Cryptology ePrint Archive: Report 2019/624

Nonces are Noticed: AEAD Revisited

Mihir Bellare and Ruth Ng and Björn Tackmann

Abstract: We draw attention to a gap between theory and usage of nonce-based symmetric encryption, under which the way the former treats nonces can result in violation of privacy in the latter. We bridge the gap with a new treatment of nonce-based symmetric encryption that modifies the syntax (decryption no longer takes a nonce), upgrades the security goal (asking that not just messages, but also nonces, be hidden) and gives simple, efficient schemes conforming to the new definitions. We investigate both basic security (holding when nonces are not reused) and advanced security (misuse resistance, providing best-possible guarantees when nonces are reused).

Category / Keywords: secret-key cryptography / Nonce, Authenticated Encryption, Symmetric Encryption, GCM

Original Publication (with major differences): IACR-CRYPTO-2019

Date: received 1 Jun 2019

Contact author: mihir at eng ucsd edu,ring@eng ucsd edu,bta@zurich ibm com

Available format(s): PDF | BibTeX Citation

Version: 20190603:071253 (All versions of this report)

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