What is "side-information effects" in coding and decoding techniques?

Question

something related signal encryption

Answer 1

We can use prime numbers to code example

a b c d e f g h i j
2 3 5 7 11 13 17 19 23 29

to write: be deaf we code: 3,11,__, 7,11,2,13

we send the prime numbers to the recipient and he would decode.

Side information effects would be: time wasted in understanding the number sequence or writing the prime numbers.

Other algorithms can be however used and the encryption code must be understood by both parties

Answer 2

From what I remember from information theory, side information has more to do with the statistics of the channel. Coding/Decoding must use an agreed upon method.