Cryptography and Data Security
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Chapter 3 – Block Ciphers and the Data Encryption Standard
Chapter 3 –Block Ciphers and the Data Cryptography and Network Encryption Standard Security All the afternoon Mungo had been working on Stern's Chapter 3 code, principally with the aid of the latest messages which he had copied down at the Nevin Square drop. Stern was very confident. He must be well aware London Central knew about that drop. It was obvious Fifth Edition that they didn't care how often Mungo read their messages, so confident were they in the by William Stallings impenetrability of the code. —Talking to Strange Men, Ruth Rendell Lecture slides by Lawrie Brown Modern Block Ciphers Block vs Stream Ciphers now look at modern block ciphers • block ciphers process messages in blocks, each one of the most widely used types of of which is then en/decrypted cryptographic algorithms • like a substitution on very big characters provide secrecy /hii/authentication services – 64‐bits or more focus on DES (Data Encryption Standard) • stream ciphers process messages a bit or byte at a time when en/decrypting to illustrate block cipher design principles • many current ciphers are block ciphers – better analysed – broader range of applications Block vs Stream Ciphers Block Cipher Principles • most symmetric block ciphers are based on a Feistel Cipher Structure • needed since must be able to decrypt ciphertext to recover messages efficiently • bloc k cihiphers lklook like an extremely large substitution • would need table of 264 entries for a 64‐bit block • instead create from smaller building blocks • using idea of a product cipher 1 Claude -
IMPLEMENTASI ALGORITMA CAESAR, CIPHER DISK, DAN SCYTALE PADA APLIKASI ENKRIPSI DAN DEKRIPSI PESAN SINGKAT, Lumasms
Prosiding Seminar Ilmiah Nasional Komputer dan Sistem Intelijen (KOMMIT 2014) Vol. 8 Oktober 2014 Universitas Gunadarma – Depok – 14 – 15 Oktober 2014 ISSN : 2302-3740 IMPLEMENTASI ALGORITMA CAESAR, CIPHER DISK, DAN SCYTALE PADA APLIKASI ENKRIPSI DAN DEKRIPSI PESAN SINGKAT, LumaSMS Yusuf Triyuswoyo ST. 1 Ferina Ferdianti ST. 2 Donny Ajie Baskoro ST. 3 Lia Ambarwati ST. 4 Septiawan ST. 5 1,2,3,4,5Jurusan Manajemen Sistem Informasi, Universitas Gunadarma [email protected] Abstrak Short Message Service (SMS) merupakan salah satu cara berkomunikasi yang banyak digunakan oleh pengguna telepon seluler. Namun banyaknya pengguna telepon seluler yang menggunakan layanan SMS, tidak diimbangi dengan faktor keamanan yang ada pada layanan tersebut. Banyak pengguna telepon seluler yang belum menyadari bahwa SMS tidak menjamin integritas dan keamanan pesan yang disampaikan. Ada beberapa risiko yang dapat mengancam keamanan pesan pada layanan SMS, diantaranya: SMS spoofing, SMS snooping, dan SMS interception. Untuk mengurangi risiko tersebut, maka dibutuhkan sebuah sistem keamanan pada layanan SMS yang mampu menjaga integritas dan keamanan isi pesan. Dimana tujuannya ialah untuk menutupi celah pada tingkat keamanan SMS. Salah satu penanggulangannya ialah dengan menerapkan algoritma kriptografi, yaitu kombinasi atas algoritma Cipher Disk, Caesar, dan Scytale pada pesan yang akan dikirim. Tujuan dari penulisan ini adalah membangun aplikasi LumaSMS, dengan menggunakan kombinasi ketiga algoritma kriptografi tersebut. Dengan adanya aplikasi ini diharapkan mampu mengurangi masalah keamanan dan integritas SMS. Kata Kunci: caesar, cipher disk, kriptografi, scytale, SMS. PENDAHULUAN dibutuhkan dikarenakan SMS mudah digunakan dan biaya yang dikeluarkan Telepon seluler merupakan salah untuk mengirim SMS relatif murah. satu hasil dari perkembangan teknologi Namun banyaknya pengguna komunikasi. -
David T. C~Ai9 736 Edgewater [M J Wichita, Kansas 67230 (USA)
_.., ,.i.'~...< ~~ ':' ..". PASCAL US~RS GROUP Pa.scal.N ews I.. NUMlsER ,< Iq COMMUNICATIONS ABOUT THE PROGRAMMING LANGUAGE PASCAL BVPASCALERS SE PT EMbER .,1980 ~,_v., j : ;,. ~ - EX LIBRIS: David T. C~ai9 736 Edgewater [M J Wichita, Kansas 67230 (USA) ' ... '-" .- . .. .,.- ... ., '-" -'. ..,. ...- .--'- -"--"'.". '. POLICY: PASCAL NEWS (15...Sep...80) * Pascal~ is the official but informal publication of the User's Group. * Pascal Newa contains all we (the editors) kriowabout Pascal; we use it as the vetlICIe to answer all inquiries because our physical energy and resources for answering individual requests are finite. As PUG grows, we unfortunately succumb to the reality of: 1. Having to insist that people ~o need to know "about Pascal" join PUG and read Pascal News - that is why we spend lime to produce, it! 2. Refusing to return phone calls or answer letters full of questions - we will pass the questions on to the readership of Pascal News. Please understand what the collective effect of individual inquirie8lias at the "concentrators" (our phones and mailboxes). We are trying honestly to say: "We cannot promise more that we can do." ' * Pascal News is produced 3 or4 times during a year; usually in March, June, September, and December. * ALL THE NEWS THAT'S FIT, WE PRINT .Please send material (brevity is a virtue) for Pascal News single-spaced and camera-ready (use dark ribbon and 18.5 em lines!) '. - ~ * Remember : ALL LETTERS TO US WILL BE PRINTED UNLESS THEY CONTAIN A REQUEST u TO THE CONTRARY. -.