On Wed, Jun 16, 2010 at 6:08 PM, Dimitrios Apostolou <jimis@xxxxxxx> wrote: > Hey, what do you think about this way of verifying packages? > > On Tue, 15 Jun 2010, Dimitrios Apostolou wrote: >> >> On another note, an easy but maybe a bit costly way to avoid any MITM >> tampering to packages, is serve *.md5 files for every package through a >> trusted HTTPS host. Then everyone can query that single host and check if >> the package he got from a mirror is safe. >> >> Costs: A little more traffic by serving hash files to everyone plus the >> cost of the certificate from a CA. Is the income Arch receives from ads and >> schwag enough for such a simple solution? > > Let me explain it a bit more: > > Pacman downloads package-1.tar.xz from a random mirror. > It then fetches: > > https://sums.archlinux.org/exactly/the/same/path/package-1.tar.xz.sha1 > > Pacman should then know whether the connection to sums.archlinux.org was > tampered, since the certificate is signed from a CA in ca-bundle.crt. So if > the two hashes match, the package is safe (as safe as the archlinux > server...) > > That way any type of file can be verified (packages, db files, PKGBUILDs, > patches etc) provided that its cryptographic hash is in that HTTPS host. > Obviously to be able to verify db files, they need a timestamp appended to > them, e.g. core-YYYYMMDDHHMM.tar.gz. That necessary change is perhaps the > most difficult part of this proposal. > > If too many small files is a problem, maybe the whole db.tar.gz can be > served (at the cost of a higher bandwidth utilisation). > > > This solution doesn't use package signing nor a web-of-trust. It simply > piggybacks on the tried and true HTTPS mechanism. Primary advantage is the > lack of complexity which makes it easy to understand and implement. > > > What do you think? I think that someone could blow this apart. I break in, touch a package of my choosing without telling anyone, and update the checksum file. Bam- everyone's systems are fucked and the developers never knew because you didn't do anything both cryptographically secure and verifiable, you just added some indirection to the process. -Dan
