Minimal block count number(upcomingRevealBlockNo): Even if the Entropy Register Tx is created immediately after the length of the entropy chain is filled, secure entropy generation does not happen. If the block number of the last element of the entropy chain is '11' and the 'minimal block count number' is 1, for secure entropy to be generated, TX must occur in 11+1 blocks or more. The 'minimum number of blocks' is a variable. The higher this value, the higher the contract can obtain entropy reliability, but the user has to wait that much longer. The initial setting is 1, even if the value increases in the future, it should be maintained at an appropriate level considering the user wait time. However, sometimes or always, in the case where more TXs than the length of the entropy chain occurs within blocks less than the 'minimal block count number', the entropy chain accepts all TXs without reverting them. And when the contract draws lots in the entropy chain, it calculates all the elements entered in the entropy chain. It exceeds the set length of the entropy chain, but the longer the chain, the higher the reliability of the entropy, so there is no reason for the contract to reject TXs. Although the length of entropy increases, the order in which users receive secure entropy does not change, and the process proceed sequentially. As a result, the length of the entropy chain is constant and, at the same time, has the feature of a variable.