<?php
declare(strict_types=1);
namespace ParagonIE\ConstantTime;
use InvalidArgumentException;
use RangeException;
use TypeError;
/**
* Copyright (c) 2016 - 2022 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 $binString
* @return string
*
* @throws TypeError
*/
public static function encode(string $binString): string
{
return static::doEncode($binString, 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 $encodedString
* @param bool $strictPadding
* @return string
*
* @throws RangeException
* @throws TypeError
* @psalm-suppress RedundantCondition
*/
public static function decode(string $encodedString, bool $strictPadding = false): string
{
// Remove padding
$srcLen = Binary::safeStrlen($encodedString);
if ($srcLen === 0) {
return '';
}
if ($strictPadding) {
if (($srcLen & 3) === 0) {
if ($encodedString[$srcLen - 1] === '=') {
$srcLen--;
if ($encodedString[$srcLen - 1] === '=') {
$srcLen--;
}
}
}
if (($srcLen & 3) === 1) {
throw new RangeException(
'Incorrect padding'
);
}
if ($encodedString[$srcLen - 1] === '=') {
throw new RangeException(
'Incorrect padding'
);
}
} else {
$encodedString = \rtrim($encodedString, '=');
$srcLen = Binary::safeStrlen($encodedString);
}
$err = 0;
$dest = '';
// Main loop (no padding):
for ($i = 0; $i + 4 <= $srcLen; $i += 4) {
/** @var array<int, int> $chunk */
$chunk = \unpack('C*', Binary::safeSubstr($encodedString, $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 */
$chunk = \unpack('C*', Binary::safeSubstr($encodedString, $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 | $c2) >> 8;
if ($strictPadding) {
$err |= ($c2 << 6) & 0xff;
}
} elseif ($i + 1 < $srcLen) {
$c1 = static::decode6Bits($chunk[2]);
$dest .= \pack(
'C',
((($c0 << 2) | ($c1 >> 4)) & 0xff)
);
$err |= ($c0 | $c1) >> 8;
if ($strictPadding) {
$err |= ($c1 << 4) & 0xff;
}
} elseif ($strictPadding) {
$err |= 1;
}
}
$check = ($err === 0);
if (!$check) {
throw new RangeException(
'Base64::decode() only expects characters in the correct base64 alphabet'
);
}
return $dest;
}
/**
* @param string $encodedString
* @return string
*/
public static function decodeNoPadding(string $encodedString): string
{
$srcLen = Binary::safeStrlen($encodedString);
if ($srcLen === 0) {
return '';
}
if (($srcLen & 3) === 0) {
if ($encodedString[$srcLen - 1] === '=') {
throw new InvalidArgumentException(
"decodeNoPadding() doesn't tolerate padding"
);
}
if (($srcLen & 3) > 1) {
if ($encodedString[$srcLen - 2] === '=') {
throw new InvalidArgumentException(
"decodeNoPadding() doesn't tolerate padding"
);
}
}
}
return static::decode(
$encodedString,
true
);
}
/**
* 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);
}
}
