DOCSLIB.ORG

The Cryptanalysis of a Three Rotor Machine Using a Genetic Algorithm

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Cryptanalysis of a Three Rotor Machine Using a Genetic Algorithm The Cryptanalysis of a Three Rotor Machine Using a Genetic Algorithm A J Bagnall G P McKeown and V J RaywardSmith Scho ol of Information Systems University of East Anglia Norwich NR TJ England Abstract Weshow that a genetic algorithm can b e used to suc cessfully search the very large discrete keyspace of a rotor machine of magnitude up to using a sim This pap er describ es a metho d of decipher ple statistical measure of suitability The metho d in ing messages encrypted with rotor machines volves nding the last rotor of a three rotor machine utilising a Genetic Algorithm to search the using a GA and then solving the resulting two rotor keyspace A tness measure based on the phi machine using the iterative technique describ ed in test for non randomness of text is describ ed The plaintext is assumed to be n indep endent reali and the results show that an unknown three sations of a random variable dened on alphab et Z q rotor machine can generally b e cryptanalysed with probability distribution derived from observation with ab out letters of ciphertext The of the single letter frequencies of English The distri results are compared to those given using a bution we use is that given in The statistical mea previously published technique and found to sure of tness is based on the fact that a two rotor ma b e sup erior chine with o dometerlike rotation is p erio dic with p e rio d q If we map the ciphertext through the correct last rotor with a known rotation pattern and split this new ciphertext into q ciphertext strings these INTRODUCTION strings will exhibit the characteristics of monoalpha b etically enciphered plaintext Based on the statis A cryptographic system eects an enciphering trans tic for testing the nonrandomness of text see the formation from plaintext x to ciphertext y bothof tness for any prop osed last rotor is the probabil which are vectors of n letters from a nite set of sym ity of having observed an average value at least as b ols an alphab et of size q whichwe call Z A key k q large as the value actually observed given and that for a cryptographic system is a parameter dened on a the text mapp ed through results from q monoal key space K with the prop erty that knowledge of the phab etic substitutions of the plaintext value of k will enable the recovery of plaintext from ciphertext Cryptanalysis is the pro cess of attempting to recover encrypted plaintext without knowledge of the key In this pap er we consider cryptanalysis with ROTOR MACHINES ciphertext only as opp osed to with known or chosen plaintext and ciphertext It is the former situation Rotor machines formed the basis for most military and which presents the hardest problem for the attacker commercial cryptography until the late s The Genetic Algorithms GAs have previously b een used German Enigma the Heb ern machine and the Con in cryptanalysis for solving simple substitution sys verter M all describ ed in are variations on the tems transp osition ciphers and knapsackbased basic machine weuse systems The cryptographic systems solved are all A rotor machine is a cryptographic device consist fairly straightforward and readily solvable by other ing of N rotors A rotor is a disk with a no de on metho ds For example gives various metho ds for each side for each letter in the appropriate alphab et solving knapsack problems larger than those solved size q and electrical contacts b etween the no des ef in fecting a substitution After eachsuch substitution th enciphering substitution for the i letter of plaintext en by A A is giv B B C C r i r i r i m m m S R i C C C m D D m r i r i r i E E m C C C F F verse G G and the deciphering substitution is the in H H r i r i r i r i S R i C C C C r i r i m m C C m t functions is usually assumed A The set of displacemen be known A common set of displacement func A to B B are those that follow an o dometerlike rotation C C tions has D D pattern suc E s r ibiq c sm i E s F F m rotor system with o dometerlike displacement G G An R is a polyalphabetic substitution system H H functions dened by the sequence of substitutions Figure A three rotor machine for an eight letter SR i j i alphab et b efore and after the rst rotor has rotated m one place with period P which divides q A rotor machine with a set of displacement functions which are not m o dometerlike can at most pro duce q dierent sub the contacts rotate in accordance with a rotation pat stitutions A fuller mathematical description of rotor tern while the no des remain in the same p osition or machines is given in vice versa Rotating a rotor a places yields another usually dierent substitution The key for a rotor machine must dene a