Universal-hash-function-family calculation unit and shared-key generation system

摘要

An input data enlarging unit (100) derives a first enlargement unit output and a second enlargement unit output that are uniquely specified by input data (103) to output the same. The first enlargement unit output and the second enlargement unit output are elements of output data set B which forms a group. An &egr;−&Dgr; hash function calculation unit (101) receives as input the first enlargement unit output to calculate an h&Dgr; function which is specified by hash-function-specifying data (104) and an element of the H&Dgr; function set. The function set H&Dgr; is such that the number of h&egr;H &Dgr; which satisfies h(x)−h(y)=d for an arbitrary element d of the output data set B and two different elements x and y of the output data set B is equal to or smaller than |H&Dgr;|·&egr;. An adding unit (102) adds together the result of calculation of the function H&Dgr; and the second enlargement unit output to output a result of the addition.