[tor-talk] secure and simple network time (hack)

[Maxim Kammerer]

On Mon, Feb 20, 2012 at 22:30, Jacob Appelbaum <jacob at appelbaum.net> wrote:
> Some people have taken to setting clocks with HTTP headers but I think that's a nightmare - not only
> because people will parse the header with questionable code but also because of latency, amongst other things.

What questionable code? HTTP Date: header is standard (RFC 1123).
HTPDate (C version) [1] does a rather good job of maintaining time
from such headers, and with an obvious header parsing vulnerability
fix and some improvements / feature additions [2] it is used in
Liberté Linux without issues. The only downside is lack of https
support.

[1] http://www.clevervest.com/htp/
[2] https://github.com/mkdesu/liberte/blob/master/src/usr/local/portage/net-misc/htpdate/files/htpdate-1.0.4-robustness.patch

> Currently tlsdate only has one way to verify certificates to ensure that
> the connection is secure - namely, it's the usual CA racket.

Does it mean that verification will fail if the clock is several years
behind, for instance?

> I'd love some code review but also just some feedback.

Does become_nobody() drop group privileges as well? Is operation over
Tor supported (I don't see any proxy handling)?

-- 
Maxim Kammerer
Liberté Linux (discussion / support: http://dee.su/liberte-contribute)