Large-scale sensor nodes were usually deployed in potentially adverse or even hostile environment

so the security in these networks was very important.Due to its constraints on node cost

size and power dissipation

sensor’s energy and capabilities on computation

storage and communication were considerably weak compared with general computers.It leaded to many new challenges for designing of key management protocols in WSN.Therefore

a lite-CA based key pre-distribution scheme was suggested.The traits of CA-based authentication framework and identity-based authentication framework were combined by this scheme.Further

the scheme was efficiently implemented based on quadratic residue theory.