Abstract: A method of scalar multiplication for use in elliptic curve-based cryptosystems (ECC) is provided. Scalars are represented using a generic multibase form combined with the non-adjacency property, which greatly reduces the nonzero density in the representation. The method allows for flexibly selecting an unrestricted number of bases and their weight in the representation according to the particular characteristics of a setting, in such a way that computing costs are minimized. A simple, memory-friendly conversion process from binary to multibase representation and an inexpensive methodology to protect the multibase scalar multiplication against simple-side channel attacks are also provided.