Flash memory device, flash memory system, and methods of operating the same

A method of preventing physical cloning by using a flash memory, comprising:

• transmitting, by a source external to the flash memory, an authentication challenge to the flash memory;
• selecting memory cells of the flash memory based on the authentication challenge;
• programming pieces of same input data into each of the selected memory cells;
• reading the selected memory cells to generate control information;
• dividing the selective memory cells into at least one first region memory cell and at least one second memory cell based on the control information;
• setting read values of the at least one first region memory cell and the at least one second region memory cell to a first value and a second value, respectively, based on the control information;
• and
• generating an authentication response in the response to the authentication challenge based on the set values.

A method of operating a flash memory system, comprising:

• selecting, by a controller of the system, memory cells of a flash memory of the system in response to an authentication challenge;
• programming, by the controller, data into the selected memory cells;
• reading, by the controller, the selected memory cells multiple times to generate a history of read values;
• determining, by the controller, which of the selected memory cells have a constant value and a variable value based on the generated history;
• setting, by the controller, a first value for each memory cell determined to have the constant value to a value from the corresponding memory cell;
• setting, by the controller, a second value for each memory cell determined to have the variable value to a constant value;
• and
• generating, by the controller, an authentication response comprising the first values and the second values.