AES Encryption

Kevin Orr

JT Schratz

AES ENCRYPTION

OVERVIEW

• History

• Algorithm

• Uses

• Brute Force Attack

HISTORY• Before AES, the Data Encryption Standard (DES) became the federal standard in 1977

• DES uses a 56-bit key

• By the late 1990s, however, it was possible to break DES in a matter of several days

• In January 1997, NIST announced a competition for the successor to DES

• NIST – National Institute of Standards and Technology

• The selected the winner was the Rijndael algorithm in October 2000

• Belgian cryptograhers Joan Daemen and Vincent Rijmen

• Formally known as AES – Advanced Encryption Standard

ALGORITHM 10 cycles of repetition for 128-bit keys.12 cycles of repetition for 192-bit keys.14 cycles of repetition for 256-bit keys.

ALGORITHM STEPS - SUB BYTES

• each byte in the state matrix is replaced with a SubByte using an 8-bit substitution box

• bij = S(aij)

SHIFT ROWS• Cyclically shifts the bytes in each row by a certain offset

• The number of places each byte is shifted differs for each row

MIX COLUMNS• Each column is multiplied by the known matrix. For the 128-bit key it is

ADD ROUND KEY• Each byte of the state is combined with a byte of the round subkey using the XOR operation

USES• Government Standard

• AES is standardized as Federal Information Processing Standard 197 (FIPS 197) by NIST

• AES is sufficient to protect classified information up to the SECRET level.

• TOP SECRET information will require use of either the 192 or 256 key lengths.

• Industry

• SSL / TLS

• SSH

• WinZip

• BitLocker

• Mozilla Thunderbird

• Skype

BRUTE FORCE ATTACK• Supercomputer: K Computer (Japan, 2011)

• Speed: 10.51 Pentaflops= 10.51 x 1015 Flops [Flops = Floating point operations per second]

• Flops required per combination = 1000

• Combination checks per second = (10.51 x 1015) / 1000 = 10.51 x 1012

• Seconds in a Year = 31536000

• No. of Years to crack AES with 128-bit Key = (3.4 x 1038) / [(10.51 x 1012) x 31536000]= (0.323 x 1026)/31536000= 1.02 x 1018 years = 1 billion billion years

CONCLUSION• AES has been around for about 12 years and is still a very strong type of encryption

• Only uses four transformations to create the encryption

• Many programs today that have a need for encryption often use AES due to its strength

• The attempted attacks focus on weaknesses or characteristics in specific implementations called “side channel attacks” and not on the algorithm itself

• So far it is uncrackable

SOURCES• http://luxsci.com/blog/256-bit-aes-encryption-for-ssl-and-tls-maximal-security.html

• http://www.technewsworld.com/story/70437.html

• http://www.eetimes.com/design/embedded-internet-design/4372428/How-secure-is-AES-against-brute-force-attacks-

• http://en.wikipedia.org/wiki/Advanced_Encryption_Standard

QUESTIONS