Cryptology ePrint Archive: Report 2004/227

Sign Change Fault Attacks On Elliptic Curve Cryptosystems

Johannes Blömer and Martin Otto and Jean-Pierre Seifert

Abstract: We present a new type of fault attacks on elliptic curve scalar multiplications: Sign Change Attacks. These attacks exploit different number representations as they are often employed in modern cryptographic applications. Previously, fault attacks on elliptic curves aimed to force a device to output points which are on a cryptographically weak curve. Such attacks can easily be defended against. Our attack produces points which do not leave the curve and are not easily detected. The paper also presents a revised scalar multiplication algorithm that provably protects against Sign Change Attacks.

Category / Keywords: public-key cryptography / elliptic curve cryptosystem, fault attacks, smart cards

Date: received 8 Sep 2004, last revised 11 Sep 2004

Contact author: martinmo at upb de

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Version: 20040911:142003 (All versions of this report)

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