2019/01/28 by Mauro Conti, Conti, Mauro, Ankit Gangwal +3 · 1 citation
Computer Science · #Blockchain Technology Applications and Security #Cryptography and Data Security #Cryptography and Security (cs.CR) #Distributed systems and fault tolerance #FOS: Computer and information sciences
paper · pdf · doi:10.48550/arxiv.1901.10019
openalex publication_date 2019/01/28 · openalex created_date 2022/07/30 · openalex updated_date 2026/07/28
Recently, an ingenious protocol called Algorand has been proposed to overcome\nthese limitations. Algorand uses an innovative process - called cryptographic\nsortition - to securely and unpredictably elect a set of voters from the\nnetwork periodically. These voters are responsible for reaching consensus\nthrough a Byzantine Agreement (BA) protocol on one block per time, guaranteeing\nan overwhelming probability of linearity of the blockchain.\n In this paper, we present a security analysis of Algorand. To the best of our\nknowledge, it is the first security analysis as well as the first formal study\non Algorand. We designed an attack scenario in which a group of malicious users\ntries to break the protocol, or at least limiting it to a reduced partition of\nnetwork users, by exploiting a possible security flaw in the messages\nvalidation process of the BA. Since the source code or an official simulator\nfor Algorand was not available at the time of our study, we created a simulator\n(which is available on request) to implement the protocol and assess the\nfeasibility of our attack scenario. Our attack requires the attacker to have a\ntrivial capability of establishing multiple connections with targeted nodes and\ncosts practically nothing to the attacker. Our results show that it is possible\nto slow down the message validation process on honest nodes, which eventually\nforces them to choose default values on the consensus; leaving the targeted\nnodes behind in the chain as compared to the non-attacked nodes. Even though\nour results are subject to the real implementation assumption, the core concept\nof our attack remains valid.\n