Smalot\PdfParser\Encryption\NewFileKey::intermediateKey()

Complexity

Conditions	8
Paths	10

Size

Total Lines	61
Code Lines	34

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    function intermediateKey($password, $saltKey, $additionalKey)

It is generally recommended to explicitly declare the visibility for methods.

    {
        $hashInput = $password.$saltKey.$additionalKey;

        switch ($this->info->getRevision()) {
            case 5:
                return \hash("sha256", $hashInput, true);
                break;

break is not strictly necessary here and could be removed.

            case 6:
                /* Each round encrypts a plaintext comprising 64 copies of the
                 * input data plus the hash of the previous round, using a key
                 * and IV derived from the hash of the previous round.  Then a
                 * hash of that round's cyphertext is produced using a
                 * different hash algorithm (selected based on the cyphertext).
                 * The number of rounds is not fixed; the decision to continue
                 * is based on the cyphertext (see PDFDecryptionKey::hashContinue()).
                 * 32 bytes of the hash produced by the final round is returned.
                 */

                // initial hash
                $hash = \hash("sha256", $hashInput, true);

                $this->round = 0;

The property round does not exist. Although not strictly required by PHP, it is generally a best practice to declare properties explicitly.

                do {
                    $hashInput = $password.$hash.$additionalKey;
                    $blob = "";
                    for ($i = 0; $i < 64; ++$i) {
                        $blob .= $hashInput;
                    }
                    $key = \substr($hash, 0, 16);
                    $iv = \substr($hash, 16, 16);

                    // This is different from the key decryption algorithm
                    $this->cyphertext = \openssl_encrypt($blob, "aes-128-cbc", $key, OPENSSL_RAW_DATA | OPENSSL_NO_PADDING, $iv);

The property cyphertext does not exist. Although not strictly required by PHP, it is generally a best practice to declare properties explicitly.

                    // Derive some 64 bit numbers from the cyphertext and
                    // analyse them to determine the hash algorithm to use this
                    // round
                    $splinters = self::extractSplinters($this->cyphertext);
                    $remainder = (((((($splinters[0] % 3) << 32) | $splinters[1]) % 3) << 32) | $splinters[2]) % 3;
                    switch ($remainder) {
                        case 0:
                            $hash = \hash("sha256", $this->cyphertext, true);
                            break;

                        case 1:
                            $hash = \hash("sha384", $this->cyphertext, true);
                            break;

                        case 2:
                            $hash = \hash("sha512", $this->cyphertext, true);
                            break;
                    }
                    ++$this->round;
                } while ($this->hashContinue());

                return \substr($hash, 0, 32);
                break;

            default:
                throw new InvalidRevision("Unsupported revision in intermediateKey()");
        }