Details

Autor(en) / Beteiligte

• Chen, Yu Long
• Luykx, Atul
• Mennink, Bart
• Preneel, Bart

Titel

Systematic Security Analysis of Stream Encryption With Key Erasure

Ist Teil von

• IEEE transactions on information theory, 2021-11, Vol.67 (11), p.7518-7534

Ort / Verlag

IEEE

Erscheinungsjahr

2021

Quelle

IEEE Xplore

Beschreibungen/Notizen

• We consider a generalized construction of stream ciphers with forward security. The design framework is modular: it is built from a so-called layer function that updates the key and (optionally) the nonce and generates a new pseudorandom output stream. We analyze the generalized construction for four different instantiations: two possible layer functions that are in turn instantiated with either a block cipher or a pseudorandom function. We prove that each of these instantiations gives a stream cipher that is pseudorandom and forward secure in the multi-user setting with a very tight bound. A comprehensive analysis shows that the two block cipher based instantiations achieve very similar bounds. For the pseudorandom function based instantiations there is no clear winner: either layer can be beneficial over the other one, depending on the choice of parameters. By instantiating the pseudorandom function with a generic construction such as the sum of permutations, we obtain a highly efficient and competitive stream cipher based on an n-bit block cipher that is secure beyond the <inline-formula> <tex-math notation="LaTeX">2^{\text {n}/2} </tex-math></inline-formula> birthday bound.