Paper 2017/243

Key Recovery: Inert and Public

Colin Boyd and Xavier Boyen and Christopher Carr and Thomas Haines

Abstract

We propose a public key infrastructure framework, inspired by modern distributed cryptocurrencies, that allows for tunable key escrow, where the availability of key escrow is only provided under strict conditions and enforced through cryptographic measures. We argue that any key escrow scheme designed for the global scale must be both inert --- requiring considerable effort to recover a key --- and public --- everybody should be aware of all key recovery attempts. To this end, one of the contributions of this work is an abstract design of a proofof-work scheme that demonstrates the ability to recover a private key for some generic public key scheme. Our framework represents a new direction for key escrow, seeking an acceptable compromise between the demands for control of cryptography on the Internet and the fundamental rights of privacy, which we seek to align by drawing parallels to the physical world.