Cryptology ePrint Archive: Report 2003/001

A Mode of Operation with Partial Encryption and Message Integrity

Philip Hawkes and Gregory G. Rose

Abstract: At the recent AES Modes of Operation Conference, several modes of operation were proposed for using a block cipher to provide both confidentiality and authentication. These modes require only a little more work than the cost of encryption alone, and come with proofs of security. However, these modes require the entire message to be sent in encrypted form. This can cause problems in situations where some of the message neeeds to be sent in plaintext while still being authenticated. This paper describes a simple variation that allows any choice of message blocks to be sent in plaintext form rather than in encrypted form. This mode, Partial Encryption with Message Integrity (PEMI), is shown to be secure for message integrity and message secrecy.

Category / Keywords: secret-key cryptography / Partial encryption, message integrity, modes of operation

Date: received 3 Jan 2003

Contact author: ggr at qualcomm com

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Version: 20030107:075746 (All versions of this report)

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