774 research outputs found
How Fast can be Algebraic Attacks on Block Ciphers?
No full textIn this paper we give a specification of a new block cipher that can be called the Courtois Toy Cipher (CTC). It is quite simple, and yet very much like any other known block cipher. If the parameters are large enough, it should evidently be secure against all known attack methods.However, we are not proposing a new method for encrypting sensitive data, but rather a research tool that should allow us (and other researchers) to experiment with algebraic attacks on block ciphers and obtain interesting results using a PC with reasonable quantity of RAM. For this reason the S-box of this cipher has only 3-bits, which is quite small. Ciphers wit
Images d’un témoin disparu. Le manuscrit Rothschild (X) du Guiron le Courtois
No full textLeonardi Lino, Morato Nicolas, Molteni Ilaria. Images d’un témoin disparu. Le manuscrit Rothschild (X) du Guiron le Courtois. In: Romania, tome 132 n°527-528, 2014. pp. 283-352
Courtois Stéphane, Werth Nicolas, Panné Jean-Louis, Paczkowski Andrzej, Bartosek Karel, Margolin Jean-Louis, Le Livre noir du communisme. Crimes, terreur, répression
No full textBecker Jean-Jacques. Courtois Stéphane, Werth Nicolas, Panné Jean-Louis, Paczkowski Andrzej, Bartosek Karel, Margolin Jean-Louis, Le Livre noir du communisme. Crimes, terreur, répression. In: Vingtième Siècle, revue d'histoire, n°59, juillet-septembre 1998. pp. 177-179
Random Permutation Statistics and An Improved Slide-Determine Attack on KeeLoq
No full textKeeLoq is a lightweight block cipher which is extensively used in the automotive industry. Its periodic structure, and overall simplicity makes it vulnerable to many different attacks. Only certain attacks are considered as really "practical" attacks on KeeLoq: the brute force, and several other attacks which require up to 2p16 known plaintexts and are then much faster than brute force, developed by Courtois et al., and (faster attack) by Dunkelman et al. On the other hand, due to the unusually small block size, there are yet many other attacks on KeeLoq, which require the knowledge of as much as about 2p32 known plaintexts but are much faster still. There are many scenarios in which such attacks are of practical interest, for example if a master key can be recovered, see Section 2 in [11] for a detailed discussion. The fastest of these attacks is an attack by Courtois, Bard and Wagner from that has a very low complexity of about 2p28 KeeLoq encryptions on average. In this paper we will propose an improved and refined attack which is faster both on average and in the best case. We also present an exact mathematical analysis of probabilities that arise in these attacks using the methods of modern analytic combinatorics
Les inconvénients pour la sécurité routière de certains comportements de conduite courtois
No full textJean-Yves Fournier et Nicolas Clabaux (IFSTTAR) La courtoisie au volant est généralement considérée comme porteuse de sécurité. À ce titre, elle fait l’objet de nombreuses campagnes de sensibilisation visant à promouvoir des comportements de conduite plus courtois entre usagers de la route. Il n’y a pourtant pas de travaux scientifiques traitant spécifiquement des liens entre comportements de conduite courtois et production d’accidents. Les travaux existants s’intéressent plutôt aux liens ent..
Les inconvénients pour la sécurité routière de certains comportements de conduite courtois
No full textJean-Yves Fournier et Nicolas Clabaux (IFSTTAR) La courtoisie au volant est généralement considérée comme porteuse de sécurité. À ce titre, elle fait l’objet de nombreuses campagnes de sensibilisation visant à promouvoir des comportements de conduite plus courtois entre usagers de la route. Il n’y a pourtant pas de travaux scientifiques traitant spécifiquement des liens entre comportements de conduite courtois et production d’accidents. Les travaux existants s’intéressent plutôt aux liens ent..
