Knowledge check

End-to-end encrypted messaging: the Signal Protocol

10 questions testing what you just read — no login, no tracking, just immediate feedback.

Question 1 of 10

What problem does X3DH solve that plain Diffie-Hellman can't?

Question 2 of 10

What two mechanisms combine to make up the Double Ratchet algorithm?

Question 3 of 10

What is post-compromise security?

Question 4 of 10

What's the key difference between transport encryption (TLS) and end-to-end encryption (E2EE)?

Question 5 of 10

Besides Signal itself, what other widely used messaging app derives its protocol from Signal's?

Question 6 of 10

In the symmetric-key ratchet, what does each chain key produce before discarding itself?

Question 7 of 10

Why can't you walk the symmetric-key ratchet's chain backward to reconstruct earlier message keys from a later one?

Question 8 of 10

What must Bob do before Alice can compute a shared secret via X3DH, per the module's swimlane diagram?

Question 9 of 10

Does the server relaying Signal messages ever see anything secret during the X3DH exchange?

Question 10 of 10

What gives the Double Ratchet forward secrecy at the level of individual messages?

0 / 10 answered