I didn’t understand the division :( And how to compute the inverse?
@vitcermak7737
3 жыл бұрын
When you multiply a number and its inverse in modular arithmetics, you get number 1. In equation: n * n ^ (-1) mod p = 1 mod p. And that is pretty much it. Lets say we have number x = 15 in modulo p = 29. No point in trying 1, 1 * 15 = 15 and 15 mod 29 is 15. 2 * 15 = 30 and 30 mod 29 is 1, so there, we've found it, 15^(- 1) in modulo 29 is 2.
@ifowl
2 жыл бұрын
You can find a multiplicative inverse table for GF(2^8) and use that to find the inverse. Which makes polynomial division in AES Galois fields much easier. Just look up the inverse in that table and then multiply by it.
@baharehshahpar8674
2 жыл бұрын
Thanks, it was a big help exactly before my exam :)
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