Templates as Master Keys

We introduce two new attacks: the single-bit template attack and the template-enhanced DPA attack. The single-bit template attack can be used very effectively to classify even single bits in a single side channel sample with a high probability of correctness. The templateenhanced DPA attack, combines traditional DPA with single-bit template attacks to show that if an adversary has access to a test card with even a slightly biased RNG, then he/she can break protected cryptographic implementations on a target card even if they have perfect RNGs. In support of our claim, we report results from experiments on breaking two implementations of DES and AES protected by the masking countermeasure running on smartcards of different manufacturers. In light of these results, the threat of template attacks, generally viewed as intrinsically difficult to mount, needs to be reconsidered.

• Type: Conference
• Year: 2005
• Where: CHES
• Authors: Dakshi Agrawal, Josyula R. Rao, Pankaj Rohatgi, Kai Schramm
• Keywords: CHES 2005, Cryptography, DPA Attack, Single-bit Template Attacks, Template-enhanced Dpa Attack