korrents

korrents · piece

Thinking about “traceability”

Matthew Green · 1 Aug 2021 · blog.cryptographyengineering.com ↗

3 korrents from this piece

Matthew Green did not write this page.

Every claim below was made in this piece, quoted word for word and numbered in the order the piece makes them, so you can read it there rather than take our word for it. The sentence above each quote is our reading of the claim, not their wording. Each quote was checked against a stored copy of the page at build time; where the two differ, the quote is the fact.

  1. Our reading

    A tracing requirement in an encrypted messenger gives up the confidentiality of who sent what, which is the part that protects the sender.

    Their wordsIn short: traceability can really screw with the “who sent what” side of content confidentiality.
    Interesting

  2. Our reading

    Who sent what is not metadata, so an encrypted system that reveals it has given up more than the routing information it could never hide.

    Their wordsInformation revealed about “who sent what” in an E2E system is not the same as metadata.
    Interesting

  3. Our reading

    Content tracing works by turning every user into a cooperating witness, whether or not they want to cooperate with the police.

    Their wordsThis brings us to the central challenge of all content tracing proposals so far: to make tracing possible, a tracing system needs to turn every WhatsApp user (including the originator) into a cooperative green circle — regardless of whether users actually want to cooperate with police.
    Interesting