Jose\Component\Core\Util\ECSignature

Complexity

Total Complexity

15

Size/Duplication

Total Lines	97
Duplicated Lines	0 %

Coupling/Cohesion

Components	0
Dependencies	0

Importance

Changes

0

4 Methods

Rating	Name	Duplication	Size	Complexity
A	toDER()	0	21	3
B	fromDER()	0	29	5
A	preparePositiveInteger()	0	11	4
A	retrievePositiveInteger()	0	8	3

<?php

declare(strict_types=1);

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2014-2017 Spomky-Labs
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

namespace Jose\Component\Core\Util;

/**
 * Class ECSignature.
 */
final class ECSignature
{
    /**
     * @param string $signature
     * @param int    $partLength
     *
     * @return string
     */
    public static function toDER(string $signature, int $partLength): string
    {
        $signature = unpack('H*', $signature)[1];
        if (mb_strlen($signature, '8bit') !== 2 * $partLength) {
            throw new \InvalidArgumentException('Invalid length.');
        }
        $R = mb_substr($signature, 0, $partLength, '8bit');
        $S = mb_substr($signature, $partLength, null, '8bit');

        $R = self::preparePositiveInteger($R);
        $Rl = mb_strlen($R, '8bit')/2;
        $S = self::preparePositiveInteger($S);
        $Sl = mb_strlen($S, '8bit')/2;
        $der = pack('H*',
            '30'. ($Rl+$Sl+4 > 128 ? '81' : '').dechex($Rl+$Sl+4)
            .'02'.dechex($Rl).$R
            .'02'.dechex($Sl).$S
        );

        return $der;
    }

    /**
     * @param string $der
     * @param int    $partLength
     *
     * @return string
     */
    public static function fromDER(string $der, int $partLength): string
    {
        $hex = unpack('H*', $der)[1];
        if ('30' !== mb_substr($hex, 0, 2, '8bit')) { // SEQUENCE
            throw new \RuntimeException();
        }
        if ('81' === mb_substr($hex, 2, 2, '8bit')) { // LENGTH > 128
            $hex = mb_substr($hex, 6, null, '8bit');
        } else {
            $hex = mb_substr($hex, 4, null, '8bit');
        }
        if ('02' !== mb_substr($hex, 0, 2, '8bit')) { // INTEGER
            throw new \RuntimeException();
        }

        $Rl = hexdec(mb_substr($hex, 2, 2, '8bit'));
        $R = self::retrievePositiveInteger(mb_substr($hex, 4, $Rl*2, '8bit'));
        $R = str_pad($R, $partLength, '0', STR_PAD_LEFT);

        $hex = mb_substr($hex, 4+$Rl*2, null, '8bit');
        if ('02' !== mb_substr($hex, 0, 2, '8bit')) { // INTEGER
            throw new \RuntimeException();
        }
        $Sl = hexdec(mb_substr($hex, 2, 2, '8bit'));
        $S = self::retrievePositiveInteger(mb_substr($hex, 4, $Sl*2, '8bit'));
        $S = str_pad($S, $partLength, '0', STR_PAD_LEFT);

        return pack('H*', $R.$S);
    }

    /**
     * @param string $data
     *
     * @return string
     */
    private static function preparePositiveInteger(string $data): string
    {
        if (mb_substr($data, 0, 2, '8bit') >= '7f') {
            return '00'.$data;
        }
        while ('00' === mb_substr($data, 0, 2, '8bit') && mb_substr($data, 2, 2, '8bit') < '7f') {
            $data = mb_substr($data, 2, null, '8bit');
        }

        return $data;
    }

    /**
     * @param string $data
     *
     * @return string
     */
    private static function retrievePositiveInteger(string $data): string
    {
        while ('00' === mb_substr($data, 0, 2, '8bit') && mb_substr($data, 2, 2, '8bit') > '7f') {
            $data = mb_substr($data, 2, null, '8bit');
        }

        return $data;
    }
}