Intro
I got a string original, which was encoded (using the procedure below), then encrypted with rsa and then decoded again, so I'm left with a ciphertext s.
To get back to the original plaintext I'd encode s, then decrypt and then decode again.
Encoding
Each character in s gets encoded (using the function x) like this:
x(A)=0, x(B)=1, ..., x(Z)=25
Then the message, with k amount of characters, gets encoded (using the function y) like this:
encoded_msg = y(s) = x(s0)*260 + x(s1)*261 + x(s2)*262 + ... x(sk)*26k-1
The problem
Now, if i do this for original="ABCD" for example, that would lead to
y(x(original)) = 0 + 1*26 + 2*676 + 3*17576 = 54106.
(encrypt → decrypt → 54106)
decode ?
My question is: If all I got are the functions x and y and a result 54106, how do I decode back to "ABCD"?
