Abstract: Authentication is one of the basic service for information security,and password authentication is the most common authentication method,but currently there is much risk in setting user password.On the basis of analyzing the current setting user password problem,we presented user password protection’s offensive-defensive game model in big data environment,and pointed attacker could improve ability for deciphering user password with big data analysis technology.However,for user to ensure security or reduce risk,more effective password,identity cross-certification techno-logy or dynamic track user access information system behavior technology,as well as lower big data analysis cost are needed.Countermeasure was presented and user data portrait thinking was used to establish information system user identity cross-certification model in big data environment.Validity of model was verified through simulation experiment.

Key words: Big data,Password authentication,Risk analysis,Data portrait,Identity cross-certification model