Understanding_Cryptography_Chptr_4---AES

Understanding_Cryptography_Chptr_4---AES - Understanding...

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Unformatted text preview: Understanding Cryptography by Christof Paar and Jan Pelzl www.crypto-textbook.com Chapter 4 – The Advanced Encryption Standard (AES) ver. October 28, 2009 These slides were prepared by Daehyun Strobel, Christof Paar and Jan Pelzl Chapter 4 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 Christof Paar and Jan Pelzl. • 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. 2/28 Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl Content of this Chapter • Overview of the AES algorithm • Internal structure of AES • Byte Substitution layer • Diffusion layer • Key Addition layer • Key schedule • Decryption • Practical issues 3/28 Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl Content of this Chapter • Overview of the AES algorithm • Internal structure of AES • Byte Substitution layer • Diffusion layer • Key Addition layer • Key schedule • Decryption • Practical issues 4/28 Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl U Some Basic Facts • AES is the most widely used symmetric cipher today • The algorithm for AES was chosen by the US National Institute of Standards and Technology (NIST) in a multi-year selection process • The requirements for all AES candidate submissions were: • Block cipher with 128-bit block size • Three supported key lengths : 128, 192 and 256 bit • Security relative to other submitted algorithms • Efficiency in software and hardware 5/28 Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl U Chronology of the AES Selection • The need for a new block cipher announced by NIST in January, 1997 • 15 candidates algorithms accepted in August, 1998 • 5 finalists announced in August, 1999: • Mars – IBM Corporation • RC6 – RSA Laboratories • Rijndael – J. Daemen & V. Rijmen • Serpent – Eli Biham et al. • Twofish – B. Schneier et al. • In October 2000, Rijndael was chosen as the AES • AES was formally approved as a US federal standard in November 2001 6/28 U AES: Overview The number of rounds depends on the chosen key length: Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl Key length (bits) Number of rounds 128 10 192 12 256 14 7/28 U AES: Overview Chapter 4 of Understanding Cryptography by Christof Paar and Jan Pelzl • Iterated cipher with 10/12/14 rounds • Each round consists of “Layers” 8/28 Chapter 4 of...
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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_4---AES - Understanding...

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