Authentication device, authentication system, authentication method, and program

An authentication device comprising:

• a storage that stores a common key;
• a first output unit that outputs a first challenge value corresponding to a random number along with a first authentication request;
• a second input unit to which a plurality of second challenge values are input along with a second authentication request;
• a first input unit to which a plurality of first response values are input;
• a second output unit that outputs a plurality of second response values which are obtained by encrypting a value corresponding to each of the plurality of second challenge values by using the common key by a symmetric key cryptosystem;
• and
• a decision unit that decides whether or not a decrypting result which is obtained by decrypting each of the plurality of first response values by using the common key and a value corresponding to the first challenge value coincide with each other.

An authentication system comprising:

• a first authentication device;
• and
• a second authentication device, wherein
• the first authentication device includes
• a first storage that stores a common key, and
• a first output unit that outputs a first challenge value corresponding to a first random number along with a first authentication request,
• the second authentication device includes
• a second storage that stores the common key, and
• a second output unit that outputs a second challenge value corresponding to a second random number along with a second authentication request,
• the first authentication device includes
• a second input unit to which the second challenge value is input along with the second authentication request, and
• a third output unit that outputs a second response value which is obtained by encrypting a value corresponding to the second challenge value by using the common key by a symmetric key cryptosystem,
• the second authentication device includes
• a third input unit to which the first challenge value is input along with the first authentication request, and
• a fourth output unit that outputs a first response value which is obtained by encrypting a value corresponding to the first challenge value by using the common key by the symmetric key cryptosystem,
• the first authentication device includes
• a first input unit to which the first response value is input, and
• a first decision unit that decides whether or not a first decrypting result which is obtained by decrypting the first response value by using the common key and the value corresponding to the first challenge value coincide with each other, and
• the second authentication device includes
• a fourth input unit to which the second response value is input, and
• a second decision unit that decides whether or not a second decrypting result which is obtained by decrypting the second response value by using the common key and the value corresponding to the second challenge value coincide with each other.

An authentication method comprising:

• a step in which a first output unit outputs a first challenge value corresponding to a random number along with a first authentication request;
• a step in which a second challenge value is input to a second input unit along with a second authentication request;
• a step in which a first response value is input to a first input unit;
• a step in which a second output unit outputs a second response value which is obtained by encrypting a value corresponding to the second challenge value by using a common key, which is stored in a storage, by a symmetric key cryptosystem;
• and
• a step in which a decision unit decides whether or not a decrypting result which is obtained by decrypting the first response value by using the common key and a value corresponding to the first challenge value coincide with each other.