A COMPUTER-IMPLEMENTED METHOD OF APPLYING A FIRST FUNCTION TO EACH DATA ELEMENT IN A DATA SET, AND A WORKER NODE FOR IMPLEMENTING THE SAME

There is provided a computer-implemented method of applying a first function to each data element in a first data set, the method comprising (i) determining whether each data element in the first data set satisfies a criterion, wherein the criterion is satisfied only if the result of applying the first function to the data element is equal to the result of applying a second first data set satisfies a criterion function to the data element; (ii) forming a compressed data set comprising the data elements in the first data set that do not satisfy the criterion; (iii) applying the first function to 10 each data element in the compressed data set; and (iv) forming an output based on the results of step (iii); wherein steps (i)-(iv) are performed using multiparty computation, MPC, techniques. A corresponding system and worker node are also provided.