Weaknesses in some recent key agreement protocols

B. Arazi ( see ibid., vol. 29, no. 11, p. 966-7, 1993 ) recently proposed a way to integrate the DSS (digital signature standard) to the Diffie-Hellman key exchange system to obtain an authenticated key establishment mechanism for secret session keys. The authors point out the following weakness in the Arazi system: if one key is compromised then the others will be disclosed as well. A similar weakness appears also in another recently presented key distribution system