So does this mean the GnuTLS client generates the "shared key" on its own ?
When I read that the DH parameters are useful only to the server, perhaps I got confused that the server generates P, G and the "Shared Key" and sends the "Shared Key" to the client. So this is the correct logic: 1) GnuTLS server generates P & G and sends it to the client 2) GnuTLS client selects a random number X and sends G(power of X) mod P to server 3) GnuTLS server selects a random number Y and sends G(power of Y) mod P to client 4) Both client and server independently calculates the "shared key" Thanks for clearing my confusion Ramg On Thu, Aug 27, 2009 at 11:32 AM, Nikos Mavrogiannopoulos <[email protected]>wrote: > Ram G wrote: > > Hi, > > "....Also note that the DH parameters are only useful to servers. Since > > clients use the parameters sent by the server, it's of no use to call > this > > in client side....." > [...] > > 1) Alice and Bob decides on the prime P and generator G > > 2) Alice decides on a random number X and sends G(power of X) mod P to > Bob > > 3) Bob decides on a random number Y and sends G(power of Y) mod P to > Alice > > 4) Both Bob and Alice can calculate the shared secret on their own from > > steps 2 and 3. > > > > So my question is - why are the DH params not generated in the client > side > > too ? What is the point in generating the DH params and the shared key in > > the server (Bob) and sending it to the client (Alice) - won't it be > > accessible to an attacker when it is sent in the clear ? > > Hello, > They will be available to attackers but the security of the DH > cryptosystem doesn't depend on the secrecy of the group and generator. > The security depends on the random numbers X and Y. > > regards, > Nikos > >
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