An efficient delegation-based roaming payment protocol against denial of service attacks

The payment system for many kinds of mobile devices, such as smart phones, PDAs and mobile tablets, will be increasingly developed in the near future. Youn and Lim in 2010 proposed an improved delegation-based authentication protocol add the unlinkability property for protecting user´s privacy. Furthermore, this paper designs a new roaming payment system mobile environment combining the concepts of PayWord and the delegation-based authentication. The denial of service (DoS) threats on Youn and Lim, and multiple VLRs have also been considered. The proposed protocol is specially suitable off-line fast payments and provides buyer´s privacy by applying anonymity and unlinkability techniques. Further, the computational costs are effectively reduced by using hash chains payments of small denomination.