Manufactured One Time Pad

[Andrew Meredith]

I'm sure this subject has come up before, but I was wondering if this
proposed bill made things any different.

Lets assume LEA have decided that Alice is indeed a rep for one of our 4
friendly horsemen .. lets say Darth Drugs.

They intercept a message from her to one of her supposed equine
associates. It is encrypted. It is in fact a rather steamy love letter,
but lets not worry about that. They create a message of comparable
length arranging a shipment that they have already busted. They then
calculate the OTP that would render the (relatively) innocent
declaration of undying whatevers into this dream message. Even I could
do this.

They then present the whole thing in court. The information on the bust.
The "Fact" that Alice was intimately involved. The "Cracked" key for the
message. They could even go to the theatrical step of making Alice press
the button that magically reveals all.

Which leg does she stand on .. if any? This stuff would all be
admissible under the new powers .. wouldn't it? Previously such artifice
could be used as a circumstantial indication at best, probably not at
all.

Of course honest LEOs would not use this sort of trick, but history has
unfortunately shown that our forces of law and order are not beyond
suspicion at times.

Andy M

PS This is a trivial example in technical terms. I am wondering
   more about the result than the technical merit. Hash duplication
   or devious mathematical extraction of a new N+1 th signature from
   N innocent ones also spring to mind as possible paths to the same
   court case.