Andrew Betty KCA=Initial key K0 in s/w KCB=Initial key K0 in s/w KCB=Initial key K0 in s/w KCA=Initial key K0 in s/w KCi= KCA + KCB KCi= KCA + KCB KCo= KCA + KCB KCo= KCA + KCB Use KCi for reading, and Use KCi for reading, and KCo for writeing to the KCo for writeing to the chanell for a while chanell for a while Requset a new sesion key Requset a new sesion key DES(KCo,RSA(BP,K1A)) KRB=DES(KCo,RSA(AP,K1B)) \_____________ ______________/ KCi=KCA+KCB \ / KCi=KCB+KCA KCo=K1A+KCB X KCo=K1B+KCA _____________/ \______________ / \ Sevice new key request TA=DES(KCi,KRB) K1B=RSA(AS,TA) KCi=K1A+K1B