A Brief History of Cryptography
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Improved Cryptanalysis of the Reduced Grøstl Compression Function, ECHO Permutation and AES Block Cipher
Improved Cryptanalysis of the Reduced Grøstl Compression Function, ECHO Permutation and AES Block Cipher Florian Mendel1, Thomas Peyrin2, Christian Rechberger1, and Martin Schl¨affer1 1 IAIK, Graz University of Technology, Austria 2 Ingenico, France [email protected],[email protected] Abstract. In this paper, we propose two new ways to mount attacks on the SHA-3 candidates Grøstl, and ECHO, and apply these attacks also to the AES. Our results improve upon and extend the rebound attack. Using the new techniques, we are able to extend the number of rounds in which available degrees of freedom can be used. As a result, we present the first attack on 7 rounds for the Grøstl-256 output transformation3 and improve the semi-free-start collision attack on 6 rounds. Further, we present an improved known-key distinguisher for 7 rounds of the AES block cipher and the internal permutation used in ECHO. Keywords: hash function, block cipher, cryptanalysis, semi-free-start collision, known-key distinguisher 1 Introduction Recently, a new wave of hash function proposals appeared, following a call for submissions to the SHA-3 contest organized by NIST [26]. In order to analyze these proposals, the toolbox which is at the cryptanalysts' disposal needs to be extended. Meet-in-the-middle and differential attacks are commonly used. A recent extension of differential cryptanalysis to hash functions is the rebound attack [22] originally applied to reduced (7.5 rounds) Whirlpool (standardized since 2000 by ISO/IEC 10118-3:2004) and a reduced version (6 rounds) of the SHA-3 candidate Grøstl-256 [14], which both have 10 rounds in total. -
Key-Dependent Approximations in Cryptanalysis. an Application of Multiple Z4 and Non-Linear Approximations
KEY-DEPENDENT APPROXIMATIONS IN CRYPTANALYSIS. AN APPLICATION OF MULTIPLE Z4 AND NON-LINEAR APPROXIMATIONS. FX Standaert, G Rouvroy, G Piret, JJ Quisquater, JD Legat Universite Catholique de Louvain, UCL Crypto Group, Place du Levant, 3, 1348 Louvain-la-Neuve, standaert,rouvroy,piret,quisquater,[email protected] Linear cryptanalysis is a powerful cryptanalytic technique that makes use of a linear approximation over some rounds of a cipher, combined with one (or two) round(s) of key guess. This key guess is usually performed by a partial decryp- tion over every possible key. In this paper, we investigate a particular class of non-linear boolean functions that allows to mount key-dependent approximations of s-boxes. Replacing the classical key guess by these key-dependent approxima- tions allows to quickly distinguish a set of keys including the correct one. By combining different relations, we can make up a system of equations whose solu- tion is the correct key. The resulting attack allows larger flexibility and improves the success rate in some contexts. We apply it to the block cipher Q. In parallel, we propose a chosen-plaintext attack against Q that reduces the required number of plaintext-ciphertext pairs from 297 to 287. 1. INTRODUCTION In its basic version, linear cryptanalysis is a known-plaintext attack that uses a linear relation between input-bits, output-bits and key-bits of an encryption algorithm that holds with a certain probability. If enough plaintext-ciphertext pairs are provided, this approximation can be used to assign probabilities to the possible keys and to locate the most probable one. -
CS 105 Review Questions #2 in Addition to These Questions
1 CS 105 Review Questions #2 In addition to these questions, remember to look over your labs, homework assignments, readings in the book and your notes. 1. Explain how writing functions inside a Python program can potentially make the program more concise (i.e. take up fewer total lines of code). 2. The following Python statement may cause a ZeroDivisionError. Rewrite the code so that the program will not automatically halt if this error occurs. c = a / b 3. Indicate whether each statement is true or false. a. In ASCII code, the values corresponding to letters in the alphabet are consecutive. b. ASCII code uses the same values for lowercase letters as it does for capital letters. c. In ASCII code, non-printing, invisible characters all have value 0 4. Properties of ASCII representation: a. Each character is stored as how much information? b. If the ASCII code for ‘A’ is 65, then the ASCII code for ‘M’ should be ______. c. Suppose that the hexadecimal ASCII code for the lowercase letter ‘a’ is 0x61. Which lowercase letter would have the hexadecimal ASCII code 0x71 ? d. If we represent the sentence “The cat slept.” in ASCII code (not including the quotation marks), how many bytes does this require? e. How does Unicode differ from ASCII? 