Transcript Advance Encryption Standard - National Cheng Kung University

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History
Applications
Attacks
Advantages & Disadvantages
Conclusion
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Based on Rijndael algorithm
Designed by Vincent Rijmen and Joan Daemen
Successor of DES ( Why not Triple-DES )
128-bit key minimum
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15 different designs
5 final nominees
• Rijndael (86 positive, 10 negative)
• Serpent (59 positive, 7 negative)
• Twofish (31 positive, 21 negative)
• RC6 (23 positive, 37 negative)
• MARS (13 positive, 83 negative)
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A standard by NIST On June 2003, AES 128-bit was
approved
Archive and compression
tools for SECRET level document,
and AES 256-bit approved for “TOP
Disk encryption
SECRET” level
Local Area Network security
Programming language
•C
: Cryptography API
• C++
: Botan, Crypto++
• Java
: Java Cryptography Extension (JCE)
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Side channel attack
• Power analysis
• Timing analysis
• Fault analysis
• Acoustic analysis
• Radiation analysis (TEMPEST)
Exhaustive search (Brute force attack)
XSL attack ( Extended Sparse Linearization )
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Published in 2002
Requiring fewer known plaintext
Faster than an exhaustive search
No real-world implementation
“no one knows for certain if XSL can break Rijndael, and no one
knows for certain that XSL cannot break Rijndael either..”
Bruce Schneier, Twofish designer
Advantages
• Safe
Brute Force (128 Bit = 2128 attempts)
Unbreakable, for now..
Disadvantages
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Too simple algebraic structure
Will be used until there is any indication that the
cipher system could be broken.
• Safe for now..
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[1] AES : http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
[2] WinZip AES Encryption Information: http://www.winzip.com/aes_info.htm
[3] AES Implementations: http://en.wikipedia.org/wiki/AES_implementations
[4] Cryptosystem: http://www.cryptosystem.net/aes/
[5] AES Animations: http://www.cs.bc.edu/~straubin/cs38105/blockciphers/rijndael_ingles2004.swf
[6] XSL Attack: http://en.wikipedia.org/wiki/XSL_attack
Thank you for your attention!
Very slow in software
 Unsuitable in limited resources platform
 Only 64 bits block size
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