Cryptology ePrint Archive: Report 2012/331

Homomorphic Authentication Codes for Network Coding

Zhaohui Tang

Abstract: Authentication codes (A-codes) are a well studied technique to provide unconditionally secure authentication. An A-code is defined by a map that associates a pair formed by a message and a key to a tag. A-codes linear in the keys have been studied for application to distributed authentication schemes. In this paper, we address the dual question, namely the study of A-codes that are linear in the messages. This is usually an undesired property, except in the context of network coding. Regarding these A-codes, we derive some lower bounds on security parameters when key space is known. We also show a lower bound on key size when security parameter values are given (with some special properties) and construct some codes meeting the bound. We finally present a variant of these codes that authenticate multiple messages with a same key while preserving unconditional security.

Category / Keywords: Authentication codes; unconditional security; network coding; pollution attacks

Date: received 10 Jun 2012, last revised 2 Nov 2012

Contact author: TANG0209 at e ntu edu sg

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Version: 20121103:035426 (All versions of this report)

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