SSH Protocol v.2 protocol start - continued


Upon receipt of KEXINIT packet, both client and server
Calculate intersection of supported/allowed ciphers, etc
Run selected key exchange algorithm
Usually Diffie Hellman

D-H key exchange
Secure way for two parties to derive a shared key
Safe against eavesdroppers
Perfect Forward Secrecy
Exchange is authenticated with hash of
Client & server version strings
Payloads of client & server KEXINIT packets
Server host key
Intermediate D-H exchange values
Derived shared secret