  Current blockchains are restricted by the low throughput. Aimed at this
problem, we propose Txilm, a protocol that compresses the size of transaction
presentation in each block to save the bandwidth of the network. In this
protocol, a block carries short hashes of TXIDs instead of complete
transactions. Combined with the sorted transactions based on TXIDs, Txilm
realizes 80 times of data size reduction compared with the original
blockchains. We also evaluate the probability of hash collisions, and provide
methods of resolving such collisions. Finally, we design strategies to protect
against potential attacks on Txilm.
