A registration apparatus generates shares by secret sharing of a character string with a plurality of modulus and sends the shares to a plurality of server apparatuses to be stored therein. A retrieval apparatus sends shares generated by secret sharing of a retrieval character string with the plurality of modulus to the plurality of server apparatuses. The plurality of server apparatuses execute a subroutine for shares of the each registration character string stored in a storage unit and for each of the plurality of modulus, reconstruct an execution result, and determine whether or not to return the shares of the registration character string stored in the storage unit as a retrieval result. A retrieval apparatus reconstructs shares returned from the plurality of server apparatuses and obtains a retrieval result in which the retrieval character string hits, from the reconstructed result by the Chinese remainder theorem.

Fisher's exact test is efficiently computed through secure computation. It is assumed that a, b, c and d are frequencies of a 22 contingency table, [a], [b], [c] and [d] are secure texts of the respective frequencies a, b, c and d, and N is an upper bound satisfying a+b+c+dN. A reference frequency computation part 12 computes a secure text ([a.sub.0], [b.sub.0], [c.sub.0], [d.sub.0]) of a combination of reference frequencies (a.sub.0, b.sub.0, c.sub.0, d.sub.0) which are integers satisfying a.sub.0+b.sub.0=a+b, c.sub.0+d.sub.0=c+d, a.sub.0+c.sub.0=a+c, and b.sub.0+d.sub.0=b+d. A number-of-patterns determination part 13 determines integers h.sub.0 and h.sub.1 satisfying h.sub.0h.sub.1. A pattern computation part 14 computes [ai]=[a.sub.0]+i, [b.sub.i]=[b.sub.0]i, [c.sub.i]=[c.sub.0]i and [d.sub.i]=[d.sub.0]+i for i=h.sub.0, . . . , h.sub.1, and obtains a set S={([a.sub.i], [b.sub.i], [c.sub.i], [d.sub.i])}.sub.i of secure texts of combinations of frequencies (a.sub.i, b.sub.i, c.sub.i, d.sub.i).

Fisher's exact test is efficiently computed through secure computation. It is assumed that a, b, c and d are frequencies of a 22 contingency table, [a], [b], [c] and [d] are secure texts of the respective frequencies a, b, c and d, and N is an upper bound satisfying a+b+c+dN. A reference frequency computation part 12 computes a secure text ([a.sub.0], [b.sub.0], [c.sub.0], [d.sub.0]) of a combination of reference frequencies (a.sub.0, b.sub.0, c.sub.0, d.sub.0) which are integers satisfying a.sub.0+b.sub.0=a+b, c.sub.0+d.sub.0=c+d, a.sub.0+c.sub.0=a+c, and b.sub.0+d.sub.0=b+d. A number-of-patterns determination part 13 determines integers h.sub.0 and h.sub.1 satisfying h.sub.0h.sub.1. A pattern computation part 14 computes [ai]=[a.sub.0]+i, [b.sub.i]=[b.sub.0]i, [c.sub.i]=[c.sub.0]i and [d.sub.i]=[d.sub.0]+i for i=h.sub.0, . . . , h.sub.1, and obtains a set S={([a.sub.i], [b.sub.i], [c.sub.i], [d.sub.i])}.sub.i of secure texts of combinations of frequencies (a.sub.i, b.sub.i, c.sub.i, d.sub.i).

The invention relates to a device for generating random numbers, comprising a pair of memristors. The pair of memristors comprises a first and a second memristor, each memristor of the pair in turn comprises a top electrode, a bottom electrode and an intermediate layer adapted to switch resistance in response to predetermined voltage values applied between the top electrode and the bottom electrode. Each memristor is operatively connected to an output terminal by means of its bottom electrode. A control logic is connected to the memristors for applying suitable voltages necessary to determine a change of resistance in at least one memristor of the pair.

The invention relates to a device for generating random numbers, comprising a pair of memristors. The pair of memristors comprises a first and a second memristor, each memristor of the pair in turn comprises a top electrode, a bottom electrode and an intermediate layer adapted to switch resistance in response to predetermined voltage values applied between the top electrode and the bottom electrode. Each memristor is operatively connected to an output terminal by means of its bottom electrode. A control logic is connected to the memristors for applying suitable voltages necessary to determine a change of resistance in at least one memristor of the pair.

A cryptographic device includes: a data input; a data output; a cipher circuit configured to perform a cipher algorithm on cipher-algorithm input data to produce cipher-algorithm output data; and a network coupled to the data input, the data output, and the cipher circuit, the network comprising a plurality of switches and a plurality of logical signal combiners that are configured to provide the cipher-algorithm input data to the cipher circuit and to provide device output data to the data output using the cipher-algorithm output data and that, in combination with the cipher circuit, are configured to implement a plurality of different cryptographic algorithms that each include the cipher algorithm that the cipher circuit is configured to perform.

A registration apparatus generates shares by secret sharing of a character string with a plurality of modulus and sends the shares to a plurality of server apparatuses to be stored therein. A retrieval apparatus sends shares generated by secret sharing of a retrieval character string with the plurality of modulus to the plurality of server apparatuses. The plurality of server apparatuses execute a subroutine for shares of the each registration character string stored in a storage unit and for each of the plurality of modulus, reconstruct an execution result, and determine whether or not to return the shares of the registration character string stored in the storage unit as a retrieval result. A retrieval apparatus reconstructs shares returned from the plurality of server apparatuses and obtains a retrieval result in which the retrieval character string hits, from the reconstructed result by the Chinese remainder theorem.

A plaintext encryption method comprising the steps of converting plaintext (20) into information (18) capable of representing visual information! and producing at least two random codes (14A, 14B, 14C), wherein combination thereof equals the information (18) capable of representing visual information, thereby encrypting the plaintext (20) to the random codes (14A, 14B, 14C).

A plaintext encryption method comprising the steps of converting plaintext (20) into information (18) capable of representing visual information! and producing at least two random codes (14A, 14B, 14C), wherein combination thereof equals the information (18) capable of representing visual information, thereby encrypting the plaintext (20) to the random codes (14A, 14B, 14C).