RE: [logs] "Temperproof" logfiles?

rgerhardsat_private

I agree that checksums are not necessarily needed (and not necessarily
helpful). Just have a look at the list archives, and you'll see some
great discussions on this topic which provide great insight.

However, I believe that checksums will probably *add* to the credibility
of the data ... just one step further. But nothing more and - in my
point of view - definitely not vital.

Rainer

> -----Original Message-----
> From: Jason Haar [mailto:Jason.Haarat_private] 
> Sent: Friday, April 04, 2003 6:49 AM
> To: Log Analysis List
> Subject: Re: [logs] "Temperproof" logfiles?
> 
> 
> On Thu, Apr 03, 2003 at 04:04:43PM -0500, Blaise St-Laurent wrote:
> > the more i think about it though, the less i think that database +
> > tamper resistance is going to be an syslog issue. If you 
> want to sign 
> > or at least put a checksum against every line that goes 
> into your db, 
> > the best way i could think of doing this is to write a trigger on 
> > insert that calculates the checksum based on the values you supply 
> > (time, server, msg etc..) and adds it to the appropriate 
> column. I'm 
> 
> I may be showing my ignorance here, but can someone explain 
> to me how checksums *by themselves* actually "prove" the data 
> hasn't been tampered with? 
> 
> I mean, if I have a years worth of syslog data, md5 checksum 
> the files, and burn them all off onto tape. A year later in 
> court, I can confidently say that the syslog data *as it is 
> on the tape* is as valid today as it was *when the tape was 
> written* (as the checksum will hopefully match).
> 
> I mean, as far as legal goes, surely all that this 
> checksumming does it "prove" the data hasn't been altered 
> *since it was written*. It doesn't say anything about me 
> fiddling with it before I checksumed it...
> 
> Surely in court, it's simply about proving your copy of the 
> data hasn't been altered since it was written, and then it's 
> *totally* a "reliability of the witness" type problem after that...?
> 
> Similarly, if you have some nice proprietary "logging server" 
> that can take input from syslog clients and it puts it into a 
> checksummed database you can't fiddle with as you don't know 
> how it works, then you can still input bogus data can't you... 
> 
> I don't understand why this issue is always shown off as 
> being a technical issue, when it court is usually ends up 
> being a "people issue" (i.e. do they trust you)?
> 
> -- 
> Cheers
> 
> Jason Haar
> Information Security Manager, Trimble Navigation Ltd.
> Phone: +64 3 9635 377 Fax: +64 3 9635 417
> PGP Fingerprint: 7A2E 0407 C9A6 CAF6 2B9F 8422 C063 5EBB FE1D 
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