4 ms·
We need encryption for Power over Wi-Fi or else my neighbors will steal my electricity.
by Eduard 11y ago
We need encryption for Power over Wi-Fi or else my neighbors will steal my electricity.
- livingparadox 11y agoThey can't "steal" your electricity. The output from the Wi-Fi is constant, and range limited. If they are getting any power from your signal, its power that you'd be casting off outside your house anyways. Net change in power would be 0.
- darkmighty 11y agoWell they can "steal" a tiny amount. Wi-Fi signals reflect all over, and by having a large antenna (even beyond your house/room), it absorbs some signals which might reflect/scatter back. Negligible in practice.
- njharman 11y agoBut, terrorists!
- lnanek2 11y agoTechnically, if you have the WiFi password you can have a modern luxury router beam form more signal to you than otherwise. Although my router has multiple 5GHz radios and one 2.4GHz, so it will just move me over to another radio if only one person is leeching. More clients does probably keep more radios on, using more power as well, since otherwise the router can probably sleep more hardware more often. Sort of like a Bluetooth device being discoverable keeps the radio on more, then making it connectable makes it keep the radio on more, etc..
- livingparadox 11y agoDid not know this was a thing... Is that a common ability in a router?
- projct 11y agomany 802.11ac devices can do beam forming http://www.pcworld.com/article/2061907/all-about-beamforming-the-faster-wi-fi-you-didnt-know-you-needed.html http://www.pcworld.com/article/2061907/all-about-beamforming...
- darkmighty 11y agoI see you're joking, but I believe it's theoretically possible to extract more power from a pseudorandom stream if you can predict it (that is, if you have a key to decrypt) under certain conditions. It's related to Maxwell's demon: if the signal were exciting a large rod, a flat low energy spectrum would roughly correspond to small thermal fluctuations of the rod, which are bounded by some Carnot-like efficiency. If you can perfectly predict the fluctuations though, you can set up a system of oscillating rods coupled additively to it to absorb it's power such that their sum approximates the Fourier spectrum of the rod. This allows you to extract work from the rod as if it were a sinusoidal signal, which does not have to obey the Carnot limit. In practice this effect should be small though (for the case of Wi-Fi power).
- jacquesm 11y agoThat's super interesting, thank you for this comment.
- darkmighty 11y agoWell thanks for the compliment. But note that thermodynamics is a delicate subject, that was too simple an argument to be exact. I'm still planning to figure out the details of this kind of problem myself. From my light reading it seems the theories for this subject were fully developed only recently actually, namely non-equilibrium thermodynamics and information-theoretic thermodynamics. What I mentioned is a natural extension of information-theoretic arguments to computational hardness assumptions; they're the same assumptions that allow safe encryption methods in spite of them being 'broken' in an information-theoretic sense (which doesn't consider computer limitations). Without those limitations only variants of the one-time pad are secure and public key crypto (which relies on integer factorization hardness) is impossible. Some basic readings if you're interested: https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progress https://en.wikipedia.org/wiki/Maxwell%27s_demon#Recent_progr... https://en.wikipedia.org/wiki/Computational_hardness_assumption https://en.wikipedia.org/wiki/Computational_hardness_assumpt...
- ProZsolt 11y agoYou could use Electricity over IP https://www.ietf.org/rfc/rfc3251.txt https://www.ietf.org/rfc/rfc3251.txt
- HeyLaughingBoy 11y agoThank you for this!!! I assumed you meant PoE, but just the first paragraph of that document was fkn hilarious. I needed the laugh.