5. Estimate the size of the following file. It contains a 500-page book, where a typical page has 2000 characters of ASCII text and one indexed-color image measuring 200x300 pixels. “Indexed color” means that each pixel of an image takes up one byte. -
Classical Encryption Techniques
CPE 542: CRYPTOGRAPHY & NETWORK SECURITY Chapter 2: Classical Encryption Techniques Dr. Lo’ai Tawalbeh Computer Engineering Department Jordan University of Science and Technology Jordan Dr. Lo’ai Tawalbeh Fall 2005 Introduction Basic Terminology • plaintext - the original message • ciphertext - the coded message • key - information used in encryption/decryption, and known only to sender/receiver • encipher (encrypt) - converting plaintext to ciphertext using key • decipher (decrypt) - recovering ciphertext from plaintext using key • cryptography - study of encryption principles/methods/designs • cryptanalysis (code breaking) - the study of principles/ methods of deciphering ciphertext Dr. Lo’ai Tawalbeh Fall 2005 1 Cryptographic Systems Cryptographic Systems are categorized according to: 1. The operation used in transferring plaintext to ciphertext: • Substitution: each element in the plaintext is mapped into another element • Transposition: the elements in the plaintext are re-arranged. 2. The number of keys used: • Symmetric (private- key) : both the sender and receiver use the same key • Asymmetric (public-key) : sender and receiver use different key 3. The way the plaintext is processed : • Block cipher : inputs are processed one block at a time, producing a corresponding output block. • Stream cipher: inputs are processed continuously, producing one element at a time (bit, Dr. Lo’ai Tawalbeh Fall 2005 Cryptographic Systems Symmetric Encryption Model Dr. Lo’ai Tawalbeh Fall 2005 2 Cryptographic Systems Requirements • two requirements for secure use of symmetric encryption: 1. a strong encryption algorithm 2. a secret key known only to sender / receiver •Y = Ek(X), where X: the plaintext, Y: the ciphertext •X = Dk(Y) • assume encryption algorithm is known •implies a secure channel to distribute key Dr. -
Computer History – the Pitfalls of Past Futures
Research Collection Working Paper Computer history – The pitfalls of past futures Author(s): Gugerli, David; Zetti, Daniela Publication Date: 2019 Permanent Link: https://doi.org/10.3929/ethz-b-000385896 Rights / License: In Copyright - Non-Commercial Use Permitted This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library TECHNIKGESCHICHTE DAVID GUGERLI DANIELA ZETTI COMPUTER HISTORY – THE PITFALLS OF PAST FUTURES PREPRINTS ZUR KULTURGESCHICHTE DER TECHNIK // 2019 #33 WWW.TG.ETHZ.CH © BEI DEN AUTOREN Gugerli, Zetti/Computer History Preprints zur Kulturgeschichte der Technik #33 Abstract The historicization of the computer in the second half of the 20th century can be understood as the effect of the inevitable changes in both its technological and narrative development. What interests us is how past futures and therefore history were stabilized. The development, operation, and implementation of machines and programs gave rise to a historicity of the field of computing. Whenever actors have been grouped into communities – for example, into industrial and academic developer communities – new orderings have been constructed historically. Such orderings depend on the ability to refer to archival and published documents and to develop new narratives based on them. Professional historians are particularly at home in these waters – and nevertheless can disappear into the whirlpool of digital prehistory. Toward the end of the 1980s, the first critical review of the literature on the history of computers thus offered several programmatic suggestions. It is one of the peculiar coincidences of history that the future should rear its head again just when the history of computers was flourishing as a result of massive methodological and conceptual input. -
