The invention discloses an RO PUF 
key generation method based on a tetrad comparison strategy, and the method comprises the steps: obtaining the oscillation frequency of a 
ring oscillator sequence through constructing the 
ring oscillator sequence, and storing the oscillation frequency; dividing the 
ring oscillator sequence into a plurality of ring oscillator quaternions, performing pairwise non-repetitive 
pairing to obtain ring oscillator comparison pairs in the 
pairing mode, calculating the sum of absolute values between oscillation frequency differences of the comparison pairs, selecting the comparison pair corresponding to the maximum value as the optimal 
pairing mode, storing the position information and the oscillation frequency information of the comparison pair in a ring oscillator comparison 
library; judging ring oscillator comparison pairs in the ring oscillator comparison 
library through input excitation, generating key bit numbers, and combining the key bit numbers into keys with different bit lengths. According to the 
key generation method, the problem of poor response stability in generation of the 
physical unclonable function based on the annular oscillator is solved, and the 
key generation method which is higher in anti-interference power, higher in stability, 
safer, more effective and low in complexity is provided.