## Cryptology ePrint Archive: Report 2013/595

Enhanced certificate transparency (how Johnny could encrypt)

Mark D. Ryan

Abstract: The certificate authority'' model for authenticating public keys of websites has been attacked in recent years, and several proposals have been made to reinforce it. We develop and extend certificate transparency'', a proposal in this direction, so that it efficiently handles certificate revocation. We show how this extension can be used to build a secure end-to-end email or messaging system using PKI with no requirement to trust certificate authorities, or to rely on complex peer-to-peer key-signing arrangements such as PGP. We believe this finally makes end-to-end encrypted email as usable as encrypted web browsing is today, addressing the concerns of a classic paper explaining the difficulties users face in encrypting emails (Why Johnny can't encrypt'', 1999). Underlying these ideas is a new attacker model appropriate for cloud computing, which we call malicious-but-cautious''.

Category / Keywords: applications / public key certificates

Date: received 13 Sep 2013, last revised 13 Sep 2013

Contact author: m d ryan at cs bham ac uk

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2013/595

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