• 5 Posts
  • 23 Comments
Joined 3 years ago
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Cake day: April 5th, 2022

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  • […] the attack is an extremely expensive nation state level operation that doesn’t scale.

    About $250 at most. Quoting the linked page:

    Below is a list of equipment we used for the experiments.

    • (1) Software Defined Ratio (SDR): Ettus USRP B210 USRP, ~$2100.
    • (2) Low Noise Amplifier (LNA): Foresight Intelligence FSTRFAMP06 LNA, ~$200.
    • (3) Directional Antenna: A common outdoor Log-periodic directional antenna (LPDA), ~$15.
    • (4) A laptop, of course.

    Note that the equipment can be replaced with cheaper counterparts. For example, USRP B210 can be replaced with RTL-SDR that costs ~$30.

    To reproduce the attack: our GitHub repository provides the codes and instructions for reproducing and understanding the attack. We have prepared a ready-to-use software tool that can produce real-time reconstructions of the eavesdropped videos with EM signal input from the USRP device.










  • tavu@sopuli.xyztoPrivacy@lemmy.mlEtherpad or Cryptpad
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    9 months ago

    To be clear though: by E2EE here I mean browser-side encryption with zero-knowledge on the server side.

    Etherpad is still encrypted in transit with https; only the server can snoop.

    Cryptpad and other web-based E2EE services can still be completely compromised server-side by serving malicious code to the browser, and practically the user would never know.


  • tavu@sopuli.xyztoPrivacy@lemmy.mlEtherpad or Cryptpad
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    9 months ago

    Cryptpad:

    • Full-on google docs / office365 / libreoffice type replacement with collaboration.
    • E2EE
    • The complexity means it doesn’t work well on mobile, takes a while to load on a slow connection, more frequent bugs. (3.5 MiB page transfer)
    • Self-hosting is complicated.

    Etherpad:

    • A competent collaborative rich-text editor. Doesn’t do spreadsheets or presentations or […].
    • Not E2EE (you need to trust that the server a bit more).
    • Lightweight, works on slower connections, works alright on mobile. (1.7 MiB page transfer)
    • Self-hosting quite simple.

    PrivateBin:

    • Super-simple plain-text/markdown pastebin. No editing possible once saved.
    • E2EE
    • Very small. Works fine on slow connections and mobile. (0.2 MiB page transfer)
    • Self-hosting very simple.






  • As per the quote below, a car loses about 0.08g of tread per km.

    Compared to a car, a bike tyre is about the same diameter, 10% of the width (~20mm), 28% usable tread depth (~2mm), has 50% less wheels, and can travel 10% the distance (~10000km).

    This suggests a (very approximate) tread loss of 0.08 * 10% * 28% * 50% / 10% = ~ 0.01g per km for bicycles.

    For replacing longer car journeys less typically travelled by bicycle, rail transport is the best solution and removes the issue of tyre wear.

    Quoting [deleted] in r/theydidthemath:

    Using the same assumptions as above (215/60R16 tires, 7mm of tread loss over 100,000 km), I estimate the loss of tread by volume from each tire as follows:

    Cylinder with a diameter of 664 mm and a height of 215 mm has a volume of 74,412 cm3. Cylinder with a diameter of 664-(2x7)=650 mm and a height of 215 mm has a volume of 71,307 cm3. The volume difference between a new and worn out tire is 3105 cm3.

    Typical land to sea ratio of tires is 60-70% land, depending on the type of tire. If we go with an about average value of close to 65% tread, we get the lost rubber volume of about 2000 cm3 or 2,000,000 mm3 over a single tires lifespan.

    Each revolution of a tire loses about 0,04 mm3 of tread, which, according to Wolfram Alpha, is a bit less than the volume of a medium grain of sand.

    If we look at the entire car with 4 tires over a kilometer of road, we get 80 mm3 or about 0,08 grams of tread lost per car per kilometer.


  • Having wider tyres ~2"/50mm or so pretty much eliminates the risk (and gives a comfy ride). If you really like the speed of narrow tyres, it’s really quite safe with the right technique – crossing tracks at an angle to avoid mishaps (I find 30° is sufficient, 90° is never a problem), and when they’re slippery, treating them like ice. It becomes second nature soon enough.

    I think there are some rubber/elasromer inserts which have been developed which also eliminate the groove – it presents a flat surface to bikes, yet squishes down for the tram wheel flange under the immense weight.