On Sun, Dec 08, 2019 at 09:43:03AM +0000, jim bell wrote: > A few days ago, there was a news item about a bank robber who was caught > because he (stupidly) took his cell phone to the robbery. He was exposed by > the technique called "geo-fencing". > https://www.nbcnews.com/news/us-news/police-used-google-location-data-find-accused-bank-robber-he-n1086836 > The legitimacy of the use of this technique is currently a subject of his > appeal, but is not relevant to my comment, below. > Maybe if he had been smart enough to know how to activate his > phone's "airplane mode", which supposedly turns off all electronic > transmissions, he wouldn't have quite as identifiable. But, as > cypherpunks know, it isn't clear that a smartphone's promise that > it won't transmit and thus reveal its location can be relied upon. > Further, even if we can know, for sure, that a phone didn't > TRANSMIT during that relevant period, that doesn't mean that it > didn't record its path in space (by GPS) and time during such a > period, later to be uploaded to Google servers.
We know that does happen. > Perhaps wrapping > that phone in a few layers of aluminum foil would have blocked the > (already quite weak) GPS signals, so the phone wouldn't know where > it was. > However, it occurred to that there may one day be a need for a person to > enter a geographic area that has cellular phone service, but not have his > smartphone emit signals that would (immediately) identify that phone's > presence there. Okay, "airplane mode". But, he could also want his presence > to be unknown including later, by disabling Google location services. MAYBE > that would 'work'. He might want to visit like this multiple times, leaving > that area each time, not leaving an electronic trace. Yet, maybe he'd want > to use that smartphone's camera (to record video and still frame) and audio > (to record sound). > Even more, maybe an event would occur, and he would have evidence of it in > video and audio, and he might (later) want to document the fact by uploading > video and audio evidence to a server somewhere, at that time or seconds > later. But he might not want to record the video, still frames, or audio 'in > the clear'. And, there would be no reason that he'd have to upload the > entire (huge) video and audio files: He could subject the resulting data to > a 'cryptographic hash', > https://en.wikipedia.org/wiki/Cryptographic_hash_function so that he could > upload only 256 bits. That hash could itself be encrypted, and could > actually be a hash of a table of hashes: A hash for each one second of video > and/or audio, or even a smaller quantity of time, just for an example. > Initially, he could upload just the overall hash. And if, later on, he > wanted to prove that he had acquired some data at a specific time, or at > least prior to some specific time (when it was uploaded), he could do so by > releasing files which correspond to the segments of video and/or audio files, > and show that their hashes match the hashes in the uploaded hash-files. > How could he transmit that short hash back to his home base, or anywhere > else? How about > https://www.popularmechanics.com/promotions/a20777855/the-mesh/?src=syn&dom=yah&mag=pop > His release of that hash would allow him to later prove, once the source > files are released, that he had generated them, at or before a specific time > (If you believe the system to which the transmission was initially sent, or > your own computer if it's sent along quickly enough), and the video and audio > would provide evidence of the event he chooses to claim. But he might not > release the open, unhashed and unencrypted information, immediately: His > claim might be challenged, and he could hold that in reserve as evidence he > was correct. > Jim Bell > > > > https://www.popularmechanics.com/promotions/a20777855/the-mesh/?src=syn&dom=yah&mag=pop > > Or: https://gotenna.com/pages/sdk Full technical > specs:https://gotennapro.com/pages/spec-sheets#pro-pro-x-spec-sheet > True, it would be better if this was an SDR, or "software defined radio". > I just found this a couple of days ago.
