Re: [Trans] What logs are storing (was: The RFC6979 requirement in RFC6962-bis is bad)

[Andrew Ayer <[e-mail]>]

On Tue, 09 May 2017 00:54:38 +0200
Linus Nordberg <[e-mail]> wrote:

> Andrew Ayer <[e-mail]> wrote
> Mon, 8 May 2017 11:11:41 -0700:
> 
> > 3. When producing a new STH or SCT, sign it, store the signature,
> > and serve the stored signature instead of re-signing on-the-fly
> > every time the log needs to serve the STH or SCT.  Since the log
> > already needs to store information about STHs and SCTs, also
> > storing the signature should not be burdensome.
> 
> Why do logs already need to store information about SCTs?

Technically it's not required, but practically speaking logs need to
return an SCT for an existing entry when someone submits an
already-logged certificate (otherwise the log could be spammed into
oblivion).  To construct that SCT, the log needs to know the timestamp
of the existing entry.  A logical place to store the signature would be
alongside the timestamp.

> Do logs already need to store information about STHs because of the
> proposed get-sths API [0][1][2] or something else?

Even without the get-sths API, the log needs to store the timestamp of
the current STH.  That would be a logical place to store the signature.

Regards,
Andrew