  This study proposes a novel solution that provides secure interoperability
for blockchains, which improves the overall scalability of the whole blockchain
network. In our solution, a cross-chain task will build a one-time
cross-blockchain contract. Each blockchain system can follow the contract to
complete or this task. The result of tasks is bound with the system, hence can
be anchored to all other blockchain systems through the gossip network. This
work shows our result can provide linear scalability for the whole system and
achieve consistency among honest systems.
