Blockchain privacy‐preserving smart contract centric multiple multiparty key agreement over large WANETs

Abstract

Abstract With the rapid increase in the popularity of groupware applications whose security mainly relied on the key being used, which made multi‐party/group secret key agreements significant. However, the brute‐force attacks to interpret the group key made group communication vulnerable. The logical solution to overcome this is changing the group key frequently. In this direction, we propose blockchain‐based multiple shared keys agreement among a group of participants. As with conventional methods, the proposed protocol does not rely on strong random number generation and/or master key. In this technique, the privacy‐preserving smart contract acts as group controller (GC) and forms two parties with each of the other nodes. The GC, while generating these two‐party keys in the first round instead of exchanging one public key, it exchanges “ m ” public keys with each of the other nodes and generates m 2 shared two‐party keys with each of the respective nodes. Now in the second round, GC generates m 2 sequential products of two‐party shared keys and stores them securely as private data objects in the privacy‐preserving smart contract. Next GC computes m 2 sequential public keys to each of the respective nodes by multiplying these products with the inverse of individual members shared keys sequentially of the group nodes in trusted execution environment and shares them with respective group nodes. On receiving respective public keys, each group node computes the multiple multiparty shared keys by multiplying it with their individual shared keys. Furthermore, an upper limit for the number of shared keys obtained in terms of the number of keys exchanged.