Achieving Physical Layer Security / Privacy with Self-Wrapped OCDM Transmission
ABSTRACT We present a novel transmission system using self-wrapped WHTS OCDM signals to achieve enhanced transmission security. Distributed key is encoded and time-spread to hide under noise in the network. BER of 10-4 is demonstrated experimentally.
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ABSTRACT: A new technique for encoding and decoding of coherent ultrashort light pulses is analyzed. In particular, the temporal and statistical behavior of pseudonoise bursts generated by spectral phase coding of ultrashort optical pulses is discussed. the analysis is motivated by recent experiments that demonstrate high-resolution spectral phase coding of picosecond and femtosecond pulses and suggest the possibility of ultrahigh speed code-division multiple-access (CDMA) communications using this technique. The evolution of coherent ultrashort pulses into low intensity pseudonoise bursts as a function of the degree of phase coding is traced. The results are utilized to analyze the performance of a proposed CDMA optical communications system based upon encoding and decoding of ultrashort light pulses. The bit error rate (BER) is derived as a function of data rate, number of users, and receiver threshold, and the performance characteristics are discussed for a variety of system parameters. It is found that performance improves greatly with increasing code lengthJournal of Lightwave Technology 04/1990; · 2.56 Impact Factor
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ABSTRACT: Recently, there has been a renewed interest in optical code-division multiple access (OCDMA) due to its potential for offering increased levels of security at ultrahigh data rates as well as for simplifying key networking functions, such as replacing (active) wavelength translation with cascaded passive all-optical code translation (CT). Much of the research done in this area has focused on homogeneous OCDMA networking, where it is assumed that the fiber bandwidth is used only for OCDMA signals. In contrast to other proposed OCDMA systems, we have developed a novel narrowband (NB) spectrally phase-encoded (SPE) OCDMA that is compatible with existing transparent reconfigurable dense-WDM (DWDM) networks and has high spectral efficiency. In this paper, we experimentally demonstrate, for the first time, the feasibility of multistage CT in the proposed WDM-compatible SPE OCDMA system, and we also describe how cascaded CTs can play a central role in ring- and star-network architectures. Specifically, we describe a star-network architecture in which both unicast and multicast interconnections among ends are passively "routed" by means of such cascaded CTs, a ring-network architecture in which CT and fast optical switching enable a code-based equivalent to add/drop wavelength multiplexing, and a shared code-scrambling application for increased signal obscurity.Journal of Lightwave Technology 11/2005; 23(10):3219- 3231. · 2.56 Impact Factor
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ABSTRACT: An information-theoretic analysis of information hiding is presented, forming the theoretical basis for design of information-hiding systems. Information hiding is an emerging research area which encompasses applications such as copyright protection for digital media, watermarking, fingerprinting, steganography, and data embedding. In these applications, information is hidden within a host data set and is to be reliably communicated to a receiver. The host data set is intentionally corrupted, but in a covert way, designed to be imperceptible to a casual analysis. Next, an attacker may seek to destroy this hidden information, and for this purpose, introduce additional distortion to the data set. Side information (in the form of cryptographic keys and/or information about the host signal) may be available to the information hider and to the decoder. We formalize these notions and evaluate the hiding capacity, which upper-bounds the rates of reliable transmission and quantifies the fundamental tradeoff between three quantities: the achievable information-hiding rates and the allowed distortion levels for the information hider and the attacker. The hiding capacity is the value of a game between the information hider and the attacker. The optimal attack strategy is the solution of a particular rate-distortion problem, and the optimal hiding strategy is the solution to a channel-coding problem. The hiding capacity is derived by extending the Gel'fand-Pinsker (1980) theory of communication with side information at the encoder. The extensions include the presence of distortion constraints, side information at the decoder, and unknown communication channel. Explicit formulas for capacity are given in several cases, including Bernoulli and Gaussian problems, as well as the important special case of small distortions. In some cases, including the last two above, the hiding capacity is the same whether or not the decoder knows the host data set. It is shown that many existing information-hiding systems in the literature operate far below capacity.IEEE Transactions on Information Theory 04/2003; · 2.62 Impact Factor