Title: The quest of privacy in public key infrastructure

Authors: Leila Benarous; Benamar Kadri

Addresses: STIC Laboratory, Department of Computer Science, Faculty of Science, University of Abou Bekr Belkaid, Tlemcen, Algeria ' STIC Laboratory, Department of Telecommunications, Faculty of Technology, University of Abou Bekr Belkaid, Tlemcen, Algeria

Abstract: The public key infrastructure (PKI) is the backbone of internet security. It ensures the authenticity, integrity, and non-repudiation. The certified public keys are life-timed. They may be revoked upon personal change, private key exposure or misbehaviour occurrence. Their use is secure and traceable. Yet, this traceability trait and the identity-based certificate usage may violate the user's privacy. Therefore, there needs to be a balance between the accountability and authenticity requirements on the one hand and the privacy demand on the other hand. In this paper, we design a blockchain-based privacy-aware public key infrastructure system, which guarantees the same security properties besides ensuring the privacy. The users have two types of elliptic curve cryptography (ECC) keys, identity-based long-term certified keys and on-the-fly temporal anonymous keys denoted as pseudonyms. These pseudonyms are stored and published on the blockchain. The proposed PKI achieves a similar security level as that of the conventional PKI while ensuring the privacy.

Keywords: public key infrastructure; PKI; blockchain; privacy; elliptic curve cryptography; ECC; pseudonyms; certificates; revocation.

DOI: 10.1504/IJBC.2021.119886

International Journal of Blockchains and Cryptocurrencies, 2021 Vol.2 No.3, pp.244 - 262

Received: 25 Jul 2019
Accepted: 01 Dec 2019

Published online: 22 Dec 2021 *

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