Design of low area-overhead ring oscillator PUF with large challenge space

Exorbitantly high resource-overhead is an important limiting factor for designing a Ring Oscillator Physically Unclonable Function (ROPUF) with large challenge-space. This work presents a design approach for large ROPUF with much lesser resource than that required for classical ROPUF design. It exploits small ROPUFs as design building blocks. Quality of the proposed scheme has been validated by the design of 60-bit ROPUF on Altera FPGA (Field Programmable Gate Array) that is physically infeasible according to previously proposed direct design principles. The hardware resource required for the 60-bit proposed ROPUF design is lesser than that for 10-bit classic ROPUF. In addition, implementation of 60-bit proposed ROPUF shows 47% uniqueness and 91 % reliability on average.