Comments on the module-file format

[Mark Reinhold]

> Date: Wed, 03 Feb 2010 17:34:10 -0500
> From: sean.mullan at sun.com

> I'm still coming up to speed on jigsaw itself, but I read through the latest
> module format and had a couple of quick comments from a security perspective.

Thanks for reading!

> - are the current hashes intended to be primarily used as a checksum or are
> they also designed as input into a subsequent signing operation? (or is that
> TBD). The hash and the data can be replaced for example, by a man-in-the-middle
> without detection.

They're intended for both purposes, though right now they're used only
for integrity checks.

> - as for the signature itself, one possible suggestion is to consider reusing
> the existing PKCS#7 format that we use for JAR signatures. PKCS#7 already
> defines a format for holding the necessary certificates and is extensible to
> support various signature algorithms. And of course there is already PKCS#7
> support in the JRE. PKCS#7 is also designed to support single-pass processing.

I'm not an expert in this area, but that makes sense to me.  Are there
other formats we should consider?  Do PGP/GPG somehow map into PKCS 7?

Where should signatures reside -- in a module file, or alongside it in a
separate file?  JAR files do the former, but some OS packaging systems
(e.g., Debian) do the latter.

If signatures go in module files then they should probably be near the
front so that certificates can be checked before reading the entire file.

- Mark