EU law only excludes patents for software “as such.” https://www.iam-media.com/regionindustry-guide/patents-in-eu.... You can still patent inventions embodied primarily in software so long as it’s in the context of an industrial or consumer application. So you can’t patent RSA, but you can patent a phone that uses RSA to securely transfer data.

Since the Supreme Court’s Alice decision in 2013, which tightened the longstanding exclusion to patentability for “abstract ideas,” it’s probably slightly harder to get (or keep) a software patent in the US than in the EU. Just because US courts are more willing to look past hardware aspects of an invention to see if the “gist” of the invention is an abstract idea implemented in software.