[vessenes]

Actually, knowing a 'good' (cryptographically) checksum function is equivalent to having a good encryption scheme. I believe it was Rivest who showed this, sometime in the late 1990s.

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.

[dfranke]

You can do better than that. Run the hash in HMAC mode, hash successive counter values to get a pseudorandom stream of bits. Xor your plaintext with the stream to get the ciphertext.

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.