- * Pascal News is divided into flexible sections: o POLICY - explains the way we do things (ALL-PURPOSE COUPON, etc.) EDITOR'S CONTRIBUTION - passes along the opinion and point of view of the D. -
Chapter 3 – Block Ciphers and the Data Encryption Standard
Symmetric Cryptography Chapter 6 Block vs Stream Ciphers • Block ciphers process messages into blocks, each of which is then en/decrypted – Like a substitution on very big characters • 64-bits or more • Stream ciphers process messages a bit or byte at a time when en/decrypting – Many current ciphers are block ciphers • Better analyzed. • Broader range of applications. Block vs Stream Ciphers Block Cipher Principles • Block ciphers look like an extremely large substitution • Would need table of 264 entries for a 64-bit block • Arbitrary reversible substitution cipher for a large block size is not practical – 64-bit general substitution block cipher, key size 264! • Most symmetric block ciphers are based on a Feistel Cipher Structure • Needed since must be able to decrypt ciphertext to recover messages efficiently Ideal Block Cipher Substitution-Permutation Ciphers • in 1949 Shannon introduced idea of substitution- permutation (S-P) networks – modern substitution-transposition product cipher • These form the basis of modern block ciphers • S-P networks are based on the two primitive cryptographic operations we have seen before: – substitution (S-box) – permutation (P-box) (transposition) • Provide confusion and diffusion of message Diffusion and Confusion • Introduced by Claude Shannon to thwart cryptanalysis based on statistical analysis – Assume the attacker has some knowledge of the statistical characteristics of the plaintext • Cipher needs to completely obscure statistical properties of original message • A one-time pad does this Diffusion -
A Tutorial on the Implementation of Block Ciphers: Software and Hardware Applications
A Tutorial on the Implementation of Block Ciphers: Software and Hardware Applications Howard M. Heys Memorial University of Newfoundland, St. John's, Canada email: [email protected] Dec. 10, 2020 2 Abstract In this article, we discuss basic strategies that can be used to implement block ciphers in both software and hardware environments. As models for discussion, we use substitution- permutation networks which form the basis for many practical block cipher structures. For software implementation, we discuss approaches such as table lookups and bit-slicing, while for hardware implementation, we examine a broad range of architectures from high speed structures like pipelining, to compact structures based on serialization. To illustrate different implementation concepts, we present example data associated with specific methods and discuss sample designs that can be employed to realize different implementation strategies. We expect that the article will be of particular interest to researchers, scientists, and engineers that are new to the field of cryptographic implementation. 3 4 Terminology and Notation Abbreviation Definition SPN substitution-permutation network IoT Internet of Things AES Advanced Encryption Standard ECB electronic codebook mode CBC cipher block chaining mode CTR counter mode CMOS complementary metal-oxide semiconductor ASIC application-specific integrated circuit FPGA field-programmable gate array Table 1: Abbreviations Used in Article 5 6 Variable Definition B plaintext/ciphertext block size (also, size of cipher state) κ number -
Symmetric Key Ciphers Objectives
