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Re: [MSEC] The use HMAC



Hi

At 04:23 PM 6/13/2001 +0200, brakta wrote:
>Hello,
>  Mechanisms that provide such integrity check based on a secret key are
>usually called "message authentication codes" (MAC). Typically, message
>authentication codes are used between (two parties) that share a secret
>key in order to validate information transmitted between these parties.
>Can i use "message authentification codes" between more than two
>parties, i mean in multicast application, specially 1- N mode ?
>--

Yes you can with Adrian's caveat that a rogue member of the group
is able to impersonate a sender if you cannot uniquely authenticate
the sender.  And you can't uniquely authenticate the sender using
"group authentication" with a MAC.  But you can using digital
signatures, the cost of which can be amortized over many packets
using tesla or similar algorithms.

Mark

>------------------------------------------
>   Saber.BRAKTA
>   LORIA - UHP NANCY I
>   CAMPUS SCIENTIFIQUE B.P.239
>   54506 VANDOEUVRE-LES-NANCY CEDEX
>   E-mail : brakta@loria.fr
>------------------------------------------



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