ProtocolService

ProtