For your and everyone else's information, in case you or they don't know, that's not how it works.

Single sign on goes:

1. you ask [website] to login, the [website] sends you to google.
2. You log into google and give access.
3. google sends you back to [website], with the authentication that you're [specific google user]. And now you're logged in.

The whole thing requires extremely regular and normal https requests. There is no need for any proprietary blob. The thing that shows up on the website is often a picture that acts as a link. Companies offering single sign on usually ask websites who want to use it, to use specifically prepared images for branding and for users to recognize and go "I have used [company] single sign on before, I can use this safely!"

The only downside to single sign on is that [google] knows that you, [google user] are using [website].