Subject: Re: [P2PSIP] New I-D: draft-birkos-p2psip-security-key-refresh-00.txt

From: Konstantinos Birkos <[email-masked]>
Date: Sat, 06 Mar 2010 00:01:16 +0200

Dear Xiaofeng Qiu,

Indeed, if protection against eavesdropping from inside the overlay is 
not an issue, encryption by means of public/private key pairs is 
unnecessary. However, eavesdropping is only one of the numerous threats 
a peer-to-peer overlay may face. Overlay routing attacks and attacks on 
the structure of the overlay depend on the exploitation of knowledge 
regarding the logical topology. This knowledge is easily gained via the 
unprotected messages exchanged in P2PSIP. The interesting part is that 
in p2p networks, many challenging threats originate from peers that are 
already members of the overlay. Of  course, the security levels P2PSIP 
should provide is up to the WG. Our motivation stems from the fact that 
P2PSIP may be used in communication scenarios with strict security 
constraints (for example communication between authorities).
What is your opinion about the refreshment of the peers' certificates?

Konstantinos Birkos
University of Patras

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From: Xiaofeng Qiu <[email-masked]>
Date: Mon, 8 Mar 2010 15:23:14 -0500

Most threats do originate from peers. A malicious node can do little damage
without joining overlay.
However, any peer will know certain part of topology in its finger table.
By purposely rejoin the overlay with a different ID, A malicious peer can
get more knowledge of the whole network. Encryption will do little help to
this. Instead, security of enrollment and ID assignment is more important.
As to refreshment of certification, as long as the peer will not keep on
online for years, refresh the key pair when the peer login is secure enough
considering security of the typical algorithm such as RSA. Skype do in this
way.
Another suggestion, why not just let the peers store their own
certificaitons. So others need not to search for receiver's certification in
the overlay.

xiaofeng Qiu
MINE Lab, BUPT

2010/3/5 Konstantinos Birkos <[email-masked]>

> Dear Xiaofeng Qiu,
>
> Indeed, if protection against eavesdropping from inside the overlay is not
> an issue, encryption by means of public/private key pairs is unnecessary.
> However, eavesdropping is only one of the numerous threats a peer-to-peer
> overlay may face. Overlay routing attacks and attacks on the structure of
> the overlay depend on the exploitation of knowledge regarding the logical
> topology. This knowledge is easily gained via the unprotected messages
> exchanged in P2PSIP. The interesting part is that in p2p networks, many
> challenging threats originate from peers that are already members of the
> overlay. Of  course, the security levels P2PSIP should provide is up to the
> WG. Our motivation stems from the fact that P2PSIP may be used in
> communication scenarios with strict security constraints (for example
> communication between authorities).