a S a C C the numb er of rotors m S a is the comp osition of with the Caesar sub the initial rotor substitutions a a a stitutions C and C A Caesar substitution C is simply a shift of a places the displacement functions R C i i a a iq a We assume the numb er of rotors is known and that the setofdisplacement functions follow the o dometerlike Rotor machines are built by concatenating rotors Let pattern describ ed ab ove So the keyspace K is the set of all Ntuples of p ossible substitutions and a key f g m k is an element of a subset of K The cryptanalysis problem is to nd an estimate of k k given a string b e a set of substitutions representing a bank of m ro of ciphertext tors for encipherment of the rst letter and R fr r r g m CRYPTANALYSIS OF A THREE b e a set of displacement functions ROTOR MACHINE r Z Z s q q Our metho d of attack is to nd the last rotor of a r s three rotor machine using a Genetic Algorithm GA r i r i s mi s s and then to solve the resulting two rotor machine us th where r i is the rotational displacement of the s ing the iterativetechnique describ ed in s th rotor for the encipherment of the i elementofx The Each string results from monoalphab etic encipher GENETIC ALGORITHMS ment Mapping the ciphertext through the correct We implemented the problem on the XGAmeter last rotor of a rotor machine with periodic rotation toolkit develop ed at the UEA which enables the will pro duce a new ciphertext string with the prop erty m easy use of GAs on a variety of problems The deci that the q text strings will exhibit the nonrandom sions in implementing a GA for a particular problem prop erties of the plaintext distribution We can then are concerned with representation tness evaluation reduce the search space to the p ossible wirings of the and the select create and merge metho ds The stop last rotor and consider a tness measure for this non ping condition we use is to halt the GA if there had randomness b een no change in the b est solution so far in gen erations Phi test Representation Consider v indep endent observations of random vari able X with sample space of size q and with range The most obvious representation of a rotor is an array Z Supp ose that the observed frequencies of eachof q of m integers representing the wiring from each p osi the elements in is given by f f f If we q tion The subset of the keyspace containing correct dene the statistic as keys for a three rotor machine with known rotation q functions has magnitude q That is to say there are X f f multiple solutions to a rotor machine with more than i i i one rotor If we dene the set of rotors then f g E s v v where and the variance is b b q C v s s v s s s v s s s and b b C C b q where q q then if X X b s P X i and s P X i C i i r r r r r r C C C C C S R C See for further description of the statistic and b b r r b r pro of of the ab ove results If random variable X has a C C C C C C r b r r probability distribution given by our single letter fre C C C C quency distribution then r r r r r r C C C C C C E v v S R and This means that we can arbitrarily x a wiring in the we set last rotors For any prop osed solution v v v and For a p olyalphab etic substitution with p erio d P and ciphertext y of length n if we assume n is divisible Fitness by P for simplicity then the P strings of text y j of length nP can b e considered as P observations of The basis for our tness evaluation is that plaintext en random variable dened on the sample space of all ciphered by a monoalphab etic substitution will still ex nP p ossible letter combinations Then hibit characteristics of the original distribution Ape P rio dic p olyalphab etic substitution system with p erio d P i i P can b e reduced to a series of monoalphab etic sub P stitution systems by splitting the ciphertext y into P text strings y where and j y iy i P j for jP i nP j P By the Central Limit Theorem the limiting form Mutation of the distribution of In order to maintain diversityandavoid lo calised hill Z climbing it is desirable that when an ospring is cre ated there is a chance that it may mutate We used the following twomutation op erators is the standard normal distribution m So if welet t q the tness of a prop osed last randomly swap two rotor wirings ie eect a ran rotor is calculated as follows dom transp osition on an ospring shift a randomly selected substring of rotor let y b e the transformed ciphertext found by sub wirings to random p osition jecting ciphertext y to the sequence of substitu tions S r i for in offspring : 5 1 3 2 6 4 7 8 9 Let y b e substrings of y such that j random
Load more

Recommended publications
  • The Mathemathics of Secrets.Pdf
