Autentifikatsiyalangan shifrlash (AEAD)

function korsat(string $nom, string $qiymat): void
{
    printf("%-12s %s%s", $nom . ':', $qiymat, PHP_EOL);
}

function konvert(string $matn, string $kalit, string $nonce,
                 string $aad = ''): array
{
    $teg = '';
    $shifr = openssl_encrypt($matn, 'aes-256-gcm', $kalit,
        OPENSSL_RAW_DATA, $nonce, $teg, $aad);

    return ['shifr' => $shifr, 'teg' => $teg];
}

$kalit = hex2bin(str_repeat('a7', 32));
$nonce = hex2bin(str_repeat('01', 12));

$natija = konvert('Karta: 8600123456781234', $kalit, $nonce);

korsat('shifrmatn', bin2hex($natija['shifr']));
korsat('teg', bin2hex($natija['teg']));
korsat('shifr uz.', strlen($natija['shifr']) . ' bayt');
korsat('teg uz.', strlen($natija['teg']) . ' bayt');

// Ochish
$ochiq = openssl_decrypt($natija['shifr'], 'aes-256-gcm', $kalit,
    OPENSSL_RAW_DATA, $nonce, $natija['teg']);
korsat('ochilgan', $ochiq);

$kalit = hex2bin(str_repeat('a7', 32));
$nonce = hex2bin(str_repeat('01', 12));

$n = konvert('rol=user;id=1234', $kalit, $nonce);

// 1. Toza holat
$ochiq = openssl_decrypt($n['shifr'], 'aes-256-gcm', $kalit,
    OPENSSL_RAW_DATA, $nonce, $n['teg']);
korsat('ozgarishsiz', var_export($ochiq, true));

// 2. Shifrmatnning bir bayti o'zgartirildi
$buzuq = $n['shifr'];
$buzuq[5] = chr(ord($buzuq[5]) ^ 0x04);
korsat('shifr buzildi', var_export(openssl_decrypt($buzuq, 'aes-256-gcm',
    $kalit, OPENSSL_RAW_DATA, $nonce, $n['teg']), true));

// 3. Teg o'zgartirildi
$buzuqTeg = $n['teg'];
$buzuqTeg[0] = chr(ord($buzuqTeg[0]) ^ 0x01);
korsat('teg buzildi', var_export(openssl_decrypt($n['shifr'], 'aes-256-gcm',
    $kalit, OPENSSL_RAW_DATA, $nonce, $buzuqTeg), true));

// 4. Nonce o'zgartirildi
$buzuqNonce = hex2bin(str_repeat('02', 12));
korsat('nonce buzildi', var_export(openssl_decrypt($n['shifr'], 'aes-256-gcm',
    $kalit, OPENSSL_RAW_DATA, $buzuqNonce, $n['teg']), true));

$kalit = hex2bin(str_repeat('a7', 32));
$nonce = hex2bin(str_repeat('01', 12));

// Yozuv identifikatori ochiq qoladi, lekin AAD ga bog'lanadi
$aad = 'yozuv_id=42;jadval=kartalar';

$n = konvert('8600123456781234', $kalit, $nonce, $aad);
korsat('shifrmatn', bin2hex($n['shifr']));

// To'g'ri AAD bilan ochiladi
$ochiq = openssl_decrypt($n['shifr'], 'aes-256-gcm', $kalit,
    OPENSSL_RAW_DATA, $nonce, $n['teg'], $aad);
korsat('togri aad', var_export($ochiq, true));

// AAD o'zgartirilsa - ochilmaydi
$soxtaAad = 'yozuv_id=99;jadval=kartalar';
korsat('soxta aad', var_export(openssl_decrypt($n['shifr'], 'aes-256-gcm',
    $kalit, OPENSSL_RAW_DATA, $nonce, $n['teg'], $soxtaAad), true));

// AAD umuman berilmasa ham - ochilmaydi
korsat('aad yoq', var_export(openssl_decrypt($n['shifr'], 'aes-256-gcm',
    $kalit, OPENSSL_RAW_DATA, $nonce, $n['teg']), true));

final class Konvert
{
    private const VERSIYA = "\x01";
    private const NONCE = 12;
    private const TEG = 16;

    public function __construct(private readonly string $kalit)
    {
        if (strlen($kalit) !== 32) {
            throw new InvalidArgumentException('kalit 32 bayt bolishi kerak');
        }
    }

    public function yop(string $matn, string $aad = ''): string
    {
        $nonce = random_bytes(self::NONCE);
        $teg = '';

