p7m file

p7m digital signature: how to extract the content

You will have to open a file with the p7m extension, that is, those coming from the PEC and signed digitally.
Well! It happened to me a few days ago.
Having no software running the file directly I lost some time to extract both the content and the signatures and verify the correctness.
So not to waste more time with you (but also with me when I recap) I think an article is needed.