Cryptology ePrint Archive: Report 2019/034

A Formal Treatment of Hardware Wallets

Myrto Arapinis and Andriana Gkaniatsou and Dimitris Karakostas and Aggelos Kiayias

Abstract: Bitcoin, being the most successful cryptocurrency, has been repeatedly attacked with many users losing their funds. The industry's response to securing the user's assets is to offer tamper-resistant hardware wallets. Although such wallets are considered to be the most secure means for managing an account, no formal attempt has been previously done to identify, model and formally verify their properties. This paper provides the first formal model of the Bitcoin hardware wallet operations. We identify the properties and security parameters of a Bitcoin wallet and formally define them in the Universal Composition (UC) Framework. We present a modular treatment of a hardware wallet ecosystem, by realizing the wallet functionality in a hybrid setting defined by a set of protocols. This approach allows us to capture in detail the wallet's components, their interaction and the potential threats. We deduce the wallet's security by proving that it is secure under common cryptographic assumptions, provided that there is no deviation in the protocol execution. Finally, we define the attacks that are successful under a protocol deviation, and analyze the security of commercially available wallets.

Category / Keywords: cryptographic protocols / digital signatures, blockchains

Original Publication (in the same form): Financial Cryptography 2019

Date: received 14 Jan 2019

Contact author: dimitris karakostas at ed ac uk

Available format(s): PDF | BibTeX Citation

Version: 20190117:231321 (All versions of this report)

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