Jose\Util\RSA::getRSAESOAEP PHP Méthode

    private static function getRSAESOAEP(RSAKey $key, $c, Hash $hash)
    {
        $c = self::convertOctetStringToInteger($c);
        $m = self::getRSADP($key, $c);
        Assertion::isInstanceOf($m, BigInteger::class);
        $em = self::convertIntegerToOctetString($m, $key->getModulusLength());
        $lHash = $hash->hash('');
        $maskedSeed = mb_substr($em, 1, $hash->getLength(), '8bit');
        $maskedDB = mb_substr($em, $hash->getLength() + 1, null, '8bit');
        $seedMask = self::getMGF1($maskedDB, $hash->getLength(), $hash);
        $seed = $maskedSeed ^ $seedMask;
        $dbMask = self::getMGF1($seed, $key->getModulusLength() - $hash->getLength() - 1, $hash);
        $db = $maskedDB ^ $dbMask;
        $lHash2 = mb_substr($db, 0, $hash->getLength(), '8bit');
        $m = mb_substr($db, $hash->getLength(), null, '8bit');
        Assertion::eq($lHash, $lHash2);
        $m = ltrim($m, chr(0));
        Assertion::eq(ord($m[0]), 1);
        return mb_substr($m, 1, null, '8bit');
    }