Abstract: The characteristics of fifth-order Fibonacci Lucas sequence were deeply researched, and based on it 5FLELG publirkey cryptosystem and digital signature scheme were presented which replace the Lucas sequence and 3F-L sequence by fifth-order Fibonacci Lucas sequence. The correctness and validity were studied and the fast computational algorithm for evaluating the term of fifth-order Fibonacci-Lucas sequence was given. At last, efficiency and security analysis of the scheme was provided.

Key words: LUCELG, 3F-LELG, Fibonacci-Lucas scqucnce, Public-key cryptosystem