        $shifr = openssl_encrypt($matn, 'aes-256-gcm', $this->kalit,
            OPENSSL_RAW_DATA, $nonce, $teg, $aad);

        if ($shifr === false) {
            throw new RuntimeException('shifrlash muvaffaqiyatsiz');
        }

        return self::VERSIYA . $nonce . $teg . $shifr;
    }

    public function och(string $konvert, string $aad = ''): string
    {
        $eng = 1 + self::NONCE + self::TEG;
        if (strlen($konvert) < $eng) {
            throw new RuntimeException('konvert juda qisqa');
        }

        if ($konvert[0] !== self::VERSIYA) {
            throw new RuntimeException(
                'nomalum versiya: ' . bin2hex($konvert[0]));
        }

        $nonce = substr($konvert, 1, self::NONCE);
        $teg = substr($konvert, 1 + self::NONCE, self::TEG);
        $shifr = substr($konvert, $eng);

        $matn = openssl_decrypt($shifr, 'aes-256-gcm', $this->kalit,
            OPENSSL_RAW_DATA, $nonce, $teg, $aad);

        if ($matn === false) {
            throw new RuntimeException('butunlik tekshiruvi otmadi');
        }

        return $matn;
    }
}

$konvert = new Konvert(hex2bin(str_repeat('a7', 32)));

$yopiq = $konvert->yop('Maxfiy hisobot', 'yozuv=7');

echo 'konvert uzunligi: ', strlen($yopiq), ' bayt', PHP_EOL;
echo 'versiya bayti:    ', bin2hex($yopiq[0]), PHP_EOL;
echo 'ochilgan:         ', $konvert->och($yopiq, 'yozuv=7'), PHP_EOL;

// Har chaqiruvda yangi nonce - shifrmatn ham boshqacha
$ikkinchi = $konvert->yop('Maxfiy hisobot', 'yozuv=7');
echo 'ikki konvert bir xilmi: ',
    $yopiq === $ikkinchi ? 'ha' : 'YOQ', PHP_EOL;
echo 'ikkalasi ham ochiladi:  ',
    $konvert->och($ikkinchi, 'yozuv=7'), PHP_EOL;

$konvert = new Konvert(hex2bin(str_repeat('a7', 32)));
$yopiq = $konvert->yop('Maxfiy hisobot', 'yozuv=7');

$sinovlar = [
    'notogri aad' => static fn() => $konvert->och($yopiq, 'yozuv=8'),
    'buzilgan bayt' => static function () use ($konvert, $yopiq) {
        $b = $yopiq;
        $b[40] = chr(ord($b[40]) ^ 0xff);
        return $konvert->och($b, 'yozuv=7');
    },
    'qisqa konvert' => static fn() => $konvert->och('abc'),
    'notogri versiya' => static fn() => $konvert->och("\x09" . substr($yopiq, 1)),
    'boshqa kalit' => static function () use ($yopiq) {
        return (new Konvert(hex2bin(str_repeat('b8', 32))))->och($yopiq, 'yozuv=7');
    },
];

foreach ($sinovlar as $nom => $sinov) {
    try {
        $sinov();
        printf('%-16s OTDI - KUTILMAGAN%s', $nom, PHP_EOL);
    } catch (RuntimeException $x) {
        printf('%-16s RAD: %s%s', $nom, $x->getMessage(), PHP_EOL);
    }
}

$kalit = hex2bin(str_repeat('c3', 32));
$nonce = hex2bin(str_repeat('04', 12));
$teg = '';

$shifr = openssl_encrypt('Maxfiy xabar', 'chacha20-poly1305', $kalit,
    OPENSSL_RAW_DATA, $nonce, $teg);

korsat('shifrmatn', bin2hex($shifr));
korsat('teg', bin2hex($teg));

$ochiq = openssl_decrypt($shifr, 'chacha20-poly1305', $kalit,
    OPENSSL_RAW_DATA, $nonce, $teg);
korsat('ochilgan', $ochiq);

// Buzilgan holat
$buzuq = $shifr;
$buzuq[0] = chr(ord($buzuq[0]) ^ 0x01);
korsat('buzilgan', var_export(openssl_decrypt($buzuq, 'chacha20-poly1305',
    $kalit, OPENSSL_RAW_DATA, $nonce, $teg), true));

$kalit = hex2bin(str_repeat('a7', 32));
$nonce = hex2bin(str_repeat('01', 12));

foreach ([16, 12, 8, 4] as $uz) {
    $teg = '';
    openssl_encrypt('test', 'aes-256-gcm', $kalit,
        OPENSSL_RAW_DATA, $nonce, $teg, '', $uz);
    printf('teg %2d bayt (%3d bit): %s%s', $uz, $uz * 8,
        bin2hex($teg), PHP_EOL);
}