COS433/Math 473: Cryptography Mark Zhandry Princeton University Spring 2017 Cryptography Is Everywhere a Long & Rich History
COS433/Math 473: Cryptography Mark Zhandry Princeton University Spring 2017 Cryptography Is Everywhere A Long & Rich History Examples: • ~50 B.C. – Caesar Cipher • 1587 – Babington Plot • WWI – Zimmermann Telegram • WWII – Enigma • 1976/77 – Public Key Cryptography • 1990’s – Widespread adoption on the Internet Increasingly Important COS 433 Practice Theory Inherent to the study of crypto • Working knowledge of fundamentals is crucial • Cannot discern security by experimentation • Proofs, reductions, probability are necessary COS 433 What you should expect to learn: • Foundations and principles of modern cryptography • Core building blocks • Applications Bonus: • Debunking some Hollywood crypto • Better understanding of crypto news COS 433 What you will not learn: • Hacking • Crypto implementations • How to design secure systems • Viruses, worms, buffer overflows, etc Administrivia Course Information Instructor: Mark Zhandry (mzhandry@p) TA: Fermi Ma (fermima1@g) Lectures: MW 1:30-2:50pm Webpage: cs.princeton.edu/~mzhandry/2017-Spring-COS433/ Office Hours: please fill out Doodle poll Piazza piaZZa.com/princeton/spring2017/cos433mat473_s2017 Main channel of communication • Course announcements • Discuss homework problems with other students • Find study groups • Ask content questions to instructors, other students Prerequisites • Ability to read and write mathematical proofs • Familiarity with algorithms, analyZing running time, proving correctness, O notation • Basic probability (random variables, expectation) Helpful: • Familiarity with NP-Completeness, reductions • Basic number theory (modular arithmetic, etc) Reading No required text Computer Science/Mathematics Chapman & Hall/CRC If you want a text to follow along with: Second CRYPTOGRAPHY AND NETWORK SECURITY Cryptography is ubiquitous and plays a key role in ensuring data secrecy and Edition integrity as well as in securing computer systems more broadly. -
Turing's Influence on Programming — Book Extract from “The Dawn of Software Engineering: from Turing to Dijkstra”
Turing's Influence on Programming | Book extract from \The Dawn of Software Engineering: from Turing to Dijkstra" Edgar G. Daylight∗ Eindhoven University of Technology, The Netherlands [email protected] Abstract Turing's involvement with computer building was popularized in the 1970s and later. Most notable are the books by Brian Randell (1973), Andrew Hodges (1983), and Martin Davis (2000). A central question is whether John von Neumann was influenced by Turing's 1936 paper when he helped build the EDVAC machine, even though he never cited Turing's work. This question remains unsettled up till this day. As remarked by Charles Petzold, one standard history barely mentions Turing, while the other, written by a logician, makes Turing a key player. Contrast these observations then with the fact that Turing's 1936 paper was cited and heavily discussed in 1959 among computer programmers. In 1966, the first Turing award was given to a programmer, not a computer builder, as were several subsequent Turing awards. An historical investigation of Turing's influence on computing, presented here, shows that Turing's 1936 notion of universality became increasingly relevant among programmers during the 1950s. The central thesis of this paper states that Turing's in- fluence was felt more in programming after his death than in computer building during the 1940s. 1 Introduction Many people today are led to believe that Turing is the father of the computer, the father of our digital society, as also the following praise for Martin Davis's bestseller The Universal Computer: The Road from Leibniz to Turing1 suggests: At last, a book about the origin of the computer that goes to the heart of the story: the human struggle for logic and truth. -
THE-POLISH-TRACE-Ebook.Pdf
