Authentication apparatus, authentication method and program for generating a challenge in accordance with a state of challenge-response authentication with a client terminal
An authentication apparatus that performs authentication of a client terminal by challenge-response authentication, the authentication apparatus includes one or more computers each including a memory and a processor configured to: receive a challenge request from the client terminal; generate a challenge as to the challenge request; and transmit the challenge to the client terminal. The memory and the processor are configured to generate the challenge by one generating method out of a fixed generating method in which a challenge of a fixed value is generated, and a random generating method in which a challenge of a random value is generated, in accordance with a state of the authentication apparatus.
1. An authentication apparatus that performs authentication of a client terminal by challenge-response authentication, the authentication apparatus comprising:
one or more computers each including a memory and a processor configured to:
receive a challenge request from the client terminal;
generate a challenge as to the challenge request; and
transmit the challenge to the client terminal, wherein
the memory and the processor are configured to generate the challenge by one generating method out of a fixed generating method in which a challenge of a fixed value is generated, and a random generating method in which a challenge of a random value is generated, in accordance with a state of challenge-response authentication with the client terminal.
2. The authentication apparatus according to claim 1 , wherein
in a case where the authentication apparatus is in a state of having received a challenge request from the client terminal for the first time, or in a case where the authentication apparatus is in a state of having received a challenge request from the client terminal for the first time after receiving a response by which authentication fails, the memory and the processor are further configured to generate the challenge by the random generating method.
3. The authentication apparatus according to claim 1 , wherein
in a case where the authentication apparatus is in a state of having received a challenge request from the client terminal for a second time or having received a challenge request from the client terminal following the second time before receiving a response, the memory and the processor are further configured to generate the challenge by the fixed generating method.
4. The authentication apparatus according to claim 1 , wherein
in a case where the memory and the processor receive a response, authentication by the response fails, and a number of times of an authentication failure reaches a predetermined allowed count, the memory and the processor are configured not transmit a challenge to the client terminal even in a case where the memory and the processor receive a challenge request from the client terminal.
5. An authentication method executed by an authentication apparatus that performs authentication of a client terminal by challenge-response authentication, the authentication method comprising:
receiving a challenge request from the client terminal;
generating a challenge as to the challenge request; and
transmitting the challenge to the client terminal, wherein
the challenge is generated by one generating method out of a fixed generating method in which a challenge of a fixed value is generated, and a random generating method in which a challenge of a random value is generated, in accordance with a state of challenge-response authentication with the client terminal.
6. A non-transitory computer-readable recording medium having computer-readable instructions stored thereon, which when executed cause a computer including a memory and a processor to execute each of operations of the authentication apparatus according to claim 1 .