This paper analyses the main mode exchange of IKE with digital signature,pointing out the existing security problem about identity protection of the initiator,which also can be found in IKEv2 with digital signature.

New modifications ar e proposed to alleviate the identity protection defects in Internet Key Exchange( IKE)protocol with digital signature authentication method and pre-shared key a uthentication method in main mode,compared with previous works which protect on ly one party,new modifications protect both identities of the two parties,rem aining the framework of ISAKMP and the symmetry of IKE.

Then it discusses the function of identity protection, and how to implement the identity protection in key exchange protocol, which protects the participants identity.

Lack of the Right to judicial remedy of Suspects physical protection is not suitable for China which makes great efforts to construct monocracy country.

In order to perfect mechanism of witness testifying before the court, firstly, we should establish the personal protection system for witness;secondly, we should also stipulate the legal sanction clause to witness who refuses to testify before the court.