CryptoDB
Phil Hebborn
Affiliation: Ruhr University Bochum, Bochum, Germany
Publications
Year
Venue
Title
2020
TOSC
Dasta – Alternative Linear Layer for Rasta
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Abstract
Progress in the areas of multi-party computation (MPC) and fully homomorphic encryption (FHE) caused the demand of new design strategies, that minimize the number of multiplications in symmetric primitives. Rasta is an approach for a family of stream ciphers with an exceptional low AND depth, which equals the number of ANDs per encrypted bit. This is achieved in particular by randomizing parts of the computation with the help of a PRNG, implying that the security arguments rely on the provided randomness and the encryption/ decryption is potentially slowed down by this generation.In this paper we propose a variant of Rasta that achieves the same performance with respect to the AND depth and the number of ANDs per encrypted bit, but does not rely on a PRNG, i.e. is based on fixed linear layers.
2020
ASIACRYPT
Lower Bounds on the Degree of Block Ciphers
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Abstract
Only the method to estimate the upper bound of the algebraic degree on block ciphers is known so far, but it is not useful for the designer to guarantee the security. In this paper we provide meaningful lower bounds on the algebraic degree of modern block ciphers.
Coauthors
- Baptiste Lambin (1)
- Gregor Leander (2)
- Yosuke Todo (1)