[Cryptography] Auditable logs?

[Sandy Harris]

Various computer-mediated activities may end up in court for a range
of reasons and in many cases log files  will be used as evidence.
However for most log file formats, deleting a few lines or adding a
few bogus ones is trivial. Even forging an entire file or large chunk
thereof is not impossible.

Lawyers for one side or the other seem quite likely to attack the
credibility of log files and/or of the sys admin who provides them. In
at least some cases, proof "beyond reasonable doubt" is required and
that is going to be very difficult if the lawyers trying to create
some doubt are good.

What sort of crypto mechanisms might help here? I can see various
applications of digital signatures and timestamps that might help, but
noting close to a full solution.