Understanding NTRUEncrypt

Question

I have trouble understanding the NTRUEncrypt algorithm. I read the wikipedia page, but I can not understand the example they gave. When I plug in the product of f and f_p onto wolfram, I do not see how the output relates to any inverse mod p. Can someone please explain the process (and if possible, why it works?).

Answer 1

Nevermind. I understand the process now.

In the corrected output, you have to add the coefficients for X^0 and X^11, X^1 and X^12, and so on, because you are taking it mod (X^11 - 1). The sums of these pairs of coefficients is always equal to 0 mod 3, except for the first one, which is 1 mod 3, as defined by the wikipedia page.