Crypto_RSA: enable syntax highlight for C code snippet

[LuminousXLB]

\begin{lstlisting}[language=C]

Adding a [language=C] enables the syntax highlight feature of lstlisting, and this may make the code clearer.
It's like this

[kevin-w-du]

This does look better. I will make the changes. Since the changes affect many files, I will do it gradually. I am keeping this issue here until all the files are modified. Thanks.

[LuminousXLB]

Page 13 of this document shows the supported languages. It's a pity that yaml and dockerfile are not supported.
This can be done by minted, but it requires an additional compilation option -shell-escape. Thus I'm not sure if it's a good solution for this project.

[kevin-w-du]

I took a look at minted. It is definitely better than listings, some day, I will start using it, but the change is so significant, and it may break some of the annotation I placed inside the code block, so we will leave the yaml and dockerfile out for the time being.