Cryptanalysis of Gu's ideal multilinear map
Résumé
In March, 2015 Gu Chunsheng proposed a candidate ideal multilinear map [9]. An ideal
multilinear map allows to perform as many multiplications as desired, while in k-multilinear maps
like GGH [5] or CLT [3,4] one we can perform at most a predetermined number k of multiplications.
In this note, we show that the extraction Multilinear Computational Diffie-Hellman problem (ext-
MCDH) associated to Gu’s map can be solved in polynomial-time: this candidate ideal multilinear
map is insecure. We also give intuition on why we think that the two other ideal multilinear maps
proposed by Gu in [9] are not secure either.