[1] Each base pair encodes two bits, as DNA and RNA is basically a base-four sequence (when we're thinking about it as data storage).
Using the regulation machinery might be an interesting way to decrypt messages, if it were sufficiently complex a signalling pathway...
He suggested, for instance, blasting out a sequence of bits; if a block checksums to a certain number or matches a function, it has 'your' bits. An observer of the stream would see a bunch of random data. You would see: garbage-garbage-bits-garbage-garbage-garbage-garbage-bits-bits, etc.
This principle could work well in the system they describe.
But how does biology contribute to any of this? At best, they've taken a known cryptographic algorithm and figured out how to implement it with the computation done in wetware. At worst, and I suspect the worst, they've simply observed that some parameters of their encoding scheme are tunable, and claiming that you have a secure cryptosystem if you keep those parameters secret.
There are two problems with bacterial data storage. The first is information retrieval. Running a sequencer is no fun.
The second problem is genetic recombination, which is what they are using to 'achieve encryption'.
http://en.wikipedia.org/wiki/Genetic_recombination
Of course, there's going to be some toxic DNA sitting in the sequences they are making, and it will be to the advantage of the bacteria to spit it out, they will find a way to do it with recombinases, even the ones with the most pernicious recombinase (recA) knocked out.
Very exciting things coming as we get the protein expression laws down well. I can't wait to use http://mrgene.com to sequence DNA and a BioBrick Assembly kit to put it all together.
Obligatory awful youtube video that does a bad job of explaining Gibson Assembly:
Did you do iGEM? Back in the day I started the iGEM team at Brown. We couldn't scum a PCR machine off anyone so we spent the summer doing minipreps. A few weeks before the jamboree, we refined our models a bit and showed that the parameter space in which our project would function was so narrow that it would probably never work. Oops!
