I saw multiple implementations that looked for a signature, verified it, then just trusted the document as a whole rather than only the part that was signed. So as long as you had any signed SAML doc, you could provide an attention of your choosing and just bundle the signed one somewhere arbitrary inside of it.
replyIt really probably is the worst security specification ever written.
replyIt’s also enormous, I assume from the attempt to have nominally composable parts that could be reused for other flows.
replyIt’s three entire specs bundled as one. One for the XML components, another for the documents you build from them, and another for the authentication flows built on top.
The root problem with SAML is there’s a million and one permutations to do the same thing.
replySigned assertions. Signed messages. Encrypted messages. Encrypted assertions. Sign after normalization. Sign before normalization. Encrypt then sign. Sign then encrypt.
There’s too many ways to do too many things.