Hi!
 
So, I did it!
Before the end of the year, as promised.

S/MIME encryption, decryption, signing and signature verification works.
Of course, this is not the final version.  ))

3 modules of RC were changed. I had to add some new hooks and use one deprecated hook.

I made a separate plugin to work with certificates and keys. Now I have a very simple plugin that uses files to store keys and certificates.
 
I hope that the developers of the RC show interest in my work.

I am also ready to transfer texts and discuss the work done.

If this work is interesting only for me, this letter - the last one I'm posting here.

Sorry to trouble you,
           Vladimir Gorpenko