A note on an infeasible linearization of some block ciphers. (2nd January 2018)

• Record Type: Journal Article
• Authors: Aragona, Riccardo; Rimoldi, Anna; Sala, Massimiliano
• Is Part Of: Journal of discrete mathematical sciences & cryptography. Volume 21:Number 1(2018)
• Page Start: 209
• Page End: 218
• Publication Date: 2018-01-02
• Subjects: AES -- Block cipher -- Group theory; Computer science -- Mathematics -- Periodicals; Cryptography -- Periodicals; Computer science -- Mathematics; Cryptography; Periodicals; 004.0151
• DOI: 10.1080/09720529.2016.1197598
• Languages: English
• ISSNs: 0972-0529

Abstract

Abstract: A block cipher can be easily broken if its encryption functions can be seen as linear maps on a small vector space. Even more so, if its round functions can be seen as linear maps on a small vector space. We show that this cannot happen for the AES. More precisely, we prove that if the AES round transformations can be embedded into a linear cipher acting on a vector space, then this space is huge-dimensional and so this embedding is infeasible in practice. We present two elementary proofs.