mnixry/base3050.php

## base3050.php
<?php

class BaseN
{
    protected $charset;
    protected $reverseCharset;

    public function __construct(array $charset)
    {
        $this->charset = $charset;
        $this->reverseCharset = array_flip($this->charset);

        assert(count($this->charset) == count($this->reverseCharset));
    }

    public function encode(string $input): array
    {
        $output = [];
        $base = count($this->charset);
        $input_n = array_reduce(
            unpack('C*', $input),
            function ($carry, $item) {
                return bcadd(bcmul($carry, 256), $item);
            },
            0
        );
        error_log(print_r($input_n, true));

        while ($input_n > 0) {
            $output[] = $this->charset[bcmod($input_n, $base)];
            $input_n = bcdiv($input_n, $base, 0);
        }

        return $output;
    }
}

const EMOJI_DIR = './openmoji-svg-color/';

$flag = getenv('FLAG', true) ?: 'flag{base3050_1s_4w3s0m3}';


$emojis = [];

foreach (glob(EMOJI_DIR . '*.svg') as $file) {
    $file_basename = pathinfo($file, PATHINFO_FILENAME);
    $emojis[$file_basename] = file_get_contents($file);
}

$emojiKeys = array_keys($emojis);

srand(crc32($flag));
shuffle($emojiKeys);


$emojiCharset = array_slice($emojiKeys, 0, 3050);
$base3050 = new BaseN($emojiCharset);

/**
 * <div class="emoji" alt="$char">
 *  <?= $emojis[$char] ?>
 * </div>
 */

?>
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Base3050</title>
    <style>
        .emoji svg {
            margin-top: 10px;
            height: 30px;
        }

        .emoji-container {
            display: flex;
            flex-direction: row;
            flex-wrap: wrap;
        }
    </style>
</head>

<body>
    <div class="flag">
        <h1>Your flag is:</h1>
        <p> Total <?= count($emojiCharset) ?> emojis</p>
        <div class="emoji-container">
            <?php foreach ($base3050->encode($flag) as $char) : ?>
                <div class="emoji" alt="<?= $char ?>">
                    <?= $emojis[$char] ?>
                </div>
            <?php endforeach; ?>
        </div>
    </div>
    </div>
    <hr />
    <!--input chars and output encoded emoji SVGs-->
    <form method="post">
        <input type="submit" value="Encode">
        <input type="textarea" name="input" placeholder="Try something here..." value="<?= $_POST['input'] ?? '' ?>" autocomplete="false">
    </form>
    <div class="emoji-container">
        <?php if (isset($_POST['input'])) : ?>
            <?php foreach ($base3050->encode($_POST['input']) as $char) : ?>
                <div class="emoji" alt="<?= $char ?>">
                    <?= $emojis[$char] ?>
                </div>
            <?php endforeach; ?>
        <?php endif; ?>
    </div>
</body>

</html>
	<?php

	class BaseN
	{
	protected $charset;
	protected $reverseCharset;

	public function __construct(array $charset)
	{
	$this->charset = $charset;
	$this->reverseCharset = array_flip($this->charset);

	assert(count($this->charset) == count($this->reverseCharset));
	}

	public function encode(string $input): array
	{
	$output = [];
	$base = count($this->charset);
	$input_n = array_reduce(
	unpack('C*', $input),
	function ($carry, $item) {
	return bcadd(bcmul($carry, 256), $item);
	},
	0
	);
	error_log(print_r($input_n, true));

	while ($input_n > 0) {
	$output[] = $this->charset[bcmod($input_n, $base)];
	$input_n = bcdiv($input_n, $base, 0);
	}

	return $output;
	}
	}

	const EMOJI_DIR = './openmoji-svg-color/';

	$flag = getenv('FLAG', true) ?: 'flag{base3050_1s_4w3s0m3}';


	$emojis = [];

	foreach (glob(EMOJI_DIR . '*.svg') as $file) {
	$file_basename = pathinfo($file, PATHINFO_FILENAME);
	$emojis[$file_basename] = file_get_contents($file);
	}

	$emojiKeys = array_keys($emojis);

	srand(crc32($flag));
	shuffle($emojiKeys);


	$emojiCharset = array_slice($emojiKeys, 0, 3050);
	$base3050 = new BaseN($emojiCharset);

	/**
	* <div class="emoji" alt="$char">
	* <?= $emojis[$char] ?>
	* </div>
	*/

	?>
	<!DOCTYPE html>
	<html lang="en">

	<head>
	<meta charset="UTF-8">
	<title>Base3050</title>
	<style>
	.emoji svg {
	margin-top: 10px;
	height: 30px;
	}

	.emoji-container {
	display: flex;
	flex-direction: row;
	flex-wrap: wrap;
	}
	</style>
	</head>

	<body>
	<div class="flag">
	<h1>Your flag is:</h1>
	<p> Total <?= count($emojiCharset) ?> emojis</p>
	<div class="emoji-container">
	<?php foreach ($base3050->encode($flag) as $char) : ?>
	<div class="emoji" alt="<?= $char ?>">
	<?= $emojis[$char] ?>
	</div>
	<?php endforeach; ?>
	</div>
	</div>
	</div>
	<hr />
	<!--input chars and output encoded emoji SVGs-->
	<form method="post">
	<input type="submit" value="Encode">
	<input type="textarea" name="input" placeholder="Try something here..." value="<?= $_POST['input'] ?? '' ?>" autocomplete="false">
	</form>
	<div class="emoji-container">
	<?php if (isset($_POST['input'])) : ?>
	<?php foreach ($base3050->encode($_POST['input']) as $char) : ?>
	<div class="emoji" alt="<?= $char ?>">
	<?= $emojis[$char] ?>
	</div>
	<?php endforeach; ?>
	<?php endif; ?>
	</div>
	</body>

	</html>