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Re: "known in advance" public key authentication?
From: |
Daniel Kahn Gillmor |
Subject: |
Re: "known in advance" public key authentication? |
Date: |
Thu, 08 Nov 2012 01:44:46 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:10.0.10) Gecko/20121028 Icedove/10.0.10 |
On 11/07/2012 10:18 PM, Ivan Shmakov wrote:
> OTOH, most of the data transferred over such a channel will
> either be public (and then either self-certifying or signed) or
> already encrypted anyway. Thus, for a start, I may forget about
> authentication altogether. Unfortunately, some fraction of the
> data is likely to be at least mildly sensitive, and apart from
> that, an authenticated channel opens a possibility of a DoS.
Without robust and reliable authentication of your peer, you can have no
guarantees of confidentiality.
Put another way: if you don't know who you are talking to, you cannot
have a private conversation. You might be talking to the very person
you want to keep a secret from!
Association of a public key with a peer over an untrusted network is a
challenging problem. Simply presenting a random public key at
connection time and expecting the other peer will automatically know
it's the right one opens your application up to a MITM attack.
You seem to be leaning in the direction of an unauthenticated
connection; while that might be sufficient against an eavesdropping-only
attacker, i advise you to reconsider. On the internet, it's not a large
leap to go from an eavesdropper to a MITM :(
--dkg
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- Re: "known in advance" public key authentication?, (continued)
Re: "known in advance" public key authentication?, Ivan Shmakov, 2012/11/07
Re: "known in advance" public key authentication?, Ilari Liusvaara, 2012/11/07
Re: "known in advance" public key authentication?, Florian Weimer, 2012/11/07
Re: "known in advance" public key authentication?, Ivan Shmakov, 2012/11/07
- Re: "known in advance" public key authentication?,
Daniel Kahn Gillmor <=