Block ciphers-AES Advanced Encryption Standard 曹天杰 Tianjie Cao ticao@cumt.edu.cn College of Computer Science and Technology, China University of Mining and Technology, Xuzhou China 中国矿业大学计算机科学与技术学院 2003.523
1 曹天杰 Tianjie Cao tjcao@cumt.edu.cn College of Computer Science and Technology, China University of Mining and Technology, Xuzhou, China 中国矿业大学计算机科学与技术学院 2003.5.23 Block ciphers-AES Advanced Encryption Standard
Origins of aes Security Software Hardware Efficiency Efficiency Flexibility
2 Security Software Efficiency Hardware Efficiency Flexibility Origins of AES
Flexibility Additional key-sizes and block-sizes ability to function efficiently and securely in a wide variety of platforms and applications low-end smartcards, wireless: small memory requirements IPSec, atM-small key setup time in hardware B-ISDN, Satellite communication -large encryption speed
3 • Additional key-sizes and block-sizes • Ability to function efficiently and securely in a wide variety of platforms and applications low-end smartcards, wireless: small memory requirements IPSec, ATM – small key setup time in hardware B-ISDN, satellite communication – large encryption speed Flexibility
AES Contest 1997-2001 June 1998 15 Candidates Round 1 from USA, Canada, Belgium, Security France, Germany, Norway, UK, Israel Software efficiency Korea, Japan, Australia, Costa rica Flexibility August 1999 Round 2 5 final candidates Security Mars, RC6, Rijndael, Serpent, Twofish Hardware efficien October 2000 I winner: Rijndael Belgium
4 15 Candidates from USA, Canada, Belgium, France, Germany, Norway, UK, Israel, Korea, Japan, Australia, Costa Rica June 1998 August 1999 October 2000 1 winner: Rijndael Belgium 5 final candidates Mars, RC6, Rijndael, Serpent, Twofish Round 1 Round 2 Security Software efficiency Flexibility Security Hardware efficiency AES Contest 1997-2001
AES In 1999. nist issued a new standard that said BDES Should be used 168-bit key length Algorithm is the same as des 3DES had drawbacks Algorithm is sluggish in software Only uses 64-bit block size In 1997, NiST issued a calls for proposals for the new Advanced Encryption Standard(aes) security strength >=3DES improved efficiency must be a symmetric block cipher (128-bit key lengths of 128. 192 and 256 bits
5 AES • In 1999, NIST issued a new standard that said 3DES should be used – 168-bit key length – Algorithm is the same as DES • 3DES had drawbacks – Algorithm is sluggish in software – Only uses 64-bit block size • In 1997, NIST issued a calls for proposals for the new Advanced Encryption Standard (AES) – security strength >= 3DES – improved efficiency – must be a symmetric block cipher (128-bit) – key lengths of 128, 192, and 256 bits