Two most important goals of server assisted signature schemes are to aid small and mobile devices in computing digital signatures and to provide immediate revocation of signing capabilities. In this paper, we introduce an efficient scheme named server assisted one-time signature (SAOTS) alternative to server assisted signature scheme introduced by Asokan et al. Extended the Lamport's one-time signatures by utilizing hash chains, this new scheme's advantages are two-folds; first of all, it is communication-efficient running in fewer rounds, two instead of three, secondly, verification of server's signature can also be performed off-line resulting in real-time efficiency in computation as well as flexibility in the public-key signature scheme to be used. The experiments we have conducted showed that at least 40% gain in performance is obtained if SAOTS is preferred. © Springer-Verlag 2004.