Secure Optical Communications Based on Fast Cryptography

Although security solutions, like Advanced Encryption Standard (AES) and ChaCha, are common at the packet layer, secure transmission at the optical layer is still not implemented. The reason is that such cryptographic methods are not fast enough to support high-speed optical transmission and might introduce significant delay. Moreover, methods for key exchange, key generation and key expansion need to be implemented on standard coherent transponders. In this paper, we summarize a secure cryptographic solution for optical connections named Light Path SECurity (LPsec), which involves fast data encryption using stream ciphers and key exchange using Diffie-Hellman (DH) protocol through the optical channel. To support encryption of high-speed data streams, a fast, general purpose Pseudo-Random Number Generator (PRNG) is used. Moreover, to make the scheme more secure against exhaustive search attacks, an additional substitution cipher is proposed. In contrast to the limited encryption speeds that standard stream ciphers can support, LPsec can support high-speed rates.