8 THE POLISH TRACE COMPOSED FROM COMMONLY AVAILABLE SOURCES BY LECH POLKOWSKI FOR IJCRS2017 FOREWORD It is a desire of many participants of conferences to learn as much as possible about the history and culture of he visited country and place and organizers try to satisfy this desire by providing excursions into attractive places and sites. IJCRS2017 also tries to take participants to historic sites of Warmia and Mazury and to show elements of local culture. As an innovation, we propose a booklet showing some achievements of Polish scientists and cryptographers, no doubt many of them are known universally, but some probably not. What bounds all personages described here is that they all suffered due to world wars, th efirst and the second. These wars ruined their homes, made them refugees and exiles, destroyed their archives and libraries, they lost many colleagues, friends and students but were lucky enough to save lives and in some cases to begin the career overseas. We begin with the person of Jan Czochralski, world famous metallurgist, discoverer of the technique of producing metal monocrystals `the Czochralski methode’ and inventor of duraluminum and the `bahnalloy’ who started his career and obtained its heights in Germany, later returned to Poland, became a professor at the Warsaw Polytechnical, played an important role in cultural life of Warsaw, lived in Warsaw through the second world war and the Warsaw Uprising of August-September 1944 and after the war was accused of cooperating ith occupying German forces and though judged innocent was literally erased from the public life and any information about him obliterated. -
Polska Myśl Techniczna W Ii Wojnie Światowej
CENTRALNA BIBLIOTEKA WOJSKOWA IM. MARSZAŁKA JÓZEFA PIŁSUDSKIEGO POLSKA MYŚL TECHNICZNA W II WOJNIE ŚWIATOWEJ W 70. ROCZNICĘ ZAKOŃCZENIA DZIAŁAŃ WOJENNYCH W EUROPIE MATERIAŁY POKONFERENCYJNE poD REDAkcJą NAUkoWą DR. JANA TARCZYńSkiEGO WARSZAWA 2015 Konferencja naukowa Polska myśl techniczna w II wojnie światowej. W 70. rocznicę zakończenia działań wojennych w Europie Komitet naukowy: inż. Krzysztof Barbarski – Prezes Instytutu Polskiego i Muzeum im. gen. Sikorskiego w Londynie dr inż. Leszek Bogdan – Dyrektor Wojskowego Instytutu Techniki Inżynieryjnej im. profesora Józefa Kosackiego mgr inż. Piotr Dudek – Prezes Stowarzyszenia Techników Polskich w Wielkiej Brytanii gen. dyw. prof. dr hab. inż. Zygmunt Mierczyk – Rektor-Komendant Wojskowej Akademii Technicznej im. Jarosława Dąbrowskiego płk mgr inż. Marek Malawski – Szef Inspektoratu Implementacji Innowacyjnych Technologii Obronnych Ministerstwa Obrony Narodowej mgr inż. Ewa Mańkiewicz-Cudny – Prezes Federacji Stowarzyszeń Naukowo-Technicznych – Naczelnej Organizacji Technicznej prof. dr hab. Bolesław Orłowski – Honorowy Członek – założyciel Polskiego Towarzystwa Historii Techniki – Instytut Historii Nauki Polskiej Akademii Nauk kmdr prof. dr hab. Tomasz Szubrycht – Rektor-Komendant Akademii Marynarki Wojennej im. Bohaterów Westerplatte dr Jan Tarczyński – Dyrektor Centralnej Biblioteki Wojskowej im. Marszałka Józefa Piłsudskiego prof. dr hab. Leszek Zasztowt – Dyrektor Instytutu Historii Nauki Polskiej Akademii Nauk dr Czesław Andrzej Żak – Dyrektor Centralnego Archiwum Wojskowego im. -
9 Purple 18/2
THE CONCORD REVIEW 223 A VERY PURPLE-XING CODE Michael Cohen Groups cannot work together without communication between them. In wartime, it is critical that correspondence between the groups, or nations in the case of World War II, be concealed from the eyes of the enemy. This necessity leads nations to develop codes to hide their messages’ meanings from unwanted recipients. Among the many codes used in World War II, none has achieved a higher level of fame than Japan’s Purple code, or rather the code that Japan’s Purple machine produced. The breaking of this code helped the Allied forces to defeat their enemies in World War II in the Pacific by providing them with critical information. The code was more intricate than any other coding system invented before modern computers. Using codebreaking strategy from previous war codes, the U.S. was able to crack the Purple code. Unfortunately, the U.S. could not use its newfound knowl- edge to prevent the attack at Pearl Harbor. It took a Herculean feat of American intellect to break Purple. It was dramatically intro- duced to Congress in the Congressional hearing into the Pearl Harbor disaster.1 In the ensuing years, it was discovered that the deciphering of the Purple Code affected the course of the Pacific war in more ways than one. For instance, it turned out that before the Americans had dropped nuclear bombs on Japan, Purple Michael Cohen is a Senior at the Commonwealth School in Boston, Massachusetts, where he wrote this paper for Tom Harsanyi’s United States History course in the 2006/2007 academic year. -
Passwords, Hashes, and Cracks, Oh My! How Mac OS X Implements Password Authentication Dave Dribin “Why Should I Care?”
