One-Time Programs from Commodity Hardware.

One-time programs, originally formulated by Goldwasser et al. [26], are a powerful cryptographic primitive with compelling applications. Known solutions for one-time programs, however, require specialized secure hardware that is not widely available (or, alternatively, access to blockchains and very strong cryptographic tools). In this work we investigate the possibility of realizing one-time programs from a recent and now more commonly available hardware functionality: the counter lockbox. A counter lockbox is a stateful functionality that protects an encryption key under a user-specified password, and enforces a limited number of incorrect guesses. Counter lockboxes have become widely available in consumer devices and cloud platforms. We show that counter lockboxes can be used to realize one-time programs for general functionalities. We develop a number of techniques to reduce the number of counter lockboxes required for our constructions, that may be of independent interest.