Electronic circuit, electronic apparatus, and authentication system

An electronic apparatus comprising:

• a random number generator configured to include
• a plurality of RS latch circuits each configured to enter a metastable state in accordance with a clock signal input to the RS latch circuit,
• a determination circuit configured to determine whether an output of each of the RS latch circuits is a random number or a fixed number,
• a selector configured to
• maintain the clock signal input to the RS latch circuit if it is determined that the output of the RS latch circuit is a random number,
• change the clock signal input to the RS latch circuit to another clock signal having a different frequency if it is determined that the output of the RS latch circuit is a fixed number, and
• input a signal for fixing a signal output from the RS latch circuit if it is determined that the output of the RS latch circuit is a fixed number even when any clock signal having a different frequency is input, and
• an exclusive OR circuit configured to calculate an exclusive OR of outputs of the RS latch circuits;
• and
• a cryptography processor configured to perform an encryption process and a decryption process by using a random number generated by the random number generator as an encryption key.

An electronic apparatus comprising:

• a plurality of RS latch circuits each configured to enter a metastable state in accordance with a clock signal input to the RS latch circuit;
• a determination circuit configured to determine whether an output of each of the RS latch circuits is a random number or a fixed number;
• a selector configured to
• maintain the clock signal input to the RS latch circuit if it is determined that the output of the RS latch circuit is a fixed number,
• change the clock signal input to the RS latch circuit to another clock signal having a different frequency if it is determined that the output of the RS latch circuit is a random number, and
• input a signal for fixing a signal output from the RS latch circuit if it is determined that the output of the RS latch circuit is a random number even when any clock signal having a different frequency is input;
• an individual-specific information generation unit configured to generate an individual-specific information using outputs of the plurality of RS latch circuits;
• and
• a cryptography processor configured to perform an encryption process and a decryption process by using the individual-specific information generated by the individual-specific information generation unit as an encryption key.

An authentication system comprising:

• an electronic apparatus configured to include
• a plurality of RS latch circuits each configured to enter a metastable state in accordance with a clock signal input to the RS latch circuit,
• a determination circuit configured to determine whether an output of each of the RS latch circuits is a random number or a fixed number,
• a selector configured to
• maintain the clock signal input to the RS latch circuit if it is determined that the output of the RS latch circuit is a fixed number,
• change the clock signal input to the RS latch circuit to another clock signal having a different frequency if it is determined that the output of the RS latch circuit is a random number, and
• input a signal for fixing a signal output from the RS latch circuit if it is determined that the output of the RS latch circuit is a random number even when any clock signal having a different frequency is input,
• an individual-specific information generation unit configured to generate an individual-specific information using outputs of the plurality of RS latch circuits, and
• a communication unit configured to send the individual-specific information generated by the individual-specific information generation unit;
• and
• an authentication apparatus configured to authenticate the individual-specific information sent form the electronic apparatus.