rel=canonical required for HTTPS?

Question

I'm offering a page through HTTP and HTTPS, both with the same URL scheme. I.e., a page is available as http://www.example.com/page1.html as well as https://www.example.com/page1.html.

Should I add rel=canonical to one of those pages?

Answer 1

Although your question is a bit shorter than this one the accepted answer points to this article which says:

Yes, you can use rel="canonical" for https to http or vice versa. Rel="canonical" is already live in Google's indexing process and has shown results for our trusted testers.

Answer 2

It's not really necessary, but it never hurts to use a canonical URL anyway.