We propose and demonstrate a secure DPSK-based multi-dimensional 216-ary block ciphering system using a multiport encoder/decoder for secure optical fiber transmission. The proposed scheme presents a very high physical-level confidentiality.
We present different optical secure point-to-point transmission schemes using a planar multiport encoder/decoder. We consider both bit- and block-cipher cryptography: in the first case, each bit (both mark and space) from each user is encoded in a two-key optical code-division multiplexing signal. Block-cipher cryptography encodes a stream ofnbits into a single code and corresponds to opticalM-ary transmission. We demonstrate that block-ciphers are more secure with respect to bit-ciphers schemes and also against known-plaintext and chosen-plaintext attacks.
A theoretical model is proposed to analyze the time-domain spectral phase en/decoding and evaluate the unconditional security of the optical code-based secure optical communication systems with DPSK modulation. The confidentiality of the systems with and without bit-by-bit code scrambling technique is investigated. It mathematically proves that the system without code scrambling lacks confidentiality and the system employing code scrambling can realize unconditionally secure transmission. Furthermore, encoding only within the central band of the spectrum is sufficient for perfect secrecy, and the secrecy rate can be potentially improved. It allows the system to operate in the burst mode for code generation and encoding and thus have an idle time for rearm.
A novel implementation of quantum-noise optical cryptography is proposed, which is based on a simplified architecture that allows long-haul, high-speed transmission in a fiber optical network. By using a single multiport encoder/decoder and 16 phase shifters, this new approach can provide the same confidentiality as other implementations of Yuen's encryption protocol, which use a larger number of phase or polarization coherent states. Data confidentiality and error probability for authorized and unauthorized receivers are carefully analyzed.
In this paper, we review the recent advances and demonstrations of time domain pseudorandom optical phase encoding technology for high speed 40Gb/s OOK and DPSK secure optical communication systems. Bit-by-bit code shifting technique for enhancing the information security is proposed and demonstrated in different optical transmission systems with various bit rates and modulation formats. The potential application of the proposed techniques for high speed secure optical transmission systems is envisioned.
In this letter, the information security of an optical code-based communication system employing orthogonal differential phase-shift keying (DPSK)/code-shift keying (CSK) modulation is first investigated using two eaves dropping methods, one-bit delay interference detection and differential detection. The investigation results show that the security vulnerability exists only in the CSK channel while the DPSK channel can thwart these attacks. Therefore, the concept of public-key cryptography is introduced into the system to efficiently use these two orthogonal channels for both public key distribution and encrypted data transmission. The privacy of the transmitted data can be double guaranteed by public-key cryptography scheme logically and optical code-processing techniques physically.