Trying to get an RSA algorithm to work but getting stuck where mod is brought in.
If I have the equation
7x = 1 (mod 20)
x = 3 as 21/20 gives a remainder of 1 (this is on an example online)
But I dont understand what is actually happening & my encryption always ends up the same as the number I try to encrypt so the algorithm doesnt work when I try to use my own numbers.
Wikipedia suggests using the Extended Euclidean Algorithm but I dont really understand it.
I'm doing a research qualification & choose to do it on how credit card transactions are secured. But only having AS level maths up to now & it being a project you arent taught where I have to learn & research it all I am struggling.
Any help or advice would be appreciated.