    THE MATHEMATICS OF SECRETS THE MATHEMATICS OF SECRETS CRYPTOGRAPHY FROM CAESAR CIPHERS TO DIGITAL ENCRYPTION JOSHUA HOLDEN PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD Copyright c 2017 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 1TR press.princeton.edu Jacket image courtesy of Shutterstock; design by Lorraine Betz Doneker All Rights Reserved Library of Congress Cataloging-in-Publication Data Names: Holden, Joshua, 1970– author. Title: The mathematics of secrets : cryptography from Caesar ciphers to digital encryption / Joshua Holden. Description: Princeton : Princeton University Press, [2017] | Includes bibliographical references and index. Identifiers: LCCN 2016014840 | ISBN 9780691141756 (hardcover : alk. paper) Subjects: LCSH: Cryptography—Mathematics. | Ciphers. | Computer security. Classification: LCC Z103 .H664 2017 | DDC 005.8/2—dc23 LC record available at https://lccn.loc.gov/2016014840 British Library Cataloging-in-Publication Data is available This book has been composed in Linux Libertine Printed on acid-free paper. ∞ Printed in the United States of America 13579108642 To Lana and Richard for their love and support CONTENTS Preface xi Acknowledgments xiii Introduction to Ciphers and Substitution 1 1.1 Alice and Bob and Carl and Julius: Terminology and Caesar Cipher 1 1.2 The Key to the Matter: Generalizing the Caesar Cipher 4 1.3 Multiplicative Ciphers 6
    [Show full text]
  • The the Enigma Enigma Machinemachine
    TheThe EnigmaEnigma MachineMachine History of Computing December 6, 2006 Mike Koss Invention of Enigma ! Invented by Arthur Scherbius, 1918 ! Adopted by German Navy, 1926 ! Modified military version, 1930 ! Two Additional rotors added, 1938 How Enigma Works Scrambling Letters ! Each letter on the keyboard is connected to a lamp letter that depends on the wiring and position of the rotors in the machine. ! Right rotor turns before each letter. How to Use an Enigma ! Daily Setup – Secret settings distributed in code books. ! Encoding/Decoding a Message Setup: Select (3) Rotors ! We’ll use I-II-III Setup: Rotor Ring Settings ! We’ll use A-A-A (or 1-1-1). Rotor Construction Setup: Plugboard Settings ! We won’t use any for our example (6 to 10 plugs were typical). Setup: Initial Rotor Position ! We’ll use “M-I-T” (or 13-9-20). Encoding: Pick a “Message Key” ! Select a 3-letter key (or indicator) “at random” (left to the operator) for this message only. ! Say, I choose “M-C-K” (or 13-3-11 if wheels are printed with numbers rather than letters). Encoding: Transmit the Indicator ! Germans would transmit the indicator by encoding it using the initial (daily) rotor position…and they sent it TWICE to make sure it was received properly. ! E.g., I would begin my message with “MCK MCK”. ! Encoded with the daily setting, this becomes: “NWD SHE”. Encoding: Reset Rotors ! Now set our rotors do our chosen message key “M-C-K” (13-3-11). ! Type body of message: “ENIGMA REVEALED” encodes to “QMJIDO MZWZJFJR”.
    [Show full text]
  • Practical Aspects of Modern Cryptography
    University of Washington CSEP 590TU – Practical Aspects of Modern Cryptography Instructors: Josh Benaloh, Brian LaMacchia, John Manferdelli Tuesdays: 6:30-9:30, Allen Center 305 Webpage: http://www.cs.washington.edu/education/courses/csep590/06wi/ Recommended texts: Stinson, Cryptography, Theory and Practice. 2nd Edition, CRC Press, 2002. Menezes, vanOrtshot, Vanstone. Handbook of Applied Cryptography. Ferguson and Schneier, Practical Cryptography. JLM 20060107 22:16 1 New Lecture Schedule Date Topic Lecturer 1 1/3 Practical Aspects of Cryptography Josh 2 1/10 Symmetric Key Ciphers and Hashes John 3 1/17 Public Key Ciphers Josh 4 1/24 Cryptographic Protocols I Brian 5 1/31 Cryptographic Protocols II Brian 6 2/7 Security of Block Ciphers John 7 2/14 AES and Cryptographic Hashes John 8 2/21 Trust, PKI, Key Management [Last HW Brian Assignment) 9 3/1 Random Numbers/Elliptic Curve Crypto Josh 10 3/8 Three topics: Elections, ITAR/Politics, Side All Channels/Timing Attacks, DRM, BigNum Implementation JLM 20060107 22:16 2 Symmetric Key Cryptography and Cryptographic Hashes - I John Manferdelli [email protected] [email protected] Portions © 2004-2005, John Manferdelli. This material is provided without warranty of any kind including, without limitation, warranty of non-infringement or suitability for any purpose. This material is not guaranteed to be error free and is intended for instructional use only. JLM 20060107 22:16 3 Communications Engineers Coat of Arms The Source Sender: Alice Noisy insecure channel Plaintext Compress Encrypt Encode (P) (to save space) (for confidentiality) (to correct errors) The Sink Receiver:Bob Noisy insecure channel Decode Decrypt Decompress Plaintext (for confidentiality) (to correct errors) (to save space) (P) JLM 20060107 22:16 4 Symmetric Encryption Plaintext (P) Encrypt Ciphertext (C) E (P) Key (k) k Ciphertext (C) Decrypt Plaintext (P) D (P) Key (k) k • Symmetric Key cryptographic algorithms use a secret known to the authorized parties called a “key”.
