Wrong v value on ethereum signature

[fonstack]

Hey @c0mm4nd

I've using your library and I just realized there is something wrong with the calculation of v.

In one signature it should return v = 0 but instead is returning v = 1. This is basically changing the end of the signature from ...1b to ...1c. Any idea why is this happening?

[c0mm4nd]

The eth sign test passed as shown in commit 8b87d9f
Is there any newer standard for Ethereum signature?

If possible, could you show me your data, including the content hash, privKey, and the expected signature helping me debug?

[fonstack]

I'm testing with this params:

• private key -> e4d7f99de955728c9921a3de9f2bcdaeb54938da0b1179fdd2275d7ce09dd002

• hash hex to be signed -> b6e16d27ac5ab427a7f68900ac5559ce272dc6c37c82b3e052246c82244c50e4 ("Hello, world!")

• expected signature -> 0x96df6608b777f7642e741b97843475ab29981bca31c2f47d657b43ff7b460d2148def6cd02fb866ac45f736dcc6829f1ca34c1f112805eae0c73981aecee94281b with v = 0 (the last 1b)

but I'm getting ->
0x96df6608b777f7642e741b97843475ab29981bca31c2f47d657b43ff7b460d2148def6cd02fb866ac45f736dcc6829f1ca34c1f112805eae0c73981aecee942801

If I use getV() I'm getting 28 => 1c
and the expected is getV() = 27 => 1b

[fonstack]

You can also take a look at this playground using another library and it's indeed returning the signature with ...1b

https://zapp.run/edit/dart-zow060qox06?entry=lib/main.dart&file=lib/main.dart

[c0mm4nd]

https://github.com/simolus3/web3dart/blob/a97de62fbe8ccc04c29d3c726484cccd5a9522fe/lib/src/crypto/secp256k1.dart#L95C1-L112C49

simolus3/web3dart#240

The result from web3dart is not convincing, please try other lib to validate.

[fonstack]

I can also provide you this JS (using viem) playground with the exact same result @c0mm4nd

https://stackblitz.com/edit/node-js-playground-qsoa9p?file=index.js

Please let me know if you need furthers assistance. This package is pretty important to us and we need this to continue our development!

[fonstack]

Hey @c0mm4nd please take a look at teammate’s @josher8a PR. He is solving the issue based on this https://ethereum.stackexchange.com/a/53182

[c0mm4nd]

Thank you and your great team. I have already merged the PR and published a new version on pub.dev https://pub.dev/packages/ecdsa/versions/0.1.1

[fonstack]

I'll close this since it's already solved, thanks sir @c0mm4nd

cc: kudos to @josher8a :3