Symmetric Key Ciphers Debdeep Mukhopadhyay Assistant Professor Department of Computer Science and Engineering Indian Institute of Technology Kharagpur INDIA -721302 Objectives • Definition of Symmetric Types of Symmetric Key ciphers – Modern Block Ciphers • Full Size and Partial Size Key Ciphers • Components of a Modern Block Cipher – PBox (Permutation Box) – SBox (Substitution Box) –Swap – Properties of the Exclusive OR operation • Diffusion and Confusion • Types of Block Ciphers: Feistel and non-Feistel ciphers D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 1 Symmetric Key Setting Communication Message Channel Message E D Ka Kb Bob Alice Assumptions Eve Ka is the encryption key, Kb is the decryption key. For symmetric key ciphers, Ka=Kb - Only Alice and Bob knows Ka (or Kb) - Eve has access to E, D and the Communication Channel but does not know the key Ka (or Kb) Types of symmetric key ciphers • Block Ciphers: Symmetric key ciphers, where a block of data is encrypted • Stream Ciphers: Symmetric key ciphers, where block size=1 D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 2 Block Ciphers Block Cipher • A symmetric key modern cipher encrypts an n bit block of plaintext or decrypts an n bit block of ciphertext. •Padding: – If the message has fewer than n bits, padding must be done to make it n bits. – If the message size is not a multiple of n, then it should be divided into n bit blocks and the last block should be padded. D. Mukhopadhyay Crypto & Network Security IIT Kharagpur 3 Full Size Key Ciphers • Transposition Ciphers: – Involves rearrangement of bits, without changing value. – Consider an n bit cipher – How many such rearrangements are possible? •n! – How many key bits are necessary? • ceil[log2 (n!)] Full Size Key Ciphers • Substitution Ciphers: – It does not transpose bits, but substitutes values – Can we model this as a permutation? – Yes. -
Network Security Chapter 8
Network Security Chapter 8 Network security problems can be divided roughly into 4 closely intertwined areas: secrecy (confidentiality), authentication, nonrepudiation, and integrity control. Question: what does non-repudiation mean? What does “integrity” mean? • Cryptography • Symmetric-Key Algorithms • Public-Key Algorithms • Digital Signatures • Management of Public Keys • Communication Security • Authentication Protocols • Email Security -- skip • Web Security • Social Issues -- skip Revised: August 2011 CN5E by Tanenbaum & Wetherall, © Pearson Education-Prentice Hall and D. Wetherall, 2011 Network Security Security concerns a variety of threats and defenses across all layers Application Authentication, Authorization, and non-repudiation Transport End-to-end encryption Network Firewalls, IP Security Link Packets can be encrypted on data link layer basis Physical Wireless transmissions can be encrypted CN5E by Tanenbaum & Wetherall, © Pearson Education-Prentice Hall and D. Wetherall, 2011 Network Security (1) Some different adversaries and security threats • Different threats require different defenses CN5E by Tanenbaum & Wetherall, © Pearson Education-Prentice Hall and D. Wetherall, 2011 Cryptography Cryptography – 2 Greek words meaning “Secret Writing” Vocabulary: • Cipher – character-for-character or bit-by-bit transformation • Code – replaces one word with another word or symbol Cryptography is a fundamental building block for security mechanisms. • Introduction » • Substitution ciphers » • Transposition ciphers » • One-time pads -
Cipher Disk A
Make It@Home: Cipher Disk A. Materials 1 Tack 1 Small Cipher Disk 1 Large Cipher Disk 1 Small Eraser Scissors B. Directions 1. Download and print the Cipher Disk.pdf document. 2. Cut out the two cipher disks. 3. Put the smaller disk on top of the larger disk and stick the tack thru the center of both disks. 4. Stick the sharp end of the tack into the eraser. This will prevent you from sticking yourself while turning the disks to make your ciphers. C. Encrypting A Code 1. Pick a letter from the smaller disk on top - this will be used as the KEY that will be shared between you and your friends to encrypt and decrypt the message. Once you have picked a letter from the smaller disk, line it up with the “A” from the larger disk. Example Key: LARGE DISK: A SMALL DISK: M KEY = A:M 2. Begin encrypting each letter of your secret message. Find the first letter of your message on the larger disk and write down the cipher letter which appears underneath it on the smaller disk. In the example below, A=M, B=L, C=K, etc. LARGE DISK: ABCDEFGHIJKLMNOPQRSTUVWXYZ SMALL DISK: MLKJIHGFEDCBAZYXWVUTSRQPON 3. Continue finding each letter until your message has been encrypted. Once you are finished, send your friend the encrypted message and KEY seperately. PLAINTEXT: MAKING CODES IS FUN CIPHERTEXT: AMCEZG KYJIU EU HSZ NOTE: Make sure your friend knows the KEY so they can use their Cipher Disk to break the code. For a super secure cipher, create a new KEY every time you send a message OR change the KEY every time you encrypt a letter. -
& Electrical Engineering
