Abstract: : In this paper, we study the exhibition of blockchains by investigating the basic prefix profundity, chain qualitycoefficient, and chain development speed coefficient. These three boundaries portray the liveness and consistency of exchangeswhich are significant for the appropriate activity of the blockchain. We analyze how these three boundaries are influenced underan adaptive double-spend attack (ADSA). To keep up the execution of a blockchain against ADSA, the client hubs can utilize abigger number, z, of affirmation blocks for approving a exchange. An examination of the upsides of z expected to accomplish agiven objective likelihood of fruitful attack is accommodated ADSA furthermore, the traditional double-spend attack (TDSA) withvarious framework models. The outcomes show that a bigger worth of z is needed under ADSA. A more reasonable award modelfor attackers is likewise presented. It is tracked down that the normal award of an attacker diminishes quickly to zero as z isexpanded.Keywords: —blockchain, double-spend attack, security, mining, proof-of-work.