Constant Time String Encoding
Encode text without leaking context information
Author: By
Last change:
Date: 3 years ago
Size: 8,841 bytes
 

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<?php
declare(strict_types=1);
namespace
ParagonIE\ConstantTime;

/**
 * Copyright (c) 2016 - 2018 Paragon Initiative Enterprises.
 * Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * Class Base64
 * [A-Z][a-z][0-9]+/
 *
 * @package ParagonIE\ConstantTime
 */
abstract class Base64 implements EncoderInterface
{
   
/**
     * Encode into Base64
     *
     * Base64 character set "[A-Z][a-z][0-9]+/"
     *
     * @param string $src
     * @return string
     * @throws \TypeError
     */
   
public static function encode(string $src): string
   
{
        return static::
doEncode($src, true);
    }

   
/**
     * Encode into Base64, no = padding
     *
     * Base64 character set "[A-Z][a-z][0-9]+/"
     *
     * @param string $src
     * @return string
     * @throws \TypeError
     */
   
public static function encodeUnpadded(string $src): string
   
{
        return static::
doEncode($src, false);
    }

   
/**
     * @param string $src
     * @param bool $pad Include = padding?
     * @return string
     * @throws \TypeError
     */
   
protected static function doEncode(string $src, bool $pad = true): string
   
{
       
$dest = '';
       
$srcLen = Binary::safeStrlen($src);
       
// Main loop (no padding):
       
for ($i = 0; $i + 3 <= $srcLen; $i += 3) {
           
/** @var array<int, int> $chunk */
           
$chunk = \unpack('C*', Binary::safeSubstr($src, $i, 3));
           
$b0 = $chunk[1];
           
$b1 = $chunk[2];
           
$b2 = $chunk[3];

           
$dest .=
                static::
encode6Bits( $b0 >> 2 ) .
                static::
encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
                static::
encode6Bits((($b1 << 2) | ($b2 >> 6)) & 63) .
                static::
encode6Bits( $b2 & 63);
        }
       
// The last chunk, which may have padding:
       
if ($i < $srcLen) {
           
/** @var array<int, int> $chunk */
           
$chunk = \unpack('C*', Binary::safeSubstr($src, $i, $srcLen - $i));
           
$b0 = $chunk[1];
            if (
$i + 1 < $srcLen) {
               
$b1 = $chunk[2];
               
$dest .=
                    static::
encode6Bits($b0 >> 2) .
                    static::
encode6Bits((($b0 << 4) | ($b1 >> 4)) & 63) .
                    static::
encode6Bits(($b1 << 2) & 63);
                if (
$pad) {
                   
$dest .= '=';
                }
            } else {
               
$dest .=
                    static::
encode6Bits( $b0 >> 2) .
                    static::
encode6Bits(($b0 << 4) & 63);
                if (
$pad) {
                   
$dest .= '==';
                }
            }
        }
        return
$dest;
    }

   
/**
     * decode from base64 into binary
     *
     * Base64 character set "./[A-Z][a-z][0-9]"
     *
     * @param string $src
     * @param bool $strictPadding
     * @return string
     * @throws \RangeException
     * @throws \TypeError
     * @psalm-suppress RedundantCondition
     */
   
public static function decode(string $src, bool $strictPadding = false): string
   
{
       
// Remove padding
       
$srcLen = Binary::safeStrlen($src);
        if (
$srcLen === 0) {
            return
'';
        }

        if (
$strictPadding) {
            if ((
$srcLen & 3) === 0) {
                if (
$src[$srcLen - 1] === '=') {
                   
$srcLen--;
                    if (
$src[$srcLen - 1] === '=') {
                       
$srcLen--;
                    }
                }
            }
            if ((
$srcLen & 3) === 1) {
                throw new \
RangeException(
                   
'Incorrect padding'
               
);
            }
            if (
$src[$srcLen - 1] === '=') {
                throw new \
RangeException(
                   
'Incorrect padding'
               
);
            }
        } else {
           
$src = \rtrim($src, '=');
           
$srcLen = Binary::safeStrlen($src);
        }

       
$err = 0;
       
$dest = '';
       
// Main loop (no padding):
       
for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
           
/** @var array<int, int> $chunk */
           
$chunk = \unpack('C*', Binary::safeSubstr($src, $i, 4));
           
