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<?php
namespace Aws\Crypto\Polyfill;
/**
* Class ByteArray
* @package Aws\Crypto\Polyfill
*/
class ByteArray extends \SplFixedArray
{
use NeedsTrait;
/**
* ByteArray constructor.
*
* @param int|string|int[] $size
* If you pass in an integer, it creates a ByteArray of that size.
* If you pass in a string or array, it converts it to an array of
* integers between 0 and 255.
* @throws \InvalidArgumentException
*/
public function __construct($size = 0)
{
$arr = null;
// Integer? This behaves just like SplFixedArray.
if (\is_array($size)) {
// Array? We need to pass the count to parent::__construct() then populate
$arr = $size;
$size = \count($arr);
} elseif (\is_string($size)) {
// We need to avoid mbstring.func_overload
if (\is_callable('\\mb_str_split')) {
$tmp = \mb_str_split($size, 1, '8bit');
} else {
$tmp = \str_split($size, 1);
}
// Let's convert each character to an 8-bit integer and store in $arr
$arr = [];
if (!empty($tmp)) {
foreach ($tmp as $t) {
if (strlen($t) < 1) {
continue;
}
$arr []= \unpack('C', $t)[1] & 0xff;
}
}
$size = \count($arr);
} elseif ($size instanceof ByteArray) {
$arr = $size->toArray();
$size = $size->count();
} elseif (!\is_int($size)) {
throw new \InvalidArgumentException(
'Argument must be an integer, string, or array of integers.'
);
}
parent::__construct($size);
if (!empty($arr)) {
// Populate this object with values from constructor argument
foreach ($arr as $i => $v) {
$this->offsetSet($i, $v);
}
} else {
// Initialize to zero.
for ($i = 0; $i < $size; ++$i) {
$this->offsetSet($i, 0);
}
}
}
/**
* Encode an integer into a byte array. 32-bit (unsigned), big endian byte order.
*
* @param int $num
* @return self
*/
public static function enc32be($num)
{
return new ByteArray(\pack('N', $num));
}
/**
* @param ByteArray $other
* @return bool
*/
public function equals(ByteArray $other)
{
if ($this->count() !== $other->count()) {
return false;
}
$d = 0;
for ($i = $this->count() - 1; $i >= 0; --$i) {
$d |= $this[$i] ^ $other[$i];
}
return $d === 0;
}
/**
* @param ByteArray $array
* @return ByteArray
*/
public function exclusiveOr(ByteArray $array)
{
self::needs(
$this->count() === $array->count(),
'Both ByteArrays must be equal size for exclusiveOr()'
);
$out = clone $this;
for ($i = 0; $i < $this->count(); ++$i) {
$out[$i] = $array[$i] ^ $out[$i];
}
return $out;
}
/**
* Returns a new ByteArray incremented by 1 (big endian byte order).
*
* @param int $increase
* @return self
*/
public function getIncremented($increase = 1)
{
$clone = clone $this;
$index = $clone->count();
while ($index > 0) {
--$index;
$tmp = ($clone[$index] + $increase) & PHP_INT_MAX;
$clone[$index] = $tmp & 0xff;
$increase = $tmp >> 8;
}
return $clone;
}
/**
* Sets a value. See SplFixedArray for more.
*
* @param int $index
* @param int $newval
* @return void
*/
public function offsetSet($index, $newval)
{
parent::offsetSet($index, $newval & 0xff);
}
/**
* Return a copy of this ByteArray, bitshifted to the right by 1.
* Used in Gmac.
*
* @return self
*/
public function rshift()
{
$out = clone $this;
for ($j = $this->count() - 1; $j > 0; --$j) {
$out[$j] = (($out[$j - 1] & 1) << 7) | ($out[$j] >> 1);
}
$out[0] >>= 1;
return $out;
}
/**
* Constant-time conditional select. This is meant to read like a ternary operator.
*
* $z = ByteArray::select(1, $x, $y); // $z is equal to $x
* $z = ByteArray::select(0, $x, $y); // $z is equal to $y
*
* @param int $select
* @param ByteArray $left
* @param ByteArray $right
* @return ByteArray
*/
public static function select($select, ByteArray $left, ByteArray $right)
{
self::needs(
$left->count() === $right->count(),
'Both ByteArrays must be equal size for select()'
);
$rightLength = $right->count();
$out = clone $right;
$mask = (-($select & 1)) & 0xff;
for ($i = 0; $i < $rightLength; $i++) {
$out[$i] = $out[$i] ^ (($left[$i] ^ $right[$i]) & $mask);
}
return $out;
}
/**
* Overwrite values of this ByteArray based on a separate ByteArray, with
* a given starting offset and length.
*
* See JavaScript's Uint8Array.set() for more information.
*
* @param ByteArray $input
* @param int $offset
* @param int|null $length
* @return self
*/
public function set(ByteArray $input, $offset = 0, $length = null)
{
self::needs(
is_int($offset) && $offset >= 0,
'Offset must be a positive integer or zero'
);
if (is_null($length)) {
$length = $input->count();
}
$i = 0; $j = $offset;
while ($i < $length && $j < $this->count()) {
$this[$j] = $input[$i];
++$i;
++$j;
}
return $this;
}
/**
* Returns a slice of this ByteArray.
*
* @param int $start
* @param null $length
* @return self
*/
public function slice($start = 0, $length = null)
{
return new ByteArray(\array_slice($this->toArray(), $start, $length));
}
/**
* Mutates the current state and sets all values to zero.
*
* @return void
*/
public function zeroize()
{
for ($i = $this->count() - 1; $i >= 0; --$i) {
$this->offsetSet($i, 0);
}
}
/**
* Converts the ByteArray to a raw binary string.
*
* @return string
*/
public function toString()
{
$count = $this->count();
if ($count === 0) {
return '';
}
$args = $this->toArray();
\array_unshift($args, \str_repeat('C', $count));
// constant-time, PHP <5.6 equivalent to pack('C*', ...$args);
return \call_user_func_array('\\pack', $args);
}
}
|
