RCT Classic encryption

.gitignore

/vendor/

composer.json

{
    "require": {
        "mdurrant/php-binary-reader": "^1.0",
        "symfony/var-dumper": "^5.0"
    }
}

composer.lock

{
    "_readme": [
        "This file locks the dependencies of your project to a known state",
        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
        "This file is @generated automatically"
    ],
    "content-hash": "89a6b4172fa21ba1812ba1840708f8d8",
    "packages": [
        {
            "name": "mdurrant/php-binary-reader",
            "version": "1.0.9",
            "source": {
                "type": "git",
                "url": "https://github.com/mdurrant/php-binary-reader.git",
                "reference": "9abf18d7b361d0ae1cd80fc6782e59b313586db6"
            },
            "dist": {
                "type": "zip",
                "url": "https://api.github.com/repos/mdurrant/php-binary-reader/zipball/9abf18d7b361d0ae1cd80fc6782e59b313586db6",
                "reference": "9abf18d7b361d0ae1cd80fc6782e59b313586db6",
                "shasum": ""
            },
            "require": {
                "php": ">=5.4"
            },
            "require-dev": {
                "phpunit/phpunit": "~4.0",
                "squizlabs/php_codesniffer": "~1.0"
            },
            "type": "library",
            "extra": {
                "branch-alias": {
                    "dev-master": "1.0.x-dev"
                }
            },
            "autoload": {
                "psr-4": {
                    "PhpBinaryReader\\": [
                        "src/",
                        "test/"
                    ]
                }
            },
            "notification-url": "https://packagist.org/downloads/",
            "license": [
                "MIT"
            ],
            "authors": [
                {
                    "name": "Matt Durrant",
                    "email": "[email protected]"
                }
            ],
            "description": "Lightweight binary reader for PHP",
            "time": "2016-12-08T01:24:19+00:00"
        },
        {
            "name": "symfony/polyfill-mbstring",
            "version": "v1.15.0",
            "source": {
                "type": "git",
                "url": "https://github.com/symfony/polyfill-mbstring.git",
                "reference": "81ffd3a9c6d707be22e3012b827de1c9775fc5ac"
            },
            "dist": {
                "type": "zip",
                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/81ffd3a9c6d707be22e3012b827de1c9775fc5ac",
                "reference": "81ffd3a9c6d707be22e3012b827de1c9775fc5ac",
                "shasum": ""
            },
            "require": {
                "php": ">=5.3.3"
            },
            "suggest": {
                "ext-mbstring": "For best performance"
            },
            "type": "library",
            "extra": {
                "branch-alias": {
                    "dev-master": "1.15-dev"
                }
            },
            "autoload": {
                "psr-4": {
                    "Symfony\\Polyfill\\Mbstring\\": ""
                },
                "files": [
                    "bootstrap.php"
                ]
            },
            "notification-url": "https://packagist.org/downloads/",
            "license": [
                "MIT"
            ],
            "authors": [
                {
                    "name": "Nicolas Grekas",
                    "email": "[email protected]"
                },
                {
                    "name": "Symfony Community",
                    "homepage": "https://symfony.com/contributors"
                }
            ],
            "description": "Symfony polyfill for the Mbstring extension",
            "homepage": "https://symfony.com",
            "keywords": [
                "compatibility",
                "mbstring",
                "polyfill",
                "portable",
                "shim"
            ],
            "time": "2020-03-09T19:04:49+00:00"
        },
        {
            "name": "symfony/var-dumper",
            "version": "v5.0.8",
            "source": {
                "type": "git",
                "url": "https://github.com/symfony/var-dumper.git",
                "reference": "09de28632f16f81058a85fcf318397218272a07b"
            },
            "dist": {
                "type": "zip",
                "url": "https://api.github.com/repos/symfony/var-dumper/zipball/09de28632f16f81058a85fcf318397218272a07b",
                "reference": "09de28632f16f81058a85fcf318397218272a07b",
                "shasum": ""
            },
            "require": {
                "php": "^7.2.5",
                "symfony/polyfill-mbstring": "~1.0"
            },
            "conflict": {
                "phpunit/phpunit": "<5.4.3",
                "symfony/console": "<4.4"
            },
            "require-dev": {
                "ext-iconv": "*",
                "symfony/console": "^4.4|^5.0",
                "symfony/process": "^4.4|^5.0",
                "twig/twig": "^2.4|^3.0"
            },
            "suggest": {
                "ext-iconv": "To convert non-UTF-8 strings to UTF-8 (or symfony/polyfill-iconv in case ext-iconv cannot be used).",
                "ext-intl": "To show region name in time zone dump",
                "symfony/console": "To use the ServerDumpCommand and/or the bin/var-dump-server script"
            },
            "bin": [
                "Resources/bin/var-dump-server"
            ],
            "type": "library",
            "extra": {
                "branch-alias": {
                    "dev-master": "5.0-dev"
                }
            },
            "autoload": {
                "files": [
                    "Resources/functions/dump.php"
                ],
                "psr-4": {
                    "Symfony\\Component\\VarDumper\\": ""
                },
                "exclude-from-classmap": [
                    "/Tests/"
                ]
            },
            "notification-url": "https://packagist.org/downloads/",
            "license": [
                "MIT"
            ],
            "authors": [
                {
                    "name": "Nicolas Grekas",
                    "email": "[email protected]"
                },
                {
                    "name": "Symfony Community",
                    "homepage": "https://symfony.com/contributors"
                }
            ],
            "description": "Symfony mechanism for exploring and dumping PHP variables",
            "homepage": "https://symfony.com",
            "keywords": [
                "debug",
                "dump"
            ],
            "time": "2020-04-12T16:45:47+00:00"
        }
    ],
    "packages-dev": [],
    "aliases": [],
    "minimum-stability": "stable",
    "stability-flags": [],
    "prefer-stable": false,
    "prefer-lowest": false,
    "platform": [],
    "platform-dev": []
}

