Algorithm 2: Reward Spending

[Participant wants to spend the reward] Decrypt $r_{\mathrm{s}}$ using $a_{{\mathrm{K}}_{\mathrm{O}}}^{*}$ [OrderBook operation] //Verify that the associated validation token’s signature is a valid one from the service provider. Verify signature of $T_{\mathrm{V}}$ (identified by $i_{\mathrm{V}}$ entry in $r_s$) if verification passes then     Check that $i_{\mathrm{S}}$ is not already recorded as spent     if $i_{\mathrm{S}}$ is not recorded as spent then         Permit spending         Record $i_{\mathrm{S}}$ as spent     end if end if