I'm trying to calculate Rijndael key schedule "Rcon" values manually. I know how to calculate each value with the equation
rcon(i) = x^(i-1) mod x^8 + x^4 + x^3 + x^1 + 1, for example:
recon(10) = x^(10-1) mod x^8 + x^4 + x^3 + x^1 + 1 x^(9) mod (x^8 + x^4 + x^3 + x^1 + 1) => x^5 + x^4 + x^2 + x => 0011 0110 => 0x36 (10th number in RCON Table)
i equals to
rcon(0) = x^(-1) mod x^8 + x^4 + x^3 + x^1 + 1
According to "Wikipedia: Rijndael key schedule ~ Rcon", the first value in Rcon table is
0x8d, which most probably is the value for
rcon. I would like to know how it is calculated.
I know how to calculate the
mod on paper and this is exactly how I calculated the
0x36 above. But since the power of
-1 in this case, I am stuck with it. How is
rcon calculated in AES?