apparatus 200 are connected to each other via a communications line 300 fig2 is a diagram for illustrating the inner configuration of the sender side apparatus 100 in each embodiment the sender side apparatus 100 includes a random number generation unit 101 a power multiplication unit 102 an arithmetic operation unit 103 a remainder arithmetic operation unit 104 a memory 105 a communications apparatus 106 an input apparatus 107 and an encryption unit 108 fig3 is a diagram for illustrating the inner configuration of the receiver side apparatus 200 in each embodiment the receiver side apparatus 200 includes a key generation unit 201 a power multiplication unit 202 a remainder arithmetic operation unit 203 an arithmetic operation unit 204 a memory 205 a communications apparatus 206 and a decryption unit 207 the above described sender side apparatus or receiver side apparatus can be embodied using a common computer including a cpu and a memory furthermore the cpu executes on the memory programs stored in a fixed storage apparatus included in the above described computer thereby making it possible to embody the random number generation unit 101 the power multiplication units 102 202 the arithmetic operation units 103 204 the remainder arithmetic operation units 104 203 the encryption unit 108 the key generation unit 201 and the decryption unit 207 the respective programs may be stored into the fixed storage apparatus in advance or may be installed into the fixed storage apparatus or the.