Client cannot call the verify function when using phantom wallet

[quangthiennd15]

When I code the frontend using phantom wallet integration to call the function containing the signature verification part using secp256k1

[GuidoDipietro]

Please describe this issue further. Also notice this is just an example repo and not a productive application.

[therohanraghuwanshi]

Hey @GuidoDipietro, I am facing the same issue. I have written a script in anchor through which I am able to verify the message and proceed with next steps but I am not able to do the same when using the phantom wallet for sending the transaction. The same code works in my anchor script but it fails in the browser.

Please help.

[therohanraghuwanshi]

Hey @GuidoDipietro @quangthiennd15 I have found the solution for the signature verification to work with phantom.

You'd need to either change the indes of the instruction in the line below

let ix: Instruction = load_instruction_at_checked(0, &ctx.accounts.ix_sysvar)?;

or you can either have the gas configuration set manually for the instructions to work fine moving the signature verification preinstruction to the 1st index.

`

   const signatureVerificationInstruction =
      anchor.web3.Ed25519Program.createInstructionWithPublicKey({
        publicKey: new PublicKey(data.data.admin).toBytes(),
        message: Uint8Array.from(
          Buffer.from(bs58.decode(data.data.message))
        ),
        signature: bs58.decode(data.data.signature),
      });

    const computeBudgetIx = ComputeBudgetProgram.setComputeUnitPrice({
      microLamports: 0,
    });

    const computeUnitsIx = ComputeBudgetProgram.setComputeUnitLimit({
      units: 200_000,
    });

    await programInstance.methods
      .airdrop(
        new anchor.BN(data.data.amount),
        walletState.ethWalletAddress,
        walletState.fetchWalletAddres,
        Buffer.from(
          Uint8Array.from(Buffer.from(bs58.decode(data.data.message)))
        ),
        Array.from(bs58.decode(data.data.signature))
      )
      .accounts({
        airdropState,
        vault: new PublicKey(VAULT),
        vaultTokenAccount: new PublicKey(VAULT_TOKEN),
        recipientTokenAccount: recipientTokenAddress,
        recipient: provider.wallet.publicKey,
        admin: new PublicKey(data.data.admin),
      })
      .preInstructions([
        signatureVerificationInstruction,
        computeBudgetIx,
        computeUnitsIx,
      ])
      .rpc();

`

[GuidoDipietro]

Hello @therohanraghuwanshi, thanks for your contribution!

I realize now this is due to the fact that Phantom adds preinstructions which mess with the instruction introspection in the Rust code.

This wasn't taken into consideration originally given that, as I said, this is not meant to be a productive application or used from a front end as it is rather just an example repo, and moreover probably because the Phantom preixs weren't a thing back then at all (should check).

Still, if you would like to open a PR with the solution I would be happy to review it.