Research of hash-based secure key expansion algorithm for practical QKD

The quantum key distribution (QKD) system has been developed rapidly, but its key generation rate is limited for kinds of reason such as detector efficiency and not fitted for high speed application such as video conferences. For promotion of key generation rate, an algorithm based secure hash algorithm (SHA) is introduced to process QKD keys which could be expanded to be about tens times and implemented in field programmable gate array (FPGA) device in this paper. The expanded key is tested by NIST test program to verify its randomness and security. In our tests, the expanded keys less than 32 times QKD keys are all passed NIST test program and shows its good security.