Understanding_Cryptography_Chptr_3---DES

Understanding_Cryptography_Chptr_3---DES - Understanding...

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Understanding Cryptography – A Textbook for Students and Practitioners by Christof Paar and Jan Pelzl www.crypto-textbook.com Chapter 3 – The Data Encryption Standard (DES) ver. Nov 26, 2010 These slides were prepared by Markus Kasper, Christof Paar and Jan Pelzl
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2/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl Some legal stuff (sorry): Terms of Use The slides can used free of charge. All copyrights for the slides remain with the authors. The title of the accompanying book “Understanding Cryptography” by Springer and the author’s names must remain on each slide. If the slides are modified, appropriate credits to the book authors and the book title must remain within the slides. It is not permitted to reproduce parts or all of the slides in printed form whatsoever without written consent by the authors.
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3/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl Content of this Chapter Introduction to DES Overview of the DES Algorithm Internal Structure of DES Decryption Security of DES
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4/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl Content of this Chapter Introduction to DES Overview of the DES Algorithm Internal Structure of DES Decryption Security of DES
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5/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl U Classification of DES in the Field of Cryptology Cryptology Cryptography Cryptanalysis Symmetric Ciphers Asymmetric Ciphers Protocols Block Ciphers Stream Ciphers You are here!
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6/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl U DES Facts Data Encryption Standard (DES) encrypts blocks of size 64 bit . Developed by IBM based on the cipher Lucifer under influence of the National Security Agency (NSA), the design criteria for DES have not been published Standardized 1977 by the National Bureau of Standards (NBS) today called National Institute of Standards and Technology (NIST) Most popular block cipher for most of the last 30 years. By far best studied symmetric algorithm. Nowadays considered insecure due to the small key length of 56 bit. But: 3DES yields very secure cipher , still widely used today. Replaced by the Advanced Encryption Standard ( AES ) in 2000 For a more detailed history see Chapter 3.1 in Understanding Cryptography
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7/29 Chapter 3 of Understanding Cryptography by Christof Paar and Jan Pelzl U Block Cipher Primitives: Confusion and Diffusion Claude Shannon: There are two primitive operations with which strong encryption algorithms can be built: 1. Confusion: An encryption operation where the relationship between key and ciphertext is obscured . Today, a common element for achieving confusion is
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This note was uploaded on 04/01/2011 for the course MA C taught by Professor Anario during the Spring '11 term at Universitat Politècnica de Catalunya.

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Understanding_Cryptography_Chptr_3---DES - Understanding...

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