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 b ij = S(a ij )

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: Pentaflops= x Flops [Flops = Floating point operations per second] Flops required per combination = 1000 Combination checks per second = (10.51 x ) / 1000 = x Seconds in a Year = No. of Years to crack AES with 128-bit Key = (3.4 x ) / [(10.51 x ) x ] = (0.323 x )/ = 1.02 x 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 against-brute-force-attacks-

QUESTIONS