Encryption is just as easy as decryption. Just add the key to the data instead of substracting, and do all the necessary transformations in between.
Wonder if any one can help me. I am trying to set up an excel spread sheet to encrypt a vig using mod 26. I have been able to do the decrypt ie.
using data offset
=mod(data offset - data of vig,26)+1
but because the maths of encryption is more complex, all free info on the web fudges the issue. I haven't explained this very well, have I? but can any one understand what I am on about?
Thanks for the reply Bacterius. I thought is should be as you say adding the data but...
I don't think it is because of my results.
The mod 26 turns the circle when you get to 26 and therefore has direction, not when you get to zero, so if you add the data you get quite a lot of correct encryption but not for all. Does that make sense to any one?