Cryptography of SSH (2006)

In this example, host .14 (the client) establishes a TCP connection to port 22 of host .11 (the server), the two sides announce SSH versions, and the key exchange initialization takes place. If (otherwise known as DHGEX) is selected, the group to use is negotiated based on the client’s minimum, maximum, and preferred size prime modulus; from which the server chooses an appropriate value (see the SSH2_MSG_KEXDH_GEX_GROUP message in packet 9). Following section 2, the peers will have derived the following information:

As mentioned earlier, if is selected as the key exchange method, the client notifies the server of it’s minimum, preferred, and maximum prime size for the group.

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