Validate secp256k1 ethereum signature?

Question

I’m working on an anchor-lang project to validate secp256k1 ethereum signature. I used secp256k1_recover program docs as a reference for this code. The problem is that the public key I get from the recovery does not match the one that signed the signature. Is there a mistake in my code or did I misinterpret how the recovery operates? I appreciate your help!

use solana_program::secp256k1_recover::{secp256k1_recover};

declare_id!("3PxEqHbGAWZthkyuJvtTjjwYSQ3HRGJVyk8MbjnZP2mt");

#[program]
pub mod solana_treasury {
    use super::*;

    pub fn recover(ctx: Context<New>) -> Result<()> {
        let eth_pubkey = "026f0a0eac8db33cebd88516ccbfafc148cd97abfe217e456c4f47f0478b1b443d";

        // ethers.solidityPackedKeccak256(['string'],["some_message"])
        let message = "69ee7a3423fa9be01fa80a47dffc9c3135fdccaab0ca5d5c4fbc3459b66c271e";

        // Buffer.concat([sig.r, sig.s]).toString('hex'))
        let signature = "5bf05d6ede6316f675a3d0ad0896db0473aaa6084a1c373046fc5ea2a285edd81b0dfc8c5bb6bb0affff58fbc4c16f73b757414b0af05ab4bc139864903bb81b";
        
        // sig.v - 27
        let recovery_id = 0;

        let recovered_pubkey = secp256k1_recover(
            &message.as_bytes(),
            recovery_id,
            &signature.as_bytes(),
        )
        .map_err(|_| ProgramError::InvalidArgument)?;

        // 58a8a3bd63db626497e1b4c09fb3119257c2bd0c651084eac0c038ad49bec874e380efbb5f8232aceae2383b9a1bbc22e936121ebaf83ff880801232327380e3
        let recovered_pubkey_hex = hex::encode(recovered_pubkey.0);

        msg!("Generated Recovered PubKey: {}", recovered_pubkey_hex);

        if eth_pubkey == recovered_pubkey_hex {
            msg!("Public Key Match!");
        } else {
            msg!("Public Key Doesn't Match!");
        }
        // value from recovered_pubkey_hex:
        // 58a8a3bd63db626497e1b4c09fb3119257c2bd0c651084eac0c038ad49bec874e380efbb5f8232aceae2383b9a1bbc22e936121ebaf83ff880801232327380e3

        // eth_pubkey should equals to recovered_pubkey_hex ?

        Ok(())
    }
}

#[derive(Accounts)]
pub struct New {}

Answer 1

The instruction expects it'll receive raw bytes, and not a hex string, so you'll also need to decode the hex strings as bytes:

        let recovered_pubkey = secp256k1_recover(
            &hex::decode(&message).unwrap(),
            recovery_id,
            &hex::decode(&signature).unwrap(),
        )
        .map_err(|_| ProgramError::InvalidArgument)?;