To acquire unique and random keys for chips from PUF, key extraction schemes for SRAM PUF are introduced. These schemes include the hard-decision and soft-decision decoding ones involving concatenated error-correcting code. By the actual responses of SRAM PUF’s on chips and software simulation, the effect of above two schemes is verified. The result shows that, for SRAM PUF, the soft-decision scheme is more reliable and efficient.