Cryptology ePrint Archive: Report 2004/344

Modified Parameter Attacks: Practical Attacks against CCA2 Secure Cryptosystems and Countermeasures

Nick Howgrave-Graham and Joseph H. Silverman and Ari Singer and William Whyte

Abstract: We introduce the concept of Modified Parameter Attacks, a natural extension of the idea of Adapative Chosen Ciphertext Attacks (CCA2) under which some CCA2 secure systems can be shown to be insecure. These insecurities can be addressed at the application level, but can also be addressed when cryptographic schemes are being designed. We survey some existing CCA2 secure systems which are vulnerable to this attack and suggest practical countermeasures.

Category / Keywords: public-key cryptography /

Date: received 10 Dec 2004, last revised 11 Dec 2004

Contact author: wwhyte at ntru com

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Version: 20041211:134600 (All versions of this report)

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