International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 03 September 2012

Sebastian Kutzner, Phuong Ha Nguyen, Axel Poschmann
ePrint Report ePrint Report
Threshold Implementation (TI) is an elegant and widely accepted countermeasure against

1-st order Differential Power Analysis (DPA) in Side Channel

Attacks. The 3-share TI is the most efficient version of TI,

but so far, it can only be applied to 50\\% of all 4-bit S-boxes.

In this paper, we study the limitations of decomposition and introduce factorization

to enable the 3-share TI for any optimal 4-bit

S-box. We propose an algorithm which can decompose any optimal 4-bit

S-box to quadratic vectorial boolean functions with a time complexity of $2^{19}$.

Furthermore, we use our new methodology in combination with decomposition to optimize ciphers utilizing many different

S-boxes, and,

to highlight the strength of our new methodology, we construct a 3-share Threshold Implementation of SERPENT which was believed to be not possible until now. Last, we show how to implemented all SERPENT S-boxes with only one mutual core.

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