Show HN: Air-gapped file encryption as self-decrypting HTML page

(cms-sfx-demo.apeleg.com)

67 points | by emurlin a day ago ago

22 comments

  • itake 28 minutes ago

    I built something similar, but mine used asymetric encryption.

    It allowed people encrypt files and then the only person that can decrypt is the person with the private key, which may or may not be the person the encrypted the file.

  • G_o_D 38 minutes ago

    Isnt use of typescript, svelte etc unnecessary. Been using a bookmarklet for decade for this purpose sharing encrypted text or files. Keep the bookmarklet hosted in git.

  • technion 5 hours ago

    I never thought I'd see a browser support list that specifically includes "Dilo" or, in the last few years, "Internet Explorer", but apparently you're comprehensive.

    I went to look for unauthenticated CBC mode like every time I see this sort of thing but it's actually GCM mode so, well consider me surprised.

  • lukan 13 hours ago

    I assume the "air gapped" part is merely indicating no internet required?

    • az226 12 hours ago

      Offline would be a better word.

  • som 12 hours ago

    A version of this that supported PKE would be cool. So you don't have to share a password in a side channel

  • thih9 2 hours ago

    Is there a scenario where this solution would be preferable to an encrypted zip archive?

    My guess is some heavily locked down systems. But perhaps there is more?

    • creatonez an hour ago

      ZIP encryption is quite flawed.

      That being said, I can see this being useful for a similar use case where encrypted ZIPs are useful. When malware testing, you sometimes want to avoid accidentally running the malware or exposing it to antivirus software until briefly before testing begins. Encrypted zips (as well as simple transformations like ROT13 or reversing the bytes in the file) can help control the moment the malware is unleashed. This HTML based tool could be useful for doing this in network sandboxed systems, with the specific property that it's testing the antivirus behavior when the file is marked as browser downloaded.

  • pwdisswordfishq an hour ago

    I never expected to find a circumstance in which this article would be relevant, but here I am.

    https://jdebp.uk/FGA/dont-use-self-decrypting-files.html

    I mean, basing this on HTML arguably mitigates the portability and vulnerability concerns, but the problem of trusting the decrypted contents still remains.

  • socketcluster 3 hours ago

    This is brilliant. Keen to try it out.

  • firefax 13 hours ago

    cool project!

    also does everyone have to enable js to vote, or did i troll too hard? (sorry!)

  • DylanMerigaud a day ago

    Self-decrypting HTML? That's an innovative approach.

    • emurlin a day ago

      Yeah, I was inspired by self-extracting archives. I wanted to share files with basically no dependencies.

      The goal was:

      1. Something that didn't require any installation (assuming a web browser)

      2. Have a single file with no network that could self-decrypt

      3. Be fully auditable

      The second point is done by having (sort of(*)) reproducible builds and embedded OpenPGP signatures.

      The first point is made by cleverly manipulating the HTML structure so that it can decrypt without breaking the PGP signature. It can even decrypt using bare openssl (which was a design goal too, though getting the exact structure right took some work and bug reports).

      The third point is accomplished by the first two, and by the source being freely available.

      (*) Depends on the OS at the moment.

      • dang 14 hours ago

        I'm going to move this description to the top and re-up the post - I hope that's ok!

    • 112233 13 hours ago

      Somebody already has copied this innovative approach and travelled to past apparently: https://acme.com/software/securepage/

  • nikhilkxmar 18 hours ago

    Cool!

  • kooi 6 hours ago

    This is great!

    Lol @ "airgapped".

  • FatalLogic a day ago
    • dang 13 hours ago

      Added above. Thanks!

    • emurlin a day ago

      Correct