$c0 = static::decode6Bits($chunk[1]);
           
$c1 = static::decode6Bits($chunk[2]);
           
$c2 = static::decode6Bits($chunk[3]);
           
$c3 = static::decode6Bits($chunk[4]);

           
$dest .= \pack(
               
'CCC',
                (((
$c0 << 2) | ($c1 >> 4)) & 0xff),
                (((
$c1 << 4) | ($c2 >> 2)) & 0xff),
                (((
$c2 << 6) | $c3 ) & 0xff)
            );
           
$err |= ($c0 | $c1 | $c2 | $c3) >> 8;
        }
       
// The last chunk, which may have padding:
       
if ($i < $srcLen) {
           
/** @var array<int, int> $chunk */
           
$chunk = \unpack('C*', Binary::safeSubstr($src, $i, $srcLen - $i));
           
$c0 = static::decode6Bits($chunk[1]);

            if (
$i + 2 < $srcLen) {
               
$c1 = static::decode6Bits($chunk[2]);
               
$c2 = static::decode6Bits($chunk[3]);
               
$dest .= \pack(
                   
'CC',
                    (((
$c0 << 2) | ($c1 >> 4)) & 0xff),
                    (((
$c1 << 4) | ($c2 >> 2)) & 0xff)
                );
               
$err |= ($c0 | $c1 | $c2) >> 8;
            } elseif (
$i + 1 < $srcLen) {
               
$c1 = static::decode6Bits($chunk[2]);
               
$dest .= \pack(
                   
'C',
                    (((
$c0 << 2) | ($c1 >> 4)) & 0xff)
                );
               
$err |= ($c0 | $c1) >> 8;
            } elseif (
$i < $srcLen && $strictPadding) {
               
$err |= 1;
            }
        }
       
/** @var bool $check */
       
$check = ($err === 0);
        if (!
$check) {
            throw new \
RangeException(
               
'Base64::decode() only expects characters in the correct base64 alphabet'
           
);
        }
        return
$dest;
    }

   
/**
     * Uses bitwise operators instead of table-lookups to turn 6-bit integers
     * into 8-bit integers.
     *
     * Base64 character set:
     * [A-Z] [a-z] [0-9] + /
     * 0x41-0x5a, 0x61-0x7a, 0x30-0x39, 0x2b, 0x2f
     *
     * @param int $src
     * @return int
     */
   
protected static function decode6Bits(int $src): int
   
{
       
$ret = -1;

       
// if ($src > 0x40 && $src < 0x5b) $ret += $src - 0x41 + 1; // -64
       
$ret += (((0x40 - $src) & ($src - 0x5b)) >> 8) & ($src - 64);

       
// if ($src > 0x60 && $src < 0x7b) $ret += $src - 0x61 + 26 + 1; // -70
       
$ret += (((0x60 - $src) & ($src - 0x7b)) >> 8) & ($src - 70);

       
// if ($src > 0x2f && $src < 0x3a) $ret += $src - 0x30 + 52 + 1; // 5
       
$ret += (((0x2f - $src) & ($src - 0x3a)) >> 8) & ($src + 5);

       
// if ($src == 0x2b) $ret += 62 + 1;
       
$ret += (((0x2a - $src) & ($src - 0x2c)) >> 8) & 63;

       
// if ($src == 0x2f) ret += 63 + 1;
       
$ret += (((0x2e - $src) & ($src - 0x30)) >> 8) & 64;

        return
$ret;
    }

   
/**
     * Uses bitwise operators instead of table-lookups to turn 8-bit integers
     * into 6-bit integers.
     *
     * @param int $src
     * @return string
     */
   
protected static function encode6Bits(int $src): string
   
{
       
$diff = 0x41;

       
// if ($src > 25) $diff += 0x61 - 0x41 - 26; // 6
       
$diff += ((25 - $src) >> 8) & 6;

       
// if ($src > 51) $diff += 0x30 - 0x61 - 26; // -75
       
$diff -= ((51 - $src) >> 8) & 75;

       
// if ($src > 61) $diff += 0x2b - 0x30 - 10; // -15
       
$diff -= ((61 - $src) >> 8) & 15;

       
// if ($src > 62) $diff += 0x2f - 0x2b - 1; // 3
       
$diff += ((62 - $src) >> 8) & 3;

        return \
pack('C', $src + $diff);
    }
}

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