failure to explain meaning of conversation (Re: US Plans for Decryption Orders)

[adam@cypherspace.org]

Brian writes:
> We will all 'draw the line' at different places - some will not want to see
> even a an 'obligation to decrypt' but I feel that this is something that
> will benefit law enforcement without placing an unreasonable obligation on
> individuals.  Giving up keys, however, is too great an infringement of the
> rights of individuals for my liking.

I am one of those some that view 'an obligation to decrypt' as a
dangerous shift in the balance of power towards the state.

I think it is an infringment of the right to silence.  (We still
retain the right to silence though it has been somewhat reduced since
the decision to allow the fact that someone has remained silent to be
used against them.  I think this revision was a large step backwards.
This change in law reduces the meaning of innocent until proven
guilty.)

Cockney slang was I understand was used to communicate without the
police being able to understand the communciation.  The police had no
especial power to demand that the user of cockney slang explain what a
conversation meant, with a penalty of going to jail for 'failure to
explain meaning of conversation'.

Applying computers to obscuring the meaning of communications as is
typical with applying computers to other areas means that the process
has been made more efficient.

So I think the argument should still be that there should be no jail
penalty for 'failure to explain meaning of conversation'.  The police
get what they have historically be entitled to with court authorised
phone tap -- the fact that they can not understand it is their
problem.

They should just write it off as one of the rare technology shifts
which has increased privacy.

Soon enough other technologies will eat into this privacy: software
viruses to ferret keys away, increasingly miniaturised and ever more
cheaply deployed physical bugs to eavesdrop etc.

Others have given other examples of how one is not obliged to explain
the meaning of a conversation.

Examples are the eavesdropper lacking context, not comprehending in
jokes, not recognising nicknames, slang, etc.

You have no obligation to explain context, the joke, the real people
behind the nicknames, or slang.

With crypto the key is the more efficient implementation of the
'context'.


Perhaps the solution to highlight this problem is to produce the
mental analogue of Bruce Schneier's SOLITAIRE cipher [1]: a cipher
which it can be learned to be computed with mental arithmetic or word
manipulations or associations, and yet which remains secure enough for
the purpose, preferably easy enough to learn that a person could
compute it in real time.

Perhaps a tall order, and something to defer for when 'coprocessors'
or embedded computing devices with direct neural interfaces become
feasible.

Would an embedded computing device with direct neural interface be
subject to police search?  I would hope not any more than a probe of
the brain to extract information where such techniques to become
feasible.

I think the notion that police can demand decryption or keys is
heading down the path to set precedents which would tend to be
naturally transferred onto the neural implant scenario, or ability to
mechanically read information from a brain scenario with a very
undesirable outcome: police right to probe a persons brain for
information were this to become possible.

Adam

[1] SOLITAIRE is a cipher which is executed with a standard pack of
playing cards.  Schneier designed it for the Neal Stephenson's book
Cryptonomicon (www.cryptonomicon.com), though it is intended to be a
strong cipher if used correctly.  The ciphers state is the state of
the pack, and the key can be a chosen starting state of the pack, or a
chosen set of instructions coded in a word to shuffle the pack
according to an deterministic shuffling algorithm.  Encryption and
decryption are again performed using deterministic shuffling
algorithms, and ciphertext and plain text are formed by reading off
cards as letters.