With the continuous development of blockchain technology， the block transmission delay has become a performance bottleneck of the scalability of the blockchain system. Remote Direct Memory Access （RDMA） technology， which supports high-bandwidth and low-delay data transmission， provides a new idea for block transmission with low latency. Therefore， a block catalogue structure for block information sharing was designed based on the characteristics of RDMA primitives， and the basic working process of block transmission was proposed and implemented on this basis. Experimental results show that compared with TCP（Transmission Control Protocol） transmission mechanism， the RDMA-based block transmission mechanism reduces the transmission delay between nodes by 44%， the transmission delay among the whole network by 24.4% on a block of 1 MB size， and the number of temporary forks appeared in blockchain by 22.6% on a blockchain of 10 000 nodes. It can be seen that the RDMA-based block transmission mechanism takes advantage of the performance of high speed networks， reduces block transmission latency and the number of temporary forks， thereby improving the scalability of the existing blockchain systems.

A group signature scheme was designed on conic curve Cn(a,b) over Zn. It can be applied in system of E-cash issuance. The scheme security is based on difficulties in factorizing large integer and computing discrete logarithm on Abel group (Cn(a,b),). By fetching NAF in calculating the multiples of an element in a group, 1/4 amount of computation was reduced. Compared with classical group signature, the conic analog over Zn has strongly improved the security of computing discrete logarithm. Compared with its counterparts based on elliptic curves over Zn, the conic analog is easier to accomplish, for they not only maintain the existing advantages but also advance with more advantages such as convenient plaintext embedding and speedy operation.