A Theoretical DPA-Based Cryptanalysis of the NESSIE Candidates FLASH and SFLASH

Within the NESSIE (New European Schemes for Signatures, Integrity, and Encryption) project, the signature schemes FLASH and SFLASH have been proposed for the use on low-cost smartcards.We show theoretically how differential power analysis (DPA) can be used to reveal the complete secret key in possible smartcard implementations of FLASH and SFLASH. To our knowledge no smartcard implementations of these schemes are available at the moment, so an experimental verification of this attack has not been done so far.