New single‐trace side‐channel attacks on a specific class of Elgamal cryptosystem
Parinaz Mahdion, Hadi Soleimany, Pouya Habibi, Farokhlagha Moazami · IET Information Security · 2019
The so‐called attack is one of the most important order‐2 element attacks, as it requires a non‐adaptive chosen ciphertext which is considered as a more realistic attack model compared to adaptive chosen ciphertext scenario. To protect the implementation against attack, several literatures propose the simplest solution, i.e. ‘block the special message ’. In this study, the authors conduct an in‐depth research on the attack based on the SMA and Montgomery ladder (ML) algorithms. They show that despite the unaccepted ciphertext countermeasure, other types of attacks are applicable to specific classes of Elgamal cryptosystems. They propose new chosen‐message power‐analysis attacks with order‐4 elements which utilise a chosen ciphertext c such that where p is the prime number used as a modulus in Elgamal. Such a ciphertext can be found simply when . They demonstrate that ML and SMA algorithms are subjected to the new ‐type attack by utilising a different ciphertext. They implement the proposed attacks on the TARGET Board of the ChipWhisperer CW1173 and the proposed experiments validate the feasibility and effectiveness of the attacks by using only a single power trace.