crypto stamping scanned documents/WP files and court?

[Peter Sommer]

MD5 or similar hashing is routinely used in forensic disk imaging to show 
that a clone of a disk is accurate;  hashing is also routinely used to 
demonstrate that two paedophile pictures are identical (indeed it is 
regarded as a powerful intelligence and investigatory tool).  BS document 
PD008 is also widely used in document imaging storage systems (as when 
banks store images of cheques, mortgage documents etc and later want to be 
able to get the courts to accept them even where the original is no longer 
available) - indeed I was part of a team that helped APACS define its 
standards in this area.  But PD0008 is also about procedures as well as 
technology.

When you ask about the view the Courts might take - the answer is that all 
these matters are usually issues for the finding of fact, rather than areas 
where if you follow a particular procedure the courts are compelled to 
accept the result.  But I would expect MD5 etc hashing,  properly 
deployed,  to have very strong probative value.





At 13:38 06/11/2002 +0000, Adian Midgely wrote  wrote:
>My impression is that if someone shows me a file which is an image of a
>letter, scanned in or is a plain word processor file, database file or
>whatever, and shows me the MD5 digest or SHA hash or some similar result of a
>one way crypto function of it in its current state (I mean lets me derive it
>from a copy) and demonstrtates that  the copy of the file that was deposited
>in the safe of their solicitor (or similar) on a given date 6 months ago
>gives the same MD5 digest/hash ...
>
>But are the Courts inclined to come to the same view of it?
>
>

Peter Sommer
hcorn@cix.co.uk; P.M.Sommer@lse.ac.uk
Academic URL: http://csrc.lse.ac.uk//Sommer.htm
Commercial URL: http://www.pmsommer.com