index.php

<?php


require 'vendor/autoload.php';

$path = $argv[1];
$file = basename($path);

function rol32($value, $steps)
{
    return (($value << $steps) | ($value >> (32 - $steps))) & 0xFFFFFFFF;
}

function unapplyMask($mask, \PhpBinaryReader\BinaryReader $br, $size)
{
    $r10 = strlen($mask);
    $ecx = 0; // offset into file?
    $eax = $ecx * 7;
    $edi = $ecx * 3;


    $out = '';
    for ($i = 0; $i < $size; $i++) {
        $ecx = $eax % $r10;
        $edi = $edi % $r10;
        $eax = ($ecx + 1) % $r10;

        $dl = $br->readUInt8();
        $dl -= ord($mask[$eax]);
        $dl = u8($dl);

        $dl = $dl ^ ord($mask[$edi]);
        $dl = ($dl + ord($mask[$ecx])) & 0xFF;

        $out .= chr($dl);
        $edi += 3;
        $eax = $ecx + 7;
    }


    return $out;

}

/**
 * @param $dl
 * @return mixed
 */
function u8($dl)
{
    if ($dl < 0) {
        $packed = pack('c', $dl);
        $unpacked = unpack('C', $packed);
        $dl = $unpacked[1];
    }
    return $dl;
}

class Memory
{
    private $var_18;
    private $var_1C;

    public function seed($esi, $edx)
    {
        if ($esi == 0) {
            $this->var_18 = $edx;
        } else if ($esi === 1) {
            $this->var_1C = $edx;
        }
    }

    public function randomFillMemory($size)
    {
        $buffer = '';
        $r8d = 0xF7654321;

        $edx = $size;

        while ($edx > 0) {
            $ecx = $this->var_1C ^ $r8d;

            $r10d = $this->var_18;
            $ecx = rol32($ecx, 25);
            $ecx = ($ecx + $r10d) & 0xFFFFFFFF;

            $this->var_18 = $ecx;

            $r9d = $r10d >> 3;

            $ecx = rol32($r10d, 29);
            $this->var_1C = $ecx;

            $buffer .= chr($r9d & 0xFF);

            if ($edx < 2) break;
            $buffer .= chr(($r10d >> 11) & 0xFF);

            if ($edx < 3) break;
            $buffer .= chr(($r10d >> 19) & 0xFF);


            if ($edx < 4) break;
            $buffer .= chr(($ecx >> 24) & 0xFF);

            $edx -= 4;
        }

        return $buffer;
    }
}

$edx = 0;

$rev = strrev($file);
$rev = str_split($rev, 1);
foreach ($rev as $char) {
    $cl = ord($char);
    $esi = ($edx << 5) & 0xFFFFFFFF;
    $edx = (($edx + $esi) & 0xFFFFFFFF) ^ $cl;
}

$ebx = 0;
$fwd = str_split($file, 1);
foreach ($fwd as $char) {
    $cl = ord($char);
    $ecx = ($ebx << 5) & 0xFFFFFFFF;
    $ebx = (($ebx + $ecx) & 0xFFFFFFFF) ^ $cl;
}

$memory = new Memory();
$memory->seed(0, $edx);
$memory->seed(1, $ebx);

$buffer = $memory->randomFillMemory(0x1000);
$brMask = new \PhpBinaryReader\BinaryReader($buffer);

$br = new \PhpBinaryReader\BinaryReader(fopen($path, 'rb'));

$out = unapplyMask($buffer, $br, $br->getEofPosition() - 4);
// Last 4 bytes are a checksum?

file_put_contents(basename($path, '.sea') . '.sc6', $out);

Is this going to get upstreamed?

Not by me at least. Feel free to implement it in C++.