[viem] signMessage fails when using raw property of SignableMessage

[danscan]

Hey there!

I noticed that using @turnkey/viem's signMessage will always fail if you use the raw form of the SignableMessage type.

// succeeds
await turnkeyViemAccount.signMessage({ message: 'hello' });

// fails
await turnkeyViemAccount.signMessage({ message: { raw: stringToHex('hello') } });
await turnkeyViemAccount.signMessage({ message: { raw: hexToBytes('0x68656c6c6f') } });

Looks like it's due to this line, which assumes message is always a string, and casts it to 0x${string}:

sdk/packages/viem/src/index.ts

Line 190 in 89d9999

const hashedMessage = keccak256(message as `0x${string}`);

I believe a quick fix is to replace keccak256(message as `0x${string}`) with hashMessage(message). You can import hashMessage from viem itself, and it accepts a SignableMessage, so it should be exactly what's needed here.

FYI Viem has a nice set of typesafe utilities, and also, as I recently found, common types like Hex so you don't need to type `0x${string}` all over :)

[danscan]

Just confirmed that Viem's hashMessage does what's needed here. Here's my implementation:

import { createActivityPoller, type TurnkeyClient } from "@turnkey/http";
import { hashMessage, signatureToHex, type SignableMessage } from "viem";
import { z } from "zod";

type Options = {
  message: SignableMessage;
  turnkeyClient: TurnkeyClient;
  turnkeyPrivateKeyID: string;
  turnkeySubOrganizationID: string;
}

export async function signMessage({
  message,
  turnkeyClient,
  turnkeyPrivateKeyID,
  turnkeySubOrganizationID,
}: Options) {
  const activityPoller = createActivityPoller({
    client: turnkeyClient,
    requestFn: turnkeyClient.signRawPayload,
  });

  const { result: { signRawPayloadResult } } = CompletedActivitySchema.parse(await activityPoller({
    type: 'ACTIVITY_TYPE_SIGN_RAW_PAYLOAD',
    timestampMs: String(Date.now()),
    organizationId: turnkeySubOrganizationID,
    parameters: {
      privateKeyId: turnkeyPrivateKeyID,
      encoding: 'PAYLOAD_ENCODING_HEXADECIMAL',
      hashFunction: 'HASH_FUNCTION_NO_OP',
      payload: hashMessage(message),
    },
  }));

  const signatureHex = signatureToHex({
    r: `0x${signRawPayloadResult.r}`,
    s: `0x${signRawPayloadResult.s}`,
    v: signRawPayloadResult.v === "00" ? 27n : 28n,
  });

  return signatureHex;
}

const CompletedActivitySchema = z.object({
  result: z.object({
    signRawPayloadResult: z.object({
      r: z.string(),
      s: z.string(),
      v: z.string(),
    }),
  }),
});

[andrewkmin]

Hi @danscan thanks for reporting this! Awesome catch -- we're on it: #117

[andrewkmin]

Hey @danscan the fix has been merged + released. Will be closing this issue now - please let us know if there are any additional issues and we'd be happy to revisit. Thanks again for filing this!