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Statistical Techniques for Language Recognition: An Introduction and Guide for Cryptanalysts
 Cryptologia
, 1993
"... We explain how to apply statistical techniques to solve several languagerecognition problems that arise in cryptanalysis and other domains. Language recognition is important in cryptanalysis because, among other applications, an exhaustive key search of any cryptosystem from ciphertext alone requir ..."
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Cited by 11 (2 self)
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We explain how to apply statistical techniques to solve several languagerecognition problems that arise in cryptanalysis and other domains. Language recognition is important in cryptanalysis because, among other applications, an exhaustive key search of any cryptosystem from ciphertext alone requires a test that recognizes valid plaintext. Written for cryptanalysts, this guide should also be helpful to others as an introduction to statistical inference on Markov chains. Modeling language as a finite stationary Markov process, we adapt a statistical model of pattern recognition to language recognition. Within this framework we consider four welldefined languagerecognition problems: 1) recognizing a known language, 2) distinguishing a known language from uniform noise, 3) distinguishing unknown 0thorder noise from unknown 1storder language, and 4) detecting nonuniform unknown language. For the second problem we give a most powerful test based on the NeymanPearson Lemma. For the oth...
On the Properties of Pseudo Noise Sequences with a Simple Proposal of Randomness Test
"... Abstract—Maximal length sequences (msequences) are also known as pseudo random sequences or pseudo noise sequences for closely following Golomb’s popular randomness properties: (P1) balance, (P2) run, and (P3) ideal autocorrelation. Apart from these, there also exist certain other less known proper ..."
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Abstract—Maximal length sequences (msequences) are also known as pseudo random sequences or pseudo noise sequences for closely following Golomb’s popular randomness properties: (P1) balance, (P2) run, and (P3) ideal autocorrelation. Apart from these, there also exist certain other less known properties of such sequences all of which are discussed in this tutorial paper. Comprehensive proofs to each of these properties are provided towards better understanding of such sequences. A simple test is also proposed at the end of the paper in order to distinguish pseudo noise sequences from truly random sequences such as Bernoulli sequences. Keywords—Maximal length sequence, pseudo noise sequence, punctured de Bruijn sequence, autocorrelation, Bernoulli sequence, randomness tests. I.
Is the Data Encryption Standard a Group? (Results of Cycling Experiments on DES)I
"... Abstract. The Data Encryption Standard (DES) defines an indexed set of permutations acting on the message space ~ = {0, 1} 64. If this set of permutations were closed under functional composition, then the two most popular proposals for strengthening DES through multiple encryption would be equival ..."
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Abstract. The Data Encryption Standard (DES) defines an indexed set of permutations acting on the message space ~ = {0, 1} 64. If this set of permutations were closed under functional composition, then the two most popular proposals for strengthening DES through multiple encryption would be equivalent to single encryption. Moreover, DES would be vulnerable to a knownplaintext attack that runs in 22s steps on the average. It is unknown in the open literature whether or not DES has this weakness. Two statistical tests are presented for determining if an indexed set of permutations acting on a finite message space forms a group under functional composition. The first test is a "meetinthemiddle " algorithm which uses O(v/K) time and space, where K is the size of the key space. The second test, a novel cycling algorithm, uses the same amount of time but only a small constant amount of space. Each test yields a knownplaintext attack against any finite, deterministic cryptosystem that generates a small group. The cycling closure test takes a pseudorandom walk in the message space until
International Journal of Electrical and Computer Engineering 3:3 2008 On the Properties of Pseudo Noise Sequences with a Simple Proposal of Randomness Test
"... Abstract—Maximal length sequences (msequences) are also known as pseudo random sequences or pseudo noise sequences for closely following Golomb’s popular randomness properties: (P1) balance, (P2) run, and (P3) ideal autocorrelation. Apart from these, there also exist certain other less known proper ..."
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Abstract—Maximal length sequences (msequences) are also known as pseudo random sequences or pseudo noise sequences for closely following Golomb’s popular randomness properties: (P1) balance, (P2) run, and (P3) ideal autocorrelation. Apart from these, there also exist certain other less known properties of such sequences all of which are discussed in this tutorial paper. Comprehensive proofs to each of these properties are provided towards better understanding of such sequences. A simple test is also proposed at the end of the paper in order to distinguish pseudo noise sequences from truly random sequences such as Bernoulli sequences. Keywords—Maximal length sequence, pseudo noise sequence, punctured de Bruijn sequence, autocorrelation, Bernoulli sequence, randomness tests. I.
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"... The literature of cryptography has a curious history. Secrecy, of course, has always played a central role, but until the First World War, important developments appeared in print in a more or less timely fashion and the field moved forward in much the same way as other specialized disciplines. As l ..."
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The literature of cryptography has a curious history. Secrecy, of course, has always played a central role, but until the First World War, important developments appeared in print in a more or less timely fashion and the field moved forward in much the same way as other specialized disciplines. As late as 1918, one of the most influential cryptanalytic papers of the twentieth century, William F. Friedman’s monograph The Index of Coincidence and Its Applications in Cryptography, appeared as a research report of the private Riverbank Laboratories [577]. And this, despite the fact that the work had been done as part of the war effort. In the same year Edward H. Hebern of Oakland, California filed the first patent for a rotor machine [710], the device destined to be a mainstay of military cryptography for nearly 50 years. After the First World War, however, things began to change. U.S. Army and Navy organizations, working entirely in secret, began to make fundamental advances in cryptography. During the thirties and forties a few basic papers did appear in the open literature and several treatises on the subject were published, but the latter were farther and farther behind the state of the art. By the end of the war the transition was complete. With one notable exception, the public literature had died. That exception was Claude Shannon’s paper “The Communication Theory of Secrecy Systems, ” which