On 5/25/16, dj@deadhat.com <dj@deadhat.com> wrote:

It depends on the application. CAZAC codes for stealth canaries anyone? Cryptographic spreading codes and wide bandwidths are seen in military *radiations*.

*This*, moar liek this. Imagine noise radiator capable of making your spectrum analyzer look like /dev/urandom across the board. There's no center frequency, no clock, no freq hopping, no spreading, no observables, no off the shelf wireless hardware or reference design... it's not based on that. To any viewer, it's just noise. To you and your peers who hold, say, a shared XOR key for data and a seed for DRBG noise, it looks like data... lots of data ;-) With achievable datarate, error correction, and unjammability governed by the range of spectrum you can generate noise over. You could even mimic within existing spectra if need be. The amplifiers and radiators to cover the spectrum are hardware. Everything else is SDR. There is at least one good paper on this, particularly involving GNURadio style SDR as the enabling basis, but I forgot the magic search terms to find it again. While not the one in mind (and not necessarily from the new SDR guerrilla crowd), these are somewhat relavant... Digital Chaotic Communications https://smartech.gatech.edu/bitstream/handle/1853/34849/michaels_alan_j_2009... Synchronization in Cognitive Overlay Systems http://lib.tkk.fi/Dipl/2012/urn100685.pdf Covert Ultrawideband Random Noise papers by Jack Chuang and Ram Narayanan... https://etda.libraries.psu.edu/files/final_submissions/3142