Wireless networks play a key role in national critical information infrastructure. Mainly due to lack of a protected physical boundary, wireless communications are inherently less secure than its wired counterpart. Privacy has been ranked as the top security concern of wireless users. Inadequate privacy protection can result in significant network information retrieval that enables the adversaries to perform destructive denial-of-service (DoS) attacks, or even paralyze the entire wireless networks. While confidentiality of the message can be ensured through content encryption, it is much more challenging to provide privacy service for wireless networks. In fact, privacy is one of the most notable challenges looming on the horizon that threatens successful deployment of WSN. In this research, we propose to design efficient cryptographic algorithms and network security protocols that can achieve privacy-preserving communications for both MANET and WSN. More specifically, we plan to: (i) Develop efficient cryptographic algorithms that can achieve unconditional privacy-preserving communications even in the presence of local eavesdropper while reconciling communication accountability; (ii) Develop efficient anonymous authentication schemes and protocols for secure user access control and anonymous routing in MANET and WSN. That is, while each user is being authenticated, the user's real identity and location will remain secret for adversaries. (iii) Establish a scientific foundation for theoretical characterization and quantitative measurement of privacy in secure network communications. Our research is expected to have a significant impact on personal privacy, national critical information security as well as homeland security.