    [Show full text]
  • ISA 562 Information Security Theory & Practice
    ISA 562 Information Security Theory & Practice Introduction to Cryptography Agenda • Basics & Definitions • Classical Cryptography • Symmetric (Secret Key) Cryptography • DES (Data Encryption Standard) • Multiple Encryptions • Modes of Block Cipher Operations • Math Essential • Asymmetric (Public Key) Cryptography 2 1 Basics & Definitions Security Concepts (I) • Confidentiality – Prevent information from being exposed to unintended party – Ex: An employee should not come to know the salary of his manager • Integrity – Assure that the information has not been tempered – Ex: An employee should not be able to modify the employee's own salary • Identity – Assure that the party of concern is authentic - it is what it claims to be – Ex: An employee should be able to uniquely identify and authenticate himself/herself 4 2 Security Concepts (II) • Availability – Assure that unused service or resource is available to legitimate users – Ex: Paychecks should be printed on time as stipulated by law • Anonymity – Assure that the identity of some party is remain anonymous – Ex: The manager should not know who had a critical review of him • Non-Repudiation – Assure that authenticated party has indeed done something that cannot be denied – Ex: Once the employee has cashed his paycheck, he can’t deny it. 5 Cryptography • Crypt = secret • Graph = writing • Cryptography is the science / art of transforming meaningful information into unintelligible text Becoming a science that relies on mathematics (number theory, algebra) • Cryptanalysis is the science / art of breaking cryptographic codes • Cryptology is the science / art / study of both cryptography and cryptanalysis 6 3 Applications of Cryptography • Assuring document integrity • Assuring document confidentiality • Authenticating parties • Document signature • Non-repudiation • Secure transactions • Exchanging keys • Sharing Secrets • Digital cash • Preserving anonymity • Copyright protection • More .
    [Show full text]
  • Communication Intelligence and Security, William F Friedman
    UNCLASSIFIED DATE: 26 April 1960 NAME: Friedman, William F. PLACE: Breckinridge Hall, Marine Corp School TITLE: Communications Intelligence and Security Presentation Given to Staff and Students; Introduction by probably General MILLER (NFI) Miller: ((TR NOTE: Introductory remarks are probably made by General Miller (NFI).)) Gentleman, I…as we’ve grown up, there have been many times, I suppose, when we’ve been inquisitive about means of communication, means of finding out what’s going on. Some of us who grew up out in the country used to tap in on a country telephone line and we could find out what was going on that way—at least in the neighborhood. And then, of course, there were always a few that you’d read about in the newspaper who would carry this a little bit further and read some of your neighbor’s mail by getting at it at the right time, and reading it and putting it back. Of course, a good many of those people ended up at a place called Fort Leavenworth. This problem of security of information is with us in the military on a [sic] hour-to-hour basis because it’s our bread and butter. It’s what we focus on in the development of our combat plans in an attempt to project these plans onto an enemy and defeat him. And so, we use a good many devices. We spend a tremendous amount of effort and money in attempting to keep our secrets in fact secret—at least at the echelon where we feel this is necessary.
