On the importance of protecting Δ in SFLASH against side channel attacks

Katsuyuki Okeya, Tsuyoshi Takagi, Camille Vuillaume

研究成果: ジャーナルへの寄稿学術誌査読

11 被引用数 (Scopus)


SFLASH was chosen as one of the final selection of the NESSIE project in 2003. It is one of the most efficient digital signature scheme and is suitable for implementation on memory-constrained devices such as smartcards. Side channel attacks (SCA) are a serious threat to memory-constrained devices. If the implementation on them is careless, the secret key may be revealed. In this paper, we experimentally analyze the effectiveness of a side channel attack on SFLASH. There are two different secret keys for SFLASH, namely the proper secret key (s, t) and the random seed Δ used for the hash function SHA-1. Whereas many papers discussed the security of (s, t), little is known about that of Δ. Steinwandt et al. proposed a theoretical DPA for finding Δ by observing the XOR operations. We propose another DPA on Δ using the addition operation modulo 232, and present an experimental result of the DPA. After obtaining the secret key Δ, the underlying problem of SFLASH can be reduced to the C* problem broken by Patarin. From our simulation, about 1408 pairs of messages and signatures are needed to break SFLASH. Consequently, SHA-1 must be carefully implemented in order to resist SCA on SFLASH*.

ジャーナルIEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
出版ステータス出版済み - 1月 2005

!!!All Science Journal Classification (ASJC) codes

  • 信号処理
  • コンピュータ グラフィックスおよびコンピュータ支援設計
  • 電子工学および電気工学
  • 応用数学


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