Two kinds of contemporary developments in cryptography are examined. Widening applications of teleprocessing have given rise to a need for new types of cryptographic systems, which minimize the need for secure key distribution channels and supply the equivalent of a written signature. This paper suggests ways to solve these currently open problems. It also discusses how the theories of communication and computation are beginning to provide the tools to solve cryptographic problems of long standing.

A digital home network is a cluster of digital audio/visual (A/V) devices including set-top boxes, TVs, VCRs, DVD players, and general-purpose computing devices such as personal computers. The network may receive copyrighted digital multimedia content from a number of sources. This content may be broadcast via satellite or terrestrial systems, transmitted by cable operators, or made available as prepackaged media (e.g., a digital tape or a digital video disc). Before releasing their content for distribution, the content owners may require protection by specifying access conditions. Once the content is delivered to the consumer, it moves across home the network until it reaches its destination where it is stored or displayed. A copy protection system is needed to prevent unauthorized access to bit streams in transmission from one A/V device to another or while it is in storage on magnetic or optical media. Recently, two fundamental groups of technologies, encryption and watermarking, have been identified for protecting copyrighted digital multimedia content. This paper is an overview of the work done for protecting content owners’ investment in intellectual property.

Double encryption has been suggested to strengthen the Federal Data Encryption Standard (DES). A recent proposal suggests that using two 56-bit keys but enciphering 3 times (encrypt with a first key, decrypt with a second key, then encrypt with the first key again) increases security over simple double encryption. This paper shows that although either technique significantly improves security over single encryption, the new technique does not significantly increase security over simple double encryption. Cryptanalysis of the 112-bit key requires about 2^56 operations and words of memory, using a chosen plaintext attack. While DES is used as an example, the technique is applicable to any similar cipher.

The Shannon theory of cipher systems is combined with recent work on guessing values of random variables. The security of encryption systems is measured in terms of moments of the number of guesses needed for the wiretapper to uncover the plaintext given the cryptogram. While the encrypter aims at maximizing the guessing effort, the wiretapper strives to minimize it, e.g., by ordering guesses according to descending order of posterior probabilities of plaintexts given the cryptogram. For a memoryless plaintext source and a given key rate, a single-letter characterization is given for the highest achievable guessing exponent function, that is, the exponential rate of the ae- th moment of the number of guesses as a function of the plaintext message length. Moreover, we demonstrate asymptotically optimal strategies for both encryption and guessing, which are universal in the sense of being independent of the statistics of the source. The guessing exponent is then investigated as a functi...

SplitPath is a new application for the easy, well-known and provably secure One-time pad encryption scheme. Two problems hinder the One-time pad scheme from being applied in the area of secure data communication: the random generation and the distribution of this random data. SplitPath exploits the flexibility of code mobility in active networks to address these problems. Especially the random generation is studied in more detail. CR Categories and Subject Descriptors: C.2.0 [Computer-Communication Networks]: General; C.2.4 [Computer-CommunicationNetworks]: Distributed Systems; C.2.6 [Computer-Communication Networks]: Internetworking. General Terms: Security, Experimentation. Keywords: Active networking, intelligent networks, code mobility, random generation, one-time pad, cryptography. 3 1 Introduction A wide variety of encryption algorithms is in daily use to protect data communications. Good encryption algorithms base on a complex theoretical foundation, which is somet...

Recent information hiding schemes are scrutinized in terms of their cryptographic performance. We establish conditions under which the key equivocation function is optimal for the studied schemes, and show that, under a reasonable key generation model, the perfect secrecy property is nearly satisfied, limited by a mutual information measure that decreases exponentially with the block length. The novelty of the work is to extend classical cryptographic analysis results to schemes involving cover signals, a component absent from standard cryptography. The schemes show unexpectedly good cryptographic security, although we observe that information embedding with robustness has steganographic weaknesses. Index Terms — Information hiding; wet paper coding; key equivocation; message equivocation; perfect secrecy. 1.

the secure embedding scheme (see Section II), it is hard to generate a watermarked version of c which has a low correlation with k0. An estimation attack usually yields a watermarked object that still correlates well with k0; a judge will reject the accusation on such an object, as it can only originate from a malicious seller (k0 is only available to the seller). • Finally, can attempt to cheat in step 6 by submitting the customer a wrongly encrypted watermark EK (nkw 8 k). However, this is detected by the client in step 7 by checking the integrity of the transaction number contained therein. IV. CONCLUSION In this correspondence, we proposed a buyer–seller protocol that utilizes the concepts of secure watermark embedding. In contrast to the known solutions, which use homomorphic public-key encryption on the content and impose unpractical constraints on computational resources and transmission bandwidth, our protocol is efficient due to the use of recent secure embedding algorithms.

Information theoretic approach for decipherment problems is the recent trend in cryptanalysis. The behavioral transformation of message units is addressed upto certain extent in the encryption process. However the amount of confusion and diffusion in terms of statistical distribution parameters between message and cipher text is a point of interest for cryptanalyst. In the present work we addressed this issue with the help of enhanced probability distribution function. The basic units of any message text are observed to be heuristic in nature depending on the sample. Averaging function is adopted while evaluating the enhanced probabilities of message units. The retrieved efficiency of cipher text only attack on samples of English, Hindi Telugu, Kannada is presented in this paper.

Abstract—Image-scrambling schemes are designed to render the image content unintelligible. Wyner has proposed an elegant one-dimensional (1-D) scrambling scheme without bandwidth expansion, making use of the discrete prolate spheroidal sequences (DPSS). The DPSS are optimal regarding their energy concentration in a given frequency subband. In this paper, we propose the two-dimensional (2-D) extension and application of this algorithm. We discuss new possibilities introduced by the 2-D approach. We also include experimental results. Index Terms—Conditional access, content protection, discrete prolate spheroidal sequences (DPSS), Hadamard matrix, image scrambling, orthogonal transforms. I.