    [Show full text]
  • A Complete Bibliography of Publications in Cryptologia
    A Complete Bibliography of Publications in Cryptologia Nelson H. F. Beebe University of Utah Department of Mathematics, 110 LCB 155 S 1400 E RM 233 Salt Lake City, UT 84112-0090 USA Tel: +1 801 581 5254 FAX: +1 801 581 4148 E-mail: [email protected], [email protected], [email protected] (Internet) WWW URL: http://www.math.utah.edu/~beebe/ 04 September 2021 Version 3.64 Title word cross-reference 10016-8810 [?, ?]. 1221 [?]. 125 [?]. 15.00/$23.60.0 [?]. 15th [?, ?]. 16th [?]. 17-18 [?]. 18 [?]. 180-4 [?]. 1812 [?]. 18th (t; m)[?]. (t; n)[?, ?]. $10.00 [?]. $12.00 [?, ?, ?, ?, ?]. 18th-Century [?]. 1930s [?]. [?]. 128 [?]. $139.99 [?]. $15.00 [?]. $16.95 1939 [?]. 1940 [?, ?]. 1940s [?]. 1941 [?]. [?]. $16.96 [?]. $18.95 [?]. $24.00 [?]. 1942 [?]. 1943 [?]. 1945 [?, ?, ?, ?, ?]. $24.00/$34 [?]. $24.95 [?, ?]. $26.95 [?]. 1946 [?, ?]. 1950s [?]. 1970s [?]. 1980s [?]. $29.95 [?]. $30.95 [?]. $39 [?]. $43.39 [?]. 1989 [?]. 19th [?, ?]. $45.00 [?]. $5.95 [?]. $54.00 [?]. $54.95 [?]. $54.99 [?]. $6.50 [?]. $6.95 [?]. $69.00 2 [?, ?]. 200/220 [?]. 2000 [?]. 2004 [?, ?]. [?]. $69.95 [?]. $75.00 [?]. $89.95 [?]. th 2008 [?]. 2009 [?]. 2011 [?]. 2013 [?, ?]. [?]. A [?]. A3 [?, ?]. χ [?]. H [?]. k [?, ?]. M 2014 [?]. 2017 [?]. 2019 [?]. 20755-6886 [?, ?]. M 3 [?]. n [?, ?, ?]. [?]. 209 [?, ?, ?, ?, ?, ?]. 20th [?]. 21 [?]. 22 [?]. 220 [?]. 24-Hour [?, ?, ?]. 25 [?, ?]. -Bit [?]. -out-of- [?, ?]. -tests [?]. 25.00/$39.30 [?]. 25.00/839.30 [?]. 25A1 [?]. 25B [?]. 26 [?, ?]. 28147 [?]. 28147-89 000 [?]. 01Q [?, ?]. [?]. 285 [?]. 294 [?]. 2in [?, ?]. 2nd [?, ?, ?, ?]. 1 [?, ?, ?, ?]. 1-4398-1763-4 [?]. 1/2in [?, ?]. 10 [?]. 100 [?]. 10011-4211 [?]. 3 [?, ?, ?, ?]. 3/4in [?, ?]. 30 [?]. 310 1 2 [?, ?, ?, ?, ?, ?, ?]. 312 [?]. 325 [?]. 3336 [?, ?, ?, ?, ?, ?]. affine [?]. [?]. 35 [?]. 36 [?]. 3rd [?]. Afluisterstation [?, ?]. After [?]. Aftermath [?]. Again [?, ?]. Against 4 [?]. 40 [?]. 44 [?]. 45 [?]. 45th [?]. 47 [?]. [?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?]. Age 4in [?, ?]. [?, ?]. Agencies [?]. Agency [?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?].
