141 reputation
4
bio website n8gray.org
location San Diego, CA
age
visits member for 1 year, 10 months
seen Jun 29 '12 at 18:19

Aug
13
awarded  Self-Learner
Jun
28
awarded  Teacher
Jun
28
answered Secure device pairing protocol
Jun
28
comment Secure device pairing protocol
That's exactly why I asked the question here -- to learn about existing approaches instead of trying to roll my own. Thankfully your answer and some other research has led me to investigate EKE, which looks like a pretty solid solution.
Jun
28
comment Secure device pairing protocol
Ah, I see. I thought you were saying to encrypt the string "connected" with a key based on the challenge and PIN. (It's hard to understand textual protocol descriptions.)This looks similar to EKE but without using Diffie-Hellman key exchange. One disadvantage here is that if an attacker records the traffic and somehow gets access to the PIN later they can decrypt the entire conversation.
Jun
28
awarded  Editor
Jun
28
revised Secure device pairing protocol
Asked about DH key exchange.
Jun
28
comment Secure device pairing protocol
Thanks for the reply. Maybe I'm misunderstanding, but can't you do an offline attack against the PIN based on the message in step 3? The derived key looks like Hash(Challenge + PIN), you know the challenge, and the PIN is fairly short. Just brute force until you decrypt the message and you've found the PIN.
Jun
28
awarded  Student
Jun
28
asked Secure device pairing protocol