I assume the United Kingdom will impose (as opposed to just talk about it) restrictions on crypto software that may be used within it's borders.
Me, quite the border clown (yes, I always bring a up to nine (only because I can't fit ten times 100ml plus containers into a 1000ml bag) re-sealable, see-through containers of pure tap-H2O, all of them put into a clear see-through, re-sealable plastic bag of no larger volume then 1 liter, to the airport, just to have them all individually sent through expensive-looking devices, checked for any impurities for my own safety, and only to empty all of them right after I have gotten them back from very grumpy border agents into my large mouth) and always having been a hardcore believer in the European Union and every person's unalienateable right to speak freely, privately and without any government intrusion; I would like to bring a USB thumbdrive with a few megs of
/dev/random, generated by Linux with the help of a hardware PRNG, or just some concatenated hotbits.
I assume I will be questioned about the contents of the USB thumbdrive and will, truthfully, state that the contents are just random bytes. Depending on the amount of humor (in this case, humour) of the border agent I will spend some snuggly time in a holding cell thereafter.
What means do I have to prove, mathematically and statistically, that my random bits are indeed just that – random bits? What attacks (NIST-tools, chi-squared test, …) might the border agency run against my random bytes to try to prove their non-randomness? What software might he use? What software should he use?
Disclaimer: I am in no way affiliated with any nations government except casting my vote very four or five years. I might one day have to come back to this page from my suggly holding cell. See, officer, I told you.