    [Show full text]
  • Cryptography
    CS 419: Computer Security Week 6: Cryptography © 2020 Paul Krzyzanowski. No part of this Paul Krzyzanowski content, may be reproduced or reposted in whole or in part in any manner without the permission of the copyright owner. cryptography κρυπός γραφία hidden writing A secret manner of writing, … Generally, the art of writing or solving ciphers. — Oxford English Dictionary October 16, 2020 CS 419 © 2020 Paul Krzyzanowski 2 cryptanalysis κρυπός ἀνάλυσις hidden action of loosing, solution of a problem, undo The analysis and decryption of encrypted text or information without prior knowledge of the keys. — Oxford English Dictionary October 16, 2020 CS 419 © 2020 Paul Krzyzanowski 3 cryptology κρυπός λογια hidden speaking (knowledge) 1967 D. Kahn, Codebreakers p. xvi, Cryptology is the science that embraces cryptography and cryptanalysis, but the term ‘cryptology’ sometimes loosely designates the entire dual field of both rendering signals secure and extracting information from them. — Oxford English Dictionary October 16, 2020 CS 419 © 2020 Paul Krzyzanowski 4 Cryptography ¹ Security Cryptography may be a component of a secure system Just adding cryptography may not make a system secure October 16, 2020 CS 419 © 2020 Paul Krzyzanowski 5 Cryptography: what is it good for? • Confidentiality – Others cannot read contents of the message • Authentication – Determine origin of message • Integrity – Verify that message has not been modified • Nonrepudiation – Sender should not be able to falsely deny that a message was sent October 16, 2020 CS
    [Show full text]
  • Cryptography
    Cryptography © André Zúquete / João Paulo Barraca Security 1 Cryptography: terminology (1/2) w Cryptography ® Art or science of hidden writing • from Gr. kryptós , hidden + graph , r. of graphein , to write ® It was initially used to maintain the confidentiality of information ® Steganography • from Gr. steganós , hidden + graph , r. of graphein , to write w Cryptanalysis ® Art or science of breaking cryptographic systems or encrypted information w Cryptology ® Cryptography + cryptanalysis © André Zúquete / João Paulo Barraca Security 2 1 Cryptography: terminology (2/2) w Cipher ® Specific cryptographic technique w Cipher operation Encryption : plaintext ( or cleartext ) ciphertext ( or cryptogram ) Decryption : ciphertext plaintext Algorithm : way of transforming data Key : algorithm parameter encrypt() plaintext ciphertext decrypt() © André Zúquete / João Paulo Barraca Security 3 Use cases (symmetric cryptography) w Self-protection with key K ® Alice encrypts plaintext P with key K A: C = {P} K ® Alice decrypts cryptogram C with key K A: P’ = {C} K ® P’ should be equal to P (requires checking) w Secure communication with key K ® Alice encrypts plaintext P with key K A: C = {P} K ® Bob decrypts C with key K B: P’ = {C} K ® P’ should be equal to P (requires checking) © André Zúquete / João Paulo Barraca Security 4 2 Cryptanalysis: goals w Discover original plaintext ® Which originated a given ciphertext w Discover a cipher key ® Allows the decryption of ciphertexts created with the same key w Discover the cipher algorithm ® Or an equivalent
    [Show full text]
  • Assessing the Viability of the Rotor Cipher in the Modern World
    Assessing the Viability of the Rotor Cipher in the Modern World by Jordan Zink Gahanna Lincoln High School 140 S Hamilton Road Gahanna, Ohio 43230 [email protected] (614) 307-3669 Prepared for GLHS Science Academy Symposium February 5, 2010 2 ASSESSING THE VIABILITY OF THE ROTOR CIPHER IN THE MODERN WORLD Jordan Zink Gahanna Lincoln High School, 140 S Hamilton Road, Gahanna, Ohio 43230 The purpose of this project is to determine the viability of the rotor cipher in the modern world of computer cryptography. This project consists of two phases: modifying the cipher to increase its security and running a simulation to assess the effectiveness of a brute force attack. While many modifications were made, one modification involved shortening the plaintext before encryption by removing unnecessary letters and replacing words with symbols. An experiment was run to determine the level of shortening that would not distort meaning. 20 subjects participated and it was found that a conservative level of shortening did not significantly distort meaning, while a liberal level of shortening did distortion meaning slightly. It was also found that there was no significant difference between youth and adult subjects, or between subjects familiar and unfamiliar with texting and online lingo. To simulate a brute force attack, a computer program was written in Visual Basic. Initial testing found household computers could not break a message encrypted with 3 or more rotors. A regression equation was found to predict the key search speed based on plaintext length (R2 = 0.9988). Also, the equation t = 2562n/s was created to showed the relation of time to run a brute force attack to the number of rotors and the key search speed.
