Merge "APK Signature Scheme v3: add version number to proof-of-rotation."

        List<Integer> flagsList = new ArrayList<>();

        // Proof-of-rotation struct:

        // is basically a singly linked list of nodes, called levels here, each of which have the

        // following structure:

        // A uint32 version code followed by basically a singly linked list of nodes, called levels

        // here, each of which have the following structure:

        // * length-prefix for the entire level

        //     - length-prefixed signed data (if previous level exists)

        //         * length-prefixed X509 Certificate

        //     - length-prefixed signature over the signed data in this level.  The signature here

        //         is verified using the certificate from the previous level.

        // The linking is provided by the certificate of each level signing the one of the next.

        try {

            // get the version code, but don't do anything with it: creator knew about all our flags

            porBuf.getInt();

            while (porBuf.hasRemaining()) {

                levelCount++;

            try {

                ByteBuffer level = getLengthPrefixedSlice(porBuf);

                ByteBuffer signedData = getLengthPrefixedSlice(level);

                int flags = level.getInt();

                lastSigAlgorithm = sigAlgorithm;

                certs.add(lastCert);

                flagsList.add(flags);

            }

        } catch (IOException | BufferUnderflowException e) {

            throw new IOException("Failed to parse Proof-of-rotation record", e);

        } catch (NoSuchAlgorithmException | InvalidKeyException

            throw new SecurityException("Failed to decode certificate #" + levelCount

                    + " when verifying Proof-of-rotation record", e);

        }

        }

        return new VerifiedProofOfRotation(certs, flagsList);

    }