Bitcoin clients are grouped into types and analysed from a usability and security perspective. Security is very important for Bitcoin clients as they are used to manipulate money, and poor security leads to direct loss of money. Various threats are evaluated, including malware infestations, theft of files, hostile takeover of servers and hardware failures.

Security implications of additional features and future enhancements are also assessed. Various client types rely on significantly different security assumptions. While some clients are immune to hostile takeover of servers, for other clients this results in theft of money. None of the current clients are able to resist malware effectively. Additional features usually increase either security or usability, though some features improve both.

The current choice of Bitcoin clients and their feature set is much richer than  one year ago. New versions with more features are released very often. One of the future enhancements, multi-signature transactions, significantly increases security as it protects the money even if a client is totally compromised.

The author of this papers looks at some of the remedies that can improve overall security. They argue that the ussability and user-friendliness of Bitcoin is improved with deterministic wallets, QR
codes and Bitcoin URIs. Wallet encryption, watch-only wallets and paper backups enhance security of Bitcoin clients. These features together brought Bitcoin user experience much closer to that of existing payment systems.

To find out more, read this research report!