Thread: Help using mod

I am trying to encrypt "COMPUTER" using function f(x) = (2x +1)MOD 17

I am unsure what numbers to assign the letters as we are using MOD17 and not MOD 26?

if I use the usual a=0 b=1 etc I get that t and c are both 5!

i get that C and T both encrypt to 7. with a mod 17 encryption system, there is no way to avoid some ambiguity, the encryption itself will be unique, but multiple decryptions will exist (whoever receives your message may decipher it as TOMPUCEA).

thanks a lot for your reply. I got the answer out but thought I had made some mistake. Its just not a good function to encrypt then. Cheers!