by Professor Edward Schaefer of Santa Clara University in 2003 its purpose is educational, since its key and block size are very small 16bits it is possible for students to encrypt or decrypt a block doing all operations by hand it easier for students to understand the structure AES
MixCol (0010 1110 1110 1110) = 0010 1110 1110 1110 ∗ 1 4 4 1 = = 2 E E E ∗ 1 4 4 1 = (2∗1⊕E∗4) (E∗1⊕E∗4) (2∗4⊕E∗1) (E∗4⊕E∗1) * 1 2 3 4 5 6 7 8 9 A B C D E F 2 2 4 6 8 A C E 3 1 7 5 B 9 F D 4 4 8 C 3 7 B F 6 2 E A 5 1 D 9 9 9 1 8 2 B 3 A 4 D 5 C 6 F 7 E
Columns : MixCol (1111 0110 0011 0011) = 1111 0011 0110 0011 ∗ 9 2 2 9 = = F 3 6 3 ∗ = (F∗9⊕6∗2) (3∗9⊕3∗2) (F∗2⊕6∗9) (3∗2⊕3∗9) = (E⊕C) (8⊕6) (D⊕3) (6⊕8) = (1110⊕1100) (1000⊕0110) (1101⊕0011) (0110⊕1000) * 1 2 3 4 5 6 7 8 9 A B C D E F 2 2 4 6 8 A C E 3 1 7 5 B 9 F D 4 4 8 C 3 7 B F 6 2 E A 5 1 D 9 9 9 1 8 2 B 3 A 4 D 5 C 6 F 7 E