Sign Message

Make sure you initialize Blocto SDK first

Once your app is connected to Blocto wallet, it can sign message on behalf of the user, with the user's permission.

To sign a message, the app must specify the sign type. All available types are listed below.

Sign Type	Type	Message
ETH Sign	EvmSignType.ETH_SIGN	hex string (0x prefix)
Personal Sign	EvmSignType.PERSONAL_SIGN	plain string
Sign Typed Data v3	EvmSignType.TYPED_DATA_V3	json string
Sign Typed Data v4	EvmSignType.TYPED_DATA_V4	json string
Sign Typed Data (currently identical to Sign Typed Data v4)	EvmSignType.TYPED_DATA	json string

// Sign message based on specific chain

BloctoSDK.evm.signMessage(
    context = context,
    blockchain = Blockchain.ETHEREUM,
    fromAddress = address,
    signType = [EvmSignType.ETH_SIGN/EvmSignType.PERSONAL_SIGN/...],
    message = message,
    onSuccess = { signature ->
        // get signature
    },
    onError = { error ->
        // handle error
    }
)

For dApps relying on signMessage for off-chain authentication, Blocto follows EIP-1654. To verify the signature, you need to call a method on the wallet contract to check if the signature came from a rightful owner of the wallet contract.

// Example code by using web3j

// hash: hash of data (message) to be signed
// signature: signature byte array associated with hash

fun verifySignature(hash: ByteArray, signature: ByteArray): Boolean {
    val web3j = Web3j.build(HttpService(rpcUrl))
    val function = Function(
        "isValidSignature",
        listOf(Bytes32(hash), DynamicBytes(signature)),
        listOf<TypeReference<Bytes4>>()
    )
    val encodedFunction = FunctionEncoder.encode(function)
    return web3j.ethCall(
        Transaction.createEthCallTransaction(
            address,
            address,
            encodedFunction
        ),
        DefaultBlockParameterName.LATEST
    ).send().value.orEmpty() == ERC1271_MAGIC_VALUE
}