Tight Security of TNT: Reinforcing Khairallah's Birthday-bound Attack

ePrint Report: Tight Security of TNT: Reinforcing Khairallah's Birthday-bound Attack

Ashwin Jha, Mridul Nandi, Abishanka Saha

In a recent paper, Khairallah demonstrated a birthday-bound attack on TNT, thereby invalidating its (beyond-the-birthday-bound) CCA security claims. In this short note, we reestablish a birthday-bound CCA security bound for TNT. Furthermore, using a minor variant of Khairallah's attack, we show that our security bound is tight. We provide a rigorous and complete attack advantage calculations to further enhance the confidence in Khairallah's proposed …

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