AES S-BOX SUBSTITUTION
INPUT: "SECUREMESSAGE16!"
→
OUTPUT: S-BOX LOOKUP
AES S-BOX LOOKUP TABLE (16×16)
EXAMPLE: LETTER "S"
STEP 1: INPUT VALUE
S
DEC
=
83
HEX
=
0x53
STEP 2: SPLIT HEX DIGITS
0x53
Row =
5
, Col =
3
STEP 3: FIND IN S-BOX
Table shows:
ED
HEX
STEP 4: CONVERT TO DECIMAL
0xED
=
237
DEC
(E × 16) + D = 237
(14 × 16) + 13 = 237
HEX → DECIMAL FORMULA
Example with
0x53
:
• First digit:
5
• Second digit:
3
• Decimal = (5 × 16) + 3
• Decimal =
80
+ 3 =
83