Abstract: Key expansion is an efficient way for quantum noise random stream cipher (QNRC) to use quantum key distribution（QKD）keys. Generally, the classical encryption methods are often used for key expansion in QNRC experiments, such as advanced encryption standard (AES) and Hash algorithms, because of their difficulty in deciphering. According to the working mode of block cipher, the Hash expansion schemes of counter (CTR) and cipher block link (CBC) mode are reasonably designed. Moreover, NIST random test is implemented on the running key streams generated under different expansion schemes. The test results show that AES and Hash expansion schemes both in CTR and CBC modes can pass the test of randomicity. Especially for the Hash expansion in CTR mode, the input length of which can be flexibly controlled, so it can better adapt to different requirements of modern high-speed optical network.

Key words: key expansion, quantum noise random stream cipher, Hash algorithm, counter mode, cipher block link mode