Secure rewarding schemes

Proposes a secure rewarding scheme in which a reward provider publishes a problem and provides a reward for a person who can supply him a satisfactory solution to the problem. The first qualified claimant with a satisfactory solution to the problem is selected to obtain the reward. The selected claimant can obtain the reward from the reward provider without revealing his identity. Nobody except the selected claimant can get the reward, and the provider cannot decline the selected claimant his entitled reward. In addition, we also propose another secure rewarding scheme with two-way untraceability to protect the privacy of the reward provider as well.