I don't think signing counts as a modification, or there's some aspect of your query I'm not getting. Either way, the GPL 3 was designed with signing already b

I don't think signing counts as a modification, or there's some aspect of your query I'm not getting. Either way, the GPL 3 was designed with signing already being a thing, GPG had been out for 5+ years. And if signing broke the GPL, I imagine Stallman would have been raising a huge fit about it for decades.