Patent ID: 8638944

Claim:
A computing device-implemented method for carrying out a cryptographic process for processing plaintext to generate cipher text using a key, the process including a lookup operation on a table, the method comprising: a processing unit of the computing device executing the steps of: a) masking the key with a random key mask; b) randomly generating n−1 split masks m 1 , . . . , m n-1 ; c) defining a n th split mask m n by masking the random key mask with the plurality of n parts m in 1 , . . . , m in n and the n−1 split masks m 1 , . . . , m n-1 ; d) masking each of the n split masks m 1 , . . . , m n with a random value r 1 ; e) masking the masked key with each of the n masked split masks to generate a split mask masked key; and, e) masking the plaintext with the split mask masked key to produce a table input; and, f) performing the table lookup operation on a masked table using the table input, wherein the masked table comprises the table masked with a mask comprised of a plurality of n parts m in 1 , . . . , m in n.