Viewing file:  MultibyteStringConverter.php (4.52 KB) -rw-r--r--
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<?php
declare(strict_types=1);
/*
* The MIT License (MIT)
*
* Copyright (c) 2014-2018 Spomky-Labs
*
* This software may be modified and distributed under the terms
* of the MIT license. See the LICENSE file for details.
*
* @link https://github.com/web-token/jwt-framework/blob/v1.2/src/Component/Core/Util/ECSignature.php
*/
namespace Lcobucci\JWT\Signer\Ecdsa;
use function assert;
use function bin2hex;
use function dechex;
use function hex2bin;
use function hexdec;
use function is_string;
use function str_pad;
use function strlen;
use function substr;
use const STR_PAD_LEFT;
/**
* ECDSA signature converter using ext-mbstring
*
* @internal
*/
final class MultibyteStringConverter implements SignatureConverter
{
private const ASN1_SEQUENCE = '30';
private const ASN1_INTEGER = '02';
private const ASN1_MAX_SINGLE_BYTE = 128;
private const ASN1_LENGTH_2BYTES = '81';
private const ASN1_BIG_INTEGER_LIMIT = '7f';
private const ASN1_NEGATIVE_INTEGER = '00';
private const BYTE_SIZE = 2;
public function toAsn1(string $points, int $length): string
{
$points = bin2hex($points);
if (self::octetLength($points) !== $length) {
throw ConversionFailed::invalidLength();
}
$pointR = self::preparePositiveInteger(substr($points, 0, $length));
$pointS = self::preparePositiveInteger(substr($points, $length, null));
$lengthR = self::octetLength($pointR);
$lengthS = self::octetLength($pointS);
$totalLength = $lengthR + $lengthS + self::BYTE_SIZE + self::BYTE_SIZE;
$lengthPrefix = $totalLength > self::ASN1_MAX_SINGLE_BYTE ? self::ASN1_LENGTH_2BYTES : '';
$asn1 = hex2bin(
self::ASN1_SEQUENCE
. $lengthPrefix . dechex($totalLength)
. self::ASN1_INTEGER . dechex($lengthR) . $pointR
. self::ASN1_INTEGER . dechex($lengthS) . $pointS,
);
assert(is_string($asn1));
assert($asn1 !== '');
return $asn1;
}
private static function octetLength(string $data): int
{
return (int) (strlen($data) / self::BYTE_SIZE);
}
private static function preparePositiveInteger(string $data): string
{
if (substr($data, 0, self::BYTE_SIZE) > self::ASN1_BIG_INTEGER_LIMIT) {
return self::ASN1_NEGATIVE_INTEGER . $data;
}
while (
substr($data, 0, self::BYTE_SIZE) === self::ASN1_NEGATIVE_INTEGER
&& substr($data, 2, self::BYTE_SIZE) <= self::ASN1_BIG_INTEGER_LIMIT
) {
$data = substr($data, 2, null);
}
return $data;
}
public function fromAsn1(string $signature, int $length): string
{
$message = bin2hex($signature);
$position = 0;
if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_SEQUENCE) {
throw ConversionFailed::incorrectStartSequence();
}
// @phpstan-ignore-next-line
if (self::readAsn1Content($message, $position, self::BYTE_SIZE) === self::ASN1_LENGTH_2BYTES) {
$position += self::BYTE_SIZE;
}
$pointR = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));
$pointS = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));
$points = hex2bin(str_pad($pointR, $length, '0', STR_PAD_LEFT) . str_pad($pointS, $length, '0', STR_PAD_LEFT));
assert(is_string($points));
assert($points !== '');
return $points;
}
private static function readAsn1Content(string $message, int &$position, int $length): string
{
$content = substr($message, $position, $length);
$position += $length;
return $content;
}
private static function readAsn1Integer(string $message, int &$position): string
{
if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_INTEGER) {
throw ConversionFailed::integerExpected();
}
$length = (int) hexdec(self::readAsn1Content($message, $position, self::BYTE_SIZE));
return self::readAsn1Content($message, $position, $length * self::BYTE_SIZE);
}
private static function retrievePositiveInteger(string $data): string
{
while (
substr($data, 0, self::BYTE_SIZE) === self::ASN1_NEGATIVE_INTEGER
&& substr($data, 2, self::BYTE_SIZE) > self::ASN1_BIG_INTEGER_LIMIT
) {
$data = substr($data, 2, null);
}
return $data;
}
}
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