Abstract: It has been proven that security risks exist in most of the password-based cross-domain authentication and key agreement protocols or Kerberos protocol.It is necessary to propose a more effective protocol to ensure the communi-cating security in the area of finance and aerospace,which require high level communicating security.This paper proposed a cross-domain PKI-based key agreement protocol.This protocol can efficiently solve the key exposure problem in which the password guessing and man-in-the-middle attack is enabled.This problem is resulted from using share-key encryption and decryption to assure the security of data transmission or Kerberos weak passwords.To solve this pro-blem,this protocol adopts the public key algorithm and uses the Diffie-Hellman protocol to create the session key.Meanwhile,this protocol makes users get rid of repetitive configuration of the cross-domain server public key information,which reduces the complexity of the configuration and the key management between users and servers.Besides,this protocol improves the ability to identify authenticity and the information confidentiality,and is immune to multiple attacking ways.This protocol also has forward security and good expansibility.

Key words: Key agreement,Share key,Diffie-Hellman protocol,Confidentiality