Courtois d’Arras et le Jeu de la Feuillée
No full textThe thirteenth-century secular theatre is particularly interesting insofar as it is a true literary laboratory based on texts with all kinds of plays whose purpose is not always easy to grasp. The introductory masterpiece of this tradition is Jean Bodel’s Jeu de saint Nicolas, written and performed around 1200. In its wake, two works appeared which represent two generations of plays within the thirteenth century : one, Courtois d’Arras, dating from the first quarter of the century, is a subtle variation on the parable of the prodigal son (Luke 15:11-32); in the other, Jeu de la Feuillée, performed on June 3, 1276, Adam de la Halle incorporates his own persona and his entire work, which he uses as subtext. But the two plays have most likely been modeled on the Jeu de St Nicolas, to which they make many allusions. From the start it should be pointed out that the Jeu de la Feuillée is based on the Jeu de St Nicolas, reworked and completed with Courtois d’Arras. In addition, if the latter text is given over to an up-dating of the prodigal son parable and a humanizing of religion as well as to an ironic use of courtoisie, the parody becomes generalized in the Jeu de la Feuillée and ends up totally subverting and destroying all hopes and dreams in a universe where God no longer appears, but where the all-powerful Fortune reigns in irrational and arbitrary triumph. The wheel of Fortune, which never stops turning, has influence over the powerful men of Arras, over the fairies (fées) and finally, more generally, over all the other characters, who come back one by one on the turning wheel which becomes more and more frenetic, each turn bringing a character to the front of the stage, to point out his decline and defeat.Le théâtre profane du XIIIe siècle est pour la littérature un véritable laboratoire. Le chef-d’œuvre inaugural de cette nouvelle tradition est le Jeu de saint Nicolas de Jean Bodel, représenté à Arras vers 1200. Dans son sillage on dénombre deux œuvres qui sont caractéristiques de deux générations du XIIIe siècle. La première, Courtois d’Arras, datant du premier quart de ce siècle, est une subtile variation sur la parabole du fils prodigue. Dans la seconde, le Jeu de la Feuillée, représentée le 3 juin 1276, l’auteur, Adam de la Halle, joue avec son propre personnage et avec l’ensemble de son œuvre qui lui sert d’hypotexte. Mais les deux pièces ont à coup sûr comme modèle le Jeu de saint Nicolas auquel elles font de multiples allusions. Il faut préciser que la Feuillée se situe par rapport à un Jeu de saint Nicolas revu et complété par Courtois d’Arras. D’autre part, si ce texte-ci se livre tout autant à une actualisation de la parabole et à une humanisation de la religion qu’à une utilisation ironique du Conte du Graal et de la courtoisie, la parodie se généralise dans la Feuillée et aboutit à une subversion totale qui détruit tous les espoirs et les rêves dans un univers où Dieu n’apparaît plus, tandis que la toute-puissante roue de Fortune règne et triomphe de façon totalement arbitraire : ne cessant de tourner, elle exerce son influence néfaste sur les puissants d’Arras, sur les fées, sur chacun des personnages de la pièce dont elle détermine le déclin et la défaite
Cryptanalysis of block ciphers with overdefined systems of equations
No full textAbstract. Several recently proposed ciphers are built with layers of small S-boxes, interconnected by linear key-dependent layers. Their security relies on the fact, that the classical methods of cryptanalysis (e.g. linear or differential attacks) are based on probabilistic characteristics, which makes their security grow exponentially with the number of rounds Nr. In this paper we study the security of such ciphers under an additional hypothesis: the S-box can be described by an overdefined system of algebraic equations (true with probability 1). We show that this hypothesis is true for both Serpent (due to a small size of S-boxes) and Rijndael (due to unexpected algebraic properties). We study general methods known for solving overdefined systems of equations, such as XL from Eurocrypt’00, and show their inefficiency. Then we introduce a new method called XSL that uses the sparsity of the equations and their specific structure. The XSL attack has a parameter P, and in theory we show that P should be a constant. The XSL attack would then be polynomial in Nr, with a huge constant that is doubleexponential in the size of the S-box. We demonstrated by computer simulations tha
Dialogue. Isocrate, le prêtre Testis unus et l'abbé Thise ([Reprod.]) / par Alexandre-Nicolas Courtois,...
No full textCollection : Les archives de la Révolution française ; 8.456Collection : Les archives de la Révolution française ; 8.45
"Authorship Theory: The Case Of ""courtois D'arras"" (attribution, Stylistics; Bodel, Jean)"
No full textCourtois d'Arras has long been a subject of controversy among literary historians and philologists, for relatively little is known about its genre, provenance, or date of composition. The question of the work's authorship has aroused particular interest, giving rise to various theories of attribution.This study examines the methodologies traditionally used to investigate the authorship of Courtois d'Arras in the context of a longer discussion of attribution theory in general. We suggest four methodological presuppositions which can contribute to the validity of an attribution argument; these presuppositions include the advantage of studying a series of features rather than a single one, the need for comparative material, the value of comparing all canonical works of the putative author, and the benefits of examining functional, rather than meaningful, textual phenomena. We then incorporate these four premises to design a method of linguistic analysis in order to test a theory ascribing Courtois to Jean Bodel. Courtois d'Arras is compared in terms of the frequency of a series of readily identifiable linguistic features with all of the known works of Jean Bodel and, for purposes of comparison, with works of two contemporary Artesian writers, Adam le Bossu and Baude Fastoul. The data indicate that Courtois d'Arras does not correspond stylistically to works known to be by Jean Bodel, and resembles more closely works not written by Bodel than those known to be canonical pieces.We then use the same methodology and some of the same data to examine three related questions. We find that the sister's scene does not resemble the rest of Courtois d'Arras and thus appears to be spurious, that Courtois d'Arras corresponds closely enough to the fabliau Boivin de Provins to suggest that these may be products of the same writer, and that the Prologue to the Jeu de saint Nicolas is very different from Bodel's typical scale and was probably not written by that author.Made available in DSpace on 2014-12-16T05:11:30Z (GMT). No. of bitstreams: 1
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Previous issue date: 1984Embargo set by: Seth Robbins for item 71203
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only167 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1984
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