  The blockchain technology enables mutually untrusting participants to reach
consensus on the state of a distributed and decentralized ledger (called a
blockchain) in a permissionless setting. The consensus protocol of the
blockchain imposes a unified view of the system state over the global network,
and once a block is stable in the blockchain, its data is visible to all users
and cannot be retrospectively modified or removed. Due to these properties, the
blockchain technology is regarded as a general consensus infrastructure and
based on which a variety of systems have been built. This article presents a
study and survey of permissionless blockchain systems in the context of secure
logging. We postulate the most essential properties required by a secure
logging system and by considering a wide range of applications, we give
insights into how the blockchain technology matches these requirements. Based
on the survey, we motivate related research perspectives and challenges for
blockchain-based secure logging systems, and we highlight potential solutions
to some specific problems.
