Re: Authentication of a messages using a counter and a MAC



On 25 Jan, 02:07, "Joseph Ashwood" <ashw...@xxxxxxx> wrote:
"Jakob" <jakobsson....@xxxxxxxxx> wrote in messagenews:1169645124.922789.249050@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Hi!
Where I can find information about it this approach?
We have a messages, 128 bit key, counter, AES, and OMAC and want to
authenticate a stream of messages using

MAC (key)[counter|| message]
how to do it?Include the MAC in the transmitted message, the other side computes MAC
(key)[counter||message] compare the two values, if they match it's
authenticated.
Joe

So is this OK?
Two nodes share a symmetric key to authenticate message with, it is
used to do MAC of the message, so when the want to communicate the use
this key, and to get freshness of the message the use a counter, so the
packet will look as: [counter, Mac(data||counter), data].
what do need to think about to get it secure?
is it ok to use counter as a freshness value, and send it unprotected

.

Relevant Pages

  • Re: Seeking advice on Aironet 1232 config for visitor and staff access
    ... I worked on this yesterday and used IAS to ... authenticate visitors based on their MAC address. ... We only have a couple of Dell switches ...
    (comp.dcom.sys.cisco)
  • Re: Please dont shoot me but......
    ... Wouldn't a Mac firewall client acheive this? ... "Jim Harrison (ISA SE)" wrote: ... Client for Apple Mac's that already authenticate to AD ...
    (microsoft.public.isa.clients)
  • Re: AD will authenticate any machine?
    ... > Getting an ip address is not a function of either NT4 or Active Directory. ... > If machines were limited on your network, it wasn't because of the nt4 ... >> authenticate to get into the resource they want to get into. ... authenticate by approved MAC address only? ...
    (comp.os.ms-windows.nt.admin.security)
  • Re: WPA and authenticating to MS AD
    ... > Deano, we need a bit more information in order to help. ... We have WPA Enterprise with name and PW authentication to a Radius ... WPA is done after you log into the Mac. ... MS AD requires you to authenticate at the login screen (before you have ...
    (comp.sys.mac.system)
  • Re: Authentication of a messages using a counter and a MAC
    ... We have a messages, 128 bit key, counter, AES, and OMAC and want to ... authenticate a stream of messages using ... Include the MAC in the transmitted message, ...
    (sci.crypt)