Abstract: Real networks especially heterogeneous networks consist of several cooperating sub-networks which belong to different trust domains which are independent and autonomous.The trust domains are maintained by different PKGs.A novel ID-based cross-domain signcryption scheme was proposed which is no restriction on PKG system parameters so that public system parameters,system master keys and system public keys can be totally different.Based upon this signcryption scheme,a cross-domain session key generation scheme was presented.Our cross-doamin signcryption protocol was proved to be secure in the random oracle model assuming the bilinear Diffle-Hellman problem is hard.It satisfies the basic security requirements confidentiality,unforgeability,non-repudiation and public verifiability.The scheme not only achieves cross-domain signcryption,but also makes no restriction on PKG system parameters on condition that computation overheads are little increased.

Key words: Identity-based,Signcryption,Cross-domain,Key agreement