3 ms·
If I get the idea right, the server keeps a list of Alice's p, g and A generated in advance for a Diffie-Hellman exchange. Bob then can complete his part of th
by pampa 13y ago
If I get the idea right, the server keeps a list of Alice's p, g and A generated in advance for a Diffie-Hellman exchange. Bob then can complete his part of the key agreement when Alice is offline and send B together with the message ciphertext. It is vulnurable to a mitm attack just like online DH, but leaking the prekeys will not compromise anything, because the are designed to be public.
- 7952 13y agoThanks. I guess that one side of the communication is always assured to be authentic and not a MITM as it is not using a pre-generated key. Reading the documentation there is a facility to verify keys [1] with QR codes or voice over the phone. That's really cool. [1] https://github.com/WhisperSystems/TextSecure/wiki/Using-TextSecure https://github.com/WhisperSystems/TextSecure/wiki/Using-Text...
- StavrosK 13y agoThis does mean that you can't use ZRTP-style short authentication strings, though, as the attacker would have a very easy time brute-forcing the SAS. You'd have to verify the entire length of the fingerprint.