  Bitcoin users are directly or indirectly forced to deal with public key
cryptography, which has a number of security and usability challenges that
differ from the password-based authentication underlying most online banking
services. Users must ensure that keys are simultaneously accessible, resistant
to digital theft and resilient to loss. In this paper, we contribute an
evaluation framework for comparing Bitcoin key management approaches, and
conduct a broad usability evaluation of six representative Bitcoin clients. We
find that Bitcoin shares many of the fundamental challenges of key management
known from other domains, but that Bitcoin may present a unique opportunity to
rethink key management for end users.
