Interesting. I also went through this sign up recently and thought it was weird that it didn’t require gov.br.

But it asked me for my voter ID and the receipt numbers of my last 2 annual tax forms, which are very secret and somewhat in line with the scope of permissions I got (read-only permissions of tax documents). Write permissions required a digital certificate.

I will report this :)

There is a gov.br and digital certificate option, but they are not mandatory.

> the receipt numbers of my last 2 annual tax forms, which are very secret and somewhat in line with the scope of permissions I got

I see.

I wouldn't call them "very secret". All of my accountants have access to this information, as do several of my family members. I wouldn't be surprised if those things eventually leaked in some government breach either.