Patent ID: 7933905

Claim:
A universal-hash-function-family calculation device for a communication system that performs calculation using input data and delivers output data, comprising: an input data enlargement unit for receiving the input data and deriving, from the input data through one-to-one mapping, two elements of an output data set which is a set of the output data; a Δ-hash-function calculation unit for receiving hash-function-specifying data that uniquely specifies a hash function from a hash function set, the hash function being an element of the hash function set, to calculate a hash value of the hash function specified by the hash-function-specifying data by using as an input one of the two elements of the output data set derived by the input data enlargement unit; and an adding unit for adding together the hash value calculated by the Δ-hash-function calculation unit and the other of the two elements of the output data set derived by the input data enlargement unit, to output a result of the addition as output data, wherein: the Δ-hash-function calculation unit calculates the hash value of a hash function belonging to a hash function set and specified by the hash-function-specifying data, the hash function set satisfying a condition that a number of elements h of the hash function set satisfying h(x)−h(y)=d is equal to or smaller than a value obtained by multiplying a number of hash functions, which are elements of the hash function set, by a predetermined value, given x and y being two different elements belonging to a codomain set of the hash function set, given d being an arbitrary element belonging to a codomain set of the hash function set.