International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 17 August 2015

Ritam Bhaumik, Mridul Nandi
ePrint Report ePrint Report
In \'Turning Online Ciphers Off\', a class of constructions was defined based on layers of secure online ciphers interleaved with simple mixing layers (like reversing and block-shifting). Here we show that an SPRP construction proposed in the work cited is insecure. Howevewr, the same construction is secure under the assumption that the underlying construction is online-but-last ciphers. We include a simpler proof for beyond-birthday security of other constructions proposed in the same work.

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