Facundo Medica 644f906966 refactor: (secp256k1) cleaner way to check for lower S form signatures (#13884) ... ## Description TLDR; check for `s.IsOverHalfOrder()` with less steps Before this PR: ```go // parse the signature: signature := signatureFromBytes(sigStr) // Reject malleable signatures. libsecp256k1 does this check but btcec doesn't. // see: f9401ae011/crypto/signature_nocgo.go (L90-L93) // Serialize() would negate S value if it is over half order. // Hence, if the signature is different after Serialize() if should be rejected. modifiedSignature, parseErr := ecdsa.ParseDERSignature(signature.Serialize()) if parseErr != nil { return false } if !signature.IsEqual(modifiedSignature) { return false } ``` It's serializing the signature into a new variable and then comparing if both are equal. Inside `Serialize()` we have: 5d537320a0/dcrec/secp256k1/ecdsa/signature.go (L88-L95) ```go // Ensure the S component of the signature is less than or equal to the half // order of the group because both S and its negation are valid signatures // modulo the order, so this forces a consistent choice to reduce signature // malleability. sigS := new(secp256k1.ModNScalar).Set(&sig.s) if sigS.IsOverHalfOrder() { sigS.Negate() } ``` Before btcec update to v2: Until btcec update this was simpler because S was exported in the signature: ed9cd41396 (diff-30a6b594e157a12a28bf8a26f65ab4de1dc3c65c8419e5756f0b9c25d9ce1a93L46) ```go if signature.S.Cmp(secp256k1halfN) > 0 { return false } ``` Closes: #XXXX --- ### Author Checklist *All items are required. Please add a note to the item if the item is not applicable and please add links to any relevant follow up issues.* I have... - [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title - [ ] added `!` to the type prefix if API or client breaking change - [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting)) - [ ] provided a link to the relevant issue or specification - [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules) - [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing) - [ ] added a changelog entry to `CHANGELOG.md` - [ ] included comments for [documenting Go code](https://blog.golang.org/godoc) - [ ] updated the relevant documentation or specification - [ ] reviewed "Files changed" and left comments if necessary - [ ] confirmed all CI checks have passed ### Reviewers Checklist *All items are required. Please add a note if the item is not applicable and please add your handle next to the items reviewed if you only reviewed selected items.* I have... - [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title - [ ] confirmed `!` in the type prefix if API or client breaking change - [ ] confirmed all author checklist items have been addressed - [ ] reviewed state machine logic - [ ] reviewed API design and naming - [ ] reviewed documentation is accurate - [ ] reviewed tests and test coverage - [ ] manually tested (if applicable)		2022-11-23 17:16:00 +00:00
..
ed25519	feat: Add proto annotations for Amino JSON (#13501)	2022-11-07 22:51:51 +00:00
internal	chore: gofumpt (#11839)	2022-05-19 10:55:27 +02:00
multisig	fix: .String() panics when pubkey is set on a BaseAccount (#13838)	2022-11-14 14:56:18 +00:00
secp256k1	refactor: (secp256k1) cleaner way to check for lower S form signatures (#13884)	2022-11-23 17:16:00 +00:00
secp256r1	refactor: migrate to cosmos/gogoproto (#13070)	2022-09-08 17:27:48 +00:00