RLWE/PLWE equivalence for the maximal totally real subextension of the 2rpq-th cyclotomic field

We generalise our previous work by giving a polynomial upper bound on the condition number of certain quasi-Vandermonde matrices to es tablish the equivalence between the RLWE and PLWE problems for the totally real subfield of the cyclotomic fields of conductor 2r , 2rp and 2rpq with r ≥ 1 and p, q arbitrary primes. Moreover, we give some cryptographic motivations for the study of these subfields.Agencia Estatal de Investigació