Smart card fault attacks on elliptic curve cryptography

Blömmer, Otto, and Seifert presented a fault attack on elliptic curve scalar multiplication called the Sign Change Attack, which causes a fault that changes the sign of the accumulation point. As the use of a sign bit for an extended integer is highly unlikely, this appears to be a highly selective manipulation of the key stream. Here we describe two plausible fault attacks on a smart card implementation of elliptic curve cryptography.