Archives du mot-clé privacy

Criteria for a pretty good private messaging app

After some readings, I ended up with this (probably not exhaustive) list of criteria for synchronous messaging (chat and talk).

  1. end-to-end encryption
  2. by default
  3. for both text (e.g. OTR) and voice (e.g. ZRTP)
  4. properly done (Telegram is broken)
  5. nothing saved in clear text on the phone (Telegram is broken, bis)
  6. decentralised (to avoid legal pressures)
  7. easy install, notably proposal to use either an email or a dedicated phone number
  8. time-limited message (applocking is not a solution, since it doesn’t provide plausible deniability)
  9. spontaneous time-limited messages (which can be started and stopped in the middle of any conversation, not in a secret chat session)
  10. no upload of contacts database – “we kill people based on metadata
  11. open-source (notice that even gitian binaries only mitigate compilation attack and of course do nothing against lack of audit)
  12. independent funding
  13. metadata-poor
  14. steganographic access — only Bitcoin’s Samourai wallet’s stealth mode has this, and this is not a messaging app)

Among the various tools I checked, three stood out:

  • Signal is my favourite, but it misses 6 – decentralised (maybe), 8 – expiring messages, 9 – spontaneous expiring messages, 10 – contacts upload, 12 – independant funding (government-funded, but so are TOR and SELinux) maybe also 13 – metadata-poor and of course 14 – steganographic access
  • Ricochet is interesting but very young and lacks 3 – both text and voice, 8 – expiring messages, 9 – spontaneous expiring messages, 14 – steganographic access
  • Google Allo improves upon Signal (which is used as the encryption base) by allowing 8 – expiring messages. But except for this, it is probably a poorer solution, privacy-wise (think of 2 – by default (this could change), 6 – decentralised, 10 – contacts upload, 11 – open-source, 12 – independant funding, 13 – metadata-poor, 14 – steganographic access)

This is for synchronous messaging. For asynchronous messaging (read: email), use tutanota (metadata-poor and they will implement PGP one day but you have to trust them and you webmail-only with no export or IMAP).

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