Verify threshold ecdsa signatures with RustCrypto #23
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR changes two things that were stopping our signatures from validating with rustcrypto:
hash_messageto serialize using big endiansfrom the threshold signature before calling RustCrypto verifyThe normalization of
sis done by computing-s mod ORDERifs >= ORDER / 2. This is OK to do since bothsand-s mod ORDERare valid for the signature, don't really know why this is, but ECDSA on wiki also remarks this.It was kind of funny - I first fixed the hash, and could see that the test was passing about half of the times. Then I found this check, that they perform during verification. There's a link in the doc string for
normalize_swhich describes why they do this.