s/forget passphrase for/cause permanent destruction of/ , Re: Letwin wants increased penalties for refusal to decrypt

[Richard Clayton]

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In article <20020819032606.GW6644@fruitcake.demon.co.uk>, Matthew Astley
<lists-ukcrypto@fruitcake.demon.co.uk> writes

>OK, here's a here-and-now question. If you're caught digging up a CD,
>and it turns out it contains half of a one time pad (eg. message
>saying "please insert second disc" when you run it) ... how does a
>court require you to disclose the location of the other half?

The court (or indeed the police before them) would serve a RIP s49
notice on you requiring you to put it into an intelligible form. ie the
Act is not restricted to particular types of system.

>Does the RIPA change their power in this case?

the police, definitely; but courts might feel that they already have
considerable powers where information is being withheld from them

>I ask this because it seems to be a very close analogy to revealing a
>passphrase.

As passed, RIP does not start with "passphrases" or "keys", but
concentrates on "putting into an intelligible form". Keys are then
mentioned as an acceptable alternative way of doing this.

I'm surprised BTW, in all this orgy of destroying disks, that there's
been no mention of "plausible deniability". In particular one can build
systems with multiple keys where you can reveal some to the authorities
but hold some back (with the authorities having significant difficulty
in determining the number of keys present in the system). There are
filesystems and also messaging systems that work this way.

>However, if the crypto key (for data stored on a conventional but
>encrypted disc) is held only[1] in RAM, the police destroy the
>evidence for you when they take the machine away.

Consider also where keys (and/or data) are only present in add-on
devices such as cryptoprocessors. It is not practical for the police to
take an image of such devices - they will need to work with the original
device - and at the top of the range this type of system can currently
be considered to be tamper-proof.

- -- 
richard                                              Richard Clayton

They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety.         Benjamin Franklin

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