Highly secure key accompanying transmission scheme with key camouflaging based on hash-assisted dual-chaotic encryption

The paper proposes a highly secure key accompanying transmission scheme with key camouflaging based on hash-assisted dual-chaotic encryption. The two chaotic systems employed are the Rossler chaotic system (RCS) and the Chua chaotic system (CCS). By applying bit noise masking followed by an XOR operation with a hash sequence generated by a hash function, the key of CCS is effectively camouflaged. The camouflaged key is then transmitted using the training sequence (TS). This paper defines a joint scrambling degree (JSD) as an indicator to measure the concealment level of the CCS's key, which is 23.33 in the proposed scheme, ensuring the security of the CCS's key. The scheme is experimentally validated in a 2 km 7-core fiber, transmitting encrypted signals at a rate of 54.25 Gb/s. A comparison of the bit error rate (BER) between the encrypted signal, unencrypted signal, and signal intercepted by illegal receivers demonstrates that the encryption scheme guarantees transmission security while having no impact on system performance. The BER curve of the encrypted data meets the 3.8 × 10^-3 threshold for 7% hard-decision forward error correction (HD-FEC). This scheme used a hash function to camouflage the key, ensuring its security during transmission. Meanwhile, the use of chaotic cascade expands the key space, resulting in a system key space of 10²⁴⁰, which effectively resists brute-force attacks.