Since key pre-distribution schemes based on symmetric key can not completely solve security problems of keys distribution in WSN

a new public key based key distribution scheme was proposed.In the scheme

public key set was generated by an initial public key set and a hash function in base station.Each sensor device was pre-distributed one public/private pair-wise key from public key set and a public key subset from the initial public keys set.Owing to uniqueness of private key

not only the communication security problems could be improved for WSN.but also the sensor-memory cost could be decreased.With the theorem of random-graph theory

the connectivity and scalability were illustrated.The results showed that the scheme was superior to the traditional key pre-distribution schemes.