Random number generator for defending against subchannel attack, and operation method thereof

A method for operating a random frequency clock generator resistant to side-channel attacks, the method comprising:

• (a) generating random pulses by an entropy unit;
• (b) generating random frequencies by receiving random pulses output from the entropy unit;
• and
• (c) masking a predetermined instruction externally by a microcontroller unit (MCU) based on a random frequency received from the random frequency clock generator,
• wherein
• when the predetermined instruction is not executed, the MCU selectively receives a reference clock, and
• when the predetermined instruction is executed, the MCU selectively receives the random frequency from the random frequency clock generator in order to externally hide the predetermined operation or the predetermined instruction.

A random number generator resistant to side-channel attacks, the random number generator comprising:

• an entropy unit generating random pulses;
• a random frequency clock generator generating random frequencies by receiving random pulses output from the entropy unit;
• a microcontroller unit (MCU) externally masking a predetermined operation or a predetermined instruction based on a random frequency received from the random frequency clock generator;
• a first selector selectively outputting the random frequency output from the random frequency clock generator and a reference clock to the MCU according to a first selection signal;
• a counter outputting a first random number based on a random pulse output from the entropy unit;
• and
• a second selector selectively outputting one of a random number output from a second random bit generator and the first random number output from the counter according to a second selection signal,
• wherein
• the random frequency output from the random frequency clock generator is used to implement a hiding technique, which is a countermeasure against a side-channel attack, and
• the random number output from the second selector is used to implement a masking technique, which is a countermeasure against a side-channel attack.