COMPUTER ARCUTECTURFL Gordon Bell Vice President, Engineering Digital Equipment Corporation & Professor of Computer Science & Electrical Engineering Carnegie-Mellon University (on leave) Abstract Minimal cost computer designs ( i.e. minicomputers) are predicated on using technological cost-performance improvements which occur at an annual rate of 25-305. New applications are thereby feasible with the decreasing costs. A significant number of minicomputers are manufactured in which the cost is constant (or rising), thereby providing more performance (capabilities). The higher performance machines "taket1 their characteristics from the larger, general purpose camputers (e.g. floating point arith- metic, multiprocessors, cache memories and memory management) . The origin and evolution of the minicomputer will be discussed with regard to technology and applications. 7 17178 THR PDP-I? FAMILY AND VAX-Ill780 FOR A LARGE VIRTUAL ADDRESS Gordon Bell Vice President, Engineering Digital Equipment Corporation & Professor of Computer Science & Electrical Engineering Carnegie-Mellon University (on leave) Abstract In the eight years the PDP-11 has been on the market, more than 50,000 units in ten different models have been sold. Although one of the system design goals was a broad range of models, the actual range of 500 to 1 (in price and memory size) has exceeded the design goal. The PDP-11 was designed and first implemented to be a mall minicomputer. Its first extension was to a bigger physical address, memory segmentation for multiprogramming and for higher performance. This part of the talk will briefly reflect the experience in the design process, comment on its success from the point of view of the goals, and its use of technology. -
It Has to Be Good: a History of the Petroleum
It Has to be Good A History of the Petroleum Abstracts Service at The University of Tulsa John A. Bailey Any opinions or interpretation of facts contained in this document are solely those of the author and do not necessarily reflect policies of The University of Tulsa Copyright 2004 John A. Bailey All Rights Reserved Preface This is the story of an uncommon partnership between industry and an academic institution. An industry segment had a need and a prominent university had the vision, talent and determination to fulfill that need. It is also the story of a great deal of hard work, innovation, occasional crisis and cooperation. It is the story of how an organization reflects the characteristics, experience and mindset of the men (and, so far, they have all been men) that led it. This, then, is the story of the Petroleum Abstracts Service at The University of Tulsa that began over 40 years ago. We have attempted to make the story as interesting as possible, a challenge for someone trained as an engineer and computer professional. While some of the information presented here comes from surviving documents, particularly for the early years, much of it is based on memory and occasional hearsay. The reader will also encounter the occasional inside joke. For these offenses, and for any other deficiencies, the author accepts, however begrudgingly, full responsibility. A Need and an Opportunity The late 1950s was not a good time for the petroleum exploration and production industry. Following the resolution of the Suez crisis in 1956, a surplus of crude supply developed and the resulting decline in oil prices began to erode the economics of the industry. -
Cryptology: an Historical Introduction DRAFT
Cryptology: An Historical Introduction DRAFT Jim Sauerberg February 5, 2013 2 Copyright 2013 All rights reserved Jim Sauerberg Saint Mary's College Contents List of Figures 8 1 Caesar Ciphers 9 1.1 Saint Cyr Slide . 12 1.2 Running Down the Alphabet . 14 1.3 Frequency Analysis . 15 1.4 Linquist's Method . 20 1.5 Summary . 22 1.6 Topics and Techniques . 22 1.7 Exercises . 23 2 Cryptologic Terms 29 3 The Introduction of Numbers 31 3.1 The Remainder Operator . 33 3.2 Modular Arithmetic . 38 3.3 Decimation Ciphers . 40 3.4 Deciphering Decimation Ciphers . 42 3.5 Multiplication vs. Addition . 44 3.6 Koblitz's Kid-RSA and Public Key Codes . 44 3.7 Summary . 48 3.8 Topics and Techniques . 48 3.9 Exercises . 49 4 The Euclidean Algorithm 55 4.1 Linear Ciphers . 55 4.2 GCD's and the Euclidean Algorithm . 56 4.3 Multiplicative Inverses . 59 4.4 Deciphering Decimation and Linear Ciphers . 63 4.5 Breaking Decimation and Linear Ciphers . 65 4.6 Summary . 67 4.7 Topics and Techniques . 67 4.8 Exercises . 68 3 4 CONTENTS 5 Monoalphabetic Ciphers 71 5.1 Keyword Ciphers . 72 5.2 Keyword Mixed Ciphers . 73 5.3 Keyword Transposed Ciphers . 74 5.4 Interrupted Keyword Ciphers . 75 5.5 Frequency Counts and Exhaustion . 76 5.6 Basic Letter Characteristics . 77 5.7 Aristocrats . 78 5.8 Summary . 80 5.9 Topics and Techniques . 81 5.10 Exercises . 81 6 Decrypting Monoalphabetic Ciphers 89 6.1 Letter Interactions . 90 6.2 Decrypting Monoalphabetic Ciphers . -
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