Passwords, Hashes, and Cracks, Oh My! How Mac OS X Implements Password Authentication Dave Dribin “Why Should I Care?” • Application Developer • System Administrator • End User Authentication • Authentication is the process of attempting to verify a user’s identity • Passwords authenticate using a “shared secret” History • Mac OS X based on NeXTSTEP • NeXTSTEP Unix on top of Mach • Unix developed by AT&T Bell Labs on DEC PDP-11 • Unix based on mainframe time-sharing systems UNIX Time-Sharing System Version 1 • Released in 1971 • First release of Unix as we know it • Plaintext passwords Plaintext Problems “Perhaps the most memorable [example] occurred in the early 60’s when a system administrator on the CTSS system at MIT was editing the password file and another system administrator was editing the daily message that is printed on everyone’s terminal on login. Due to a software design error, the temporary editor files of the two users were interchanged and thus, for a time, the password file was printed on every terminal when it was logged in.” -- Robert Morris and Ken Thompson, April 3,1978 Unix Versions 3, 4, 5, 6 • Released 1973 through 1975 • Encrypted Password • Password file is readable by all NAME passwd -- password file DESCRIPTION passwd contains for each user the following in- formation: name (login name, contains no upper case) encrypted password numerical user ID GCOS job number and box number initial working directory program to use as Shell This is an ASCII file. Each field within each user's entry is separated from the next by a colon. -
An Archeology of Cryptography: Rewriting Plaintext, Encryption, and Ciphertext
An Archeology of Cryptography: Rewriting Plaintext, Encryption, and Ciphertext By Isaac Quinn DuPont A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Faculty of Information University of Toronto © Copyright by Isaac Quinn DuPont 2017 ii An Archeology of Cryptography: Rewriting Plaintext, Encryption, and Ciphertext Isaac Quinn DuPont Doctor of Philosophy Faculty of Information University of Toronto 2017 Abstract Tis dissertation is an archeological study of cryptography. It questions the validity of thinking about cryptography in familiar, instrumentalist terms, and instead reveals the ways that cryptography can been understood as writing, media, and computation. In this dissertation, I ofer a critique of the prevailing views of cryptography by tracing a number of long overlooked themes in its history, including the development of artifcial languages, machine translation, media, code, notation, silence, and order. Using an archeological method, I detail historical conditions of possibility and the technical a priori of cryptography. Te conditions of possibility are explored in three parts, where I rhetorically rewrite the conventional terms of art, namely, plaintext, encryption, and ciphertext. I argue that plaintext has historically been understood as kind of inscription or form of writing, and has been associated with the development of artifcial languages, and used to analyze and investigate the natural world. I argue that the technical a priori of plaintext, encryption, and ciphertext is constitutive of the syntactic iii and semantic properties detailed in Nelson Goodman’s theory of notation, as described in his Languages of Art. I argue that encryption (and its reverse, decryption) are deterministic modes of transcription, which have historically been thought of as the medium between plaintext and ciphertext.