    [Show full text]
  • Cryptography
    Cristina Nita-Rotaru CS355: Cryptography Lecture 4: Enigma. Towards cryptographic engines } How to move from pencil and paper to more automatic ways of encrypting and decrypting? } How to design more secure ciphers } Alberti’s Disk } Jefferson’s Wheel } Enigma 2 Cristina Nita-Rotaru Alberti disk - 1467 } Outer is fixed } Insider is mobile 3 Cristina Nita-Rotaru Alberti disk } The numbers on outer disks are used to code pre- determined passphrases } Encode: on inner disk there is a mark which could be lined up with a letter on the outer disc as a key } Decode: } Need to use a disk with a matching alphabet on the inner ring } Need to know the correct letter to match the mark to rotate the inner disk 4 Cristina Nita-Rotaru Jefferson wheel cipher - 1790 } 15 x 4 cm } slice about 5mm across } 26 sections } one letter is assigned randomly to each section. 5 Cristina Nita-Rotaru Jefferson cipher } Encode: a fragment of the message appears along one side of the cylinder, the cylinder is then turned and another line is copied out at random } Decode: } Use the cylinder to enter the ciphertext, and then turn the cylinder examining each row until the plaintext is seen. } Same cylinder must be used for both encryption and decryption 6 Cristina Nita-Rotaru Rotor machines } Vigenere can be broken once somebody finds the key length } How to have a longer key? } Idea: } Multiple rounds of substitution, encryption consists of mapping a letter many times } Mechanical/electrical wiring to automate the encryption/decryption process } A machine consists of
    [Show full text]
  • Enigma Cipher Machine Simulator 7.0.5
    ENIGMA CIPHER MACHINE SIMULATOR 7.0.5 About the Enigma Simulator The German Enigma machine is the most famous example of the battle between codemakers and codebreakers. Never before has the fate of so many lives been so influenced by one cryptographic machine, as the Enigma did in the Second World War. The story of Enigma combines technology, military history, espionage, codebreaking and intelligence into a real thriller. This software is an exact simulation of the 3-rotor Heer (Army) and Luftwaffe (Airforce) Wehrmacht Enigma I, the Kriegsmarine (wartime Navy) Enigma M3 and the famous 4-rotor Enigma M4, as they were used during World War II from 1939 until 1945. The internal wiring of all rotors is identical to those used by the Heer, Luftwaffe and Kriegsmarine. This simulator is therefore fully compatible with the real Enigma machine and you can decipher original messages and encipher your own messages. You can use the Enigma simulator in exactly the same way as a German signal trooper would have done during WW2. The hands-on approach and realistic graphics ensure an authentic feeling. You can open the machine, change the internal settings, select rotors from the spare box, preset their ring settings, insert them into the machine and set the plugboard. The sounds are recorded from an actual Enigma machine. This manual explains how to use the Enigma simulator, the message procedures as used by the German Armed Forces, including some authentic message examples, a complete technical description and a brief history of the Enigma. More information on the Enigma machine is found at the Cipher Machines & Cryptology website: http://users.telenet.be/d.rijmenants This manual is copyrighted.
    [Show full text]
  • Cryptanalysis of the SIGABA
    UNIVERSITY OF CALIFORNIA Santa Barbara Cryptanalysis of the SIGABA A Thesis submitted in partial satisfaction of the requirements for the degree Master of Science in Computer Science by Michael Lee Committee in charge: Professor Alan G. Konheim, Chair Professor Richard A. Kemmerer Professor Giovanni Vigna June 2003 The Thesis of Michael Lee is approved. Richard A. Kemmerer Giovanni Vigna Alan G. Konheim, Committee Chair June 2003 Cryptanalysis of the SIGABA Copyright c 2003 by Michael Lee iii ABSTRACT Cryptanalysis of the SIGABA by Michael Lee The SIGABA is a rotor-based cryptosystem developed by the United States for use during World War II. Its history has been shrouded in secrecy, with the result that few people know of its significance in securing American communica- tions during and after World War II. SIGABA’s operational details were finally declassified in 1996, and the patent for its design was granted in 2001, more than 50 years after it was filed. In this thesis I present a generic model of rotor-based cryptosystems that represents a machine at least as difficult to break as the SIGABA. I present tech- niques that can be used for full plaintext recovery on a cryptosystem using one to three rotors, and I show how these techniques can be extended to systems using more rotors. These attacks compromise not only the generic model, but also the SIGABA and related cryptosystems. Keywords: rotor machines, cryptanalysis, cribbing, SIGABA, ECM Mark II, CSP-889, M-134-C. iv Contents List of Figures vii List of Tables viii 1 Introduction 1 2 Rotors 3 2.1 Rotor Construction .
    [Show full text]