wasm-signatures / wasmsign2 Goto Github PK

Hey @jedisct1,

I'm toying around using wasmsign and thought it could be nice if Ed25519ph were supported (officially). I'm trying to use it with a system in which there are some cases for which Ed25519 doesn't work, because there's no access to the original signature content bytes in specific code paths, primarily related to signing/verification happening locally vs. remotely.

Based on what's described at https://github.com/WebAssembly/tool-conventions/blob/main/Signatures.md#signature-algorithms-and-key-serialization, additional signature schemes can be supported, but then (at the least) would need some kind of different identifier. Do you think adding Ed25519ph is worth adding to the proposal/documentation?

The current proposal and implementation seem to be doing something similar to prehashing already, although it uses SHA-256, and the "domain specific" context bytes here. Not saying it's exactly the same; just noting some rough similarities.

For the Ed25519ph case, I think it could become something like Ed25519ph(k, sha512(current-hashes-incl-wasmsign-context), context(some-wasmsign-context)). Keeping the current-hashes-incl-wasmsign-context keeps most parts of the verification the same as for Ed25519 with only a small cost in number of bytes. The new context(some-wasmsign-context) could contain the same or other bytes (or just be empty, I guess?).

Hello,

is it possible to verify the signature when loading the wasm in the browser?

Thanks