>why can't the client calculate the shared secret on its own ? Client calculates the Shared secret on its own when it receives the server's public key. >What is the point of generating the DH params and the shared key in the server (Bob) and sending it to the client (Alice)
Server only sends the DH Parameters (P and G) and its Public Key to the client. It doesn't send the its Shared Key anywhere. -Sandeep On Wed, Aug 26, 2009 at 6:37 AM, Ram G <mydevfor...@gmail.com> wrote: > Thank you for your response. I hope you can help me get answers to the > following questions - > > 1) Why do we need to deviate from the Diffie-Hellman Key exchange theory > - why can't the client calculate the shared secret on its own ? > > 2) What is the point of 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 ? > > Thanks > > Ramg > > On Tue, Aug 25, 2009 at 4:56 PM, Dr. Stephen Henson <st...@openssl.org>wrote: > >> On Tue, Aug 25, 2009, Ram G wrote: >> >> > Hi, >> > >> > I'm trying to use openSSL without certificates and authentication >> through >> > Anonymous Diffie-Hellman key exchange. I have managed to successfully >> > exchange messages between server and client by modifying some of the >> sample >> > programs available with the source code. >> > >> > The salient features of the modified client and server test programs >> are: >> > 1) Not loading certificates >> > 2) Loading the DH params in the server by reading dhparams.pem >> > 3) Setting the cipher to ADH-AES128-SHA on both client and server >> > >> > I have a question regarding the DH key exchange - don't we have to load >> DH >> > params on the client side as well ? >> > >> > What I have been able to gather from online sources on DH key exchange >> is >> > that >> > >> > 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 >> > >> > In my test program, I did not do anything on the client side to generate >> the >> > shared key. >> > >> > I would really appreciate if someone can shed some light on how >> anonymous DH >> > works in OpenSSL. >> > >> >> The DH parameters are supplied by the server and sent to the client during >> the >> handshake so the client doesn't need any DH parameters. >> >> Steve. >> -- >> Dr Stephen N. Henson. OpenSSL project core developer. >> Commercial tech support now available see: http://www.openssl.org >> ______________________________________________________________________ >> OpenSSL Project http://www.openssl.org >> User Support Mailing List openssl-users@openssl.org >> Automated List Manager majord...@openssl.org >> > >
