Computation device using shared shares

Some embodiments are directed to a computation device for performing a computation on at least a set of values. The values are stored in memory as a plurality of shares that define the value. An operation of the computation may be performed on a set of input values to obtain an output value. The output value may be defined by at least one shared share and at least one computed share. The at least one shared share may also define a further value, e.g., an output of a previously performed computation or an output of a further operation performed in parallel with the operation. The at least one computed share is computed from the at least one shared share and shares of the set of input values. A fault in the shared share affects the further value but a fault in the computed share, complicating share reduction attacks.