Pseudo physically unclonable functions (PUFS) using one or more addressable arrays of elements having random/pseudo-random values
An integrated circuit device can include a plurality of nonvolatile memory elements having values that vary randomly or pseudo-randomly from one another; a selection circuit configured to select a plurality of nonvolatile memory elements that vary randomly or pseudo-randomly in response to a received challenge value; and sense circuits configured to generate a response value based on the values of the selected nonvolatile memory elements. Related methods and systems are also disclosed.
1. A method, comprising:
applying forming electrical conditions to at least some of a plurality of programmable resistive elements of a hash array to create a resistance distribution in the elements that varies according to at least manufacturing variations in the elements;
forming a physically unclonable function (PUF) array of essentially random values from the resistive elements of the hash array based on the resistance distribution of the elements, including
determining a logic state of at least some of the elements of the hash array based on the resistance of the elements of the hash array, and
copying the logic states of the elements of the hash array to memory cells of at least one memory array to form the PUF array; and
applying binary challenge values to the PUF array to select a plurality of the random values.
2. The method of claim 1 , wherein:
applying the forming electrical conditions is selected from the group of: applying electrical conditions to newly manufactured elements; and applying electrical conditions to elements set to one resistance state that tend to shift the elements to another resistance state.
3. The method of claim 1 , wherein:
the logic state of the elements comprises m-bits; and
copying the logic state includes writing n-bits into the memory cells of the at least one memory array for each m-bits of the hash array;
m and n are at least one; and
n is selected form a value equal to, less than, or greater than m.
4. The method of claim 1 , wherein:
the memory cells of the PUF array also include programmable resistive memory elements.
5. The method of claim 1 , wherein:
the hash array has a location selected from: a same memory cell array as the PUF array; a different memory cells array than the PUF array; a same integrated circuit device as the PUF array; and a different integrated circuit device than the PUF array.
6. The method of claim 1 , wherein:
copying the logic states of the hash array elements includes copying the logic states of the hash array to a plurality of other memory circuits to form a plurality of PUF arrays.
7. The method of claim 1 , wherein:
applying the forming electrical conditions includes
sensing a resistance of memory element
if the sensed resistance is in a one range, applying the forming conditions to the element, and
if the sensed resistance is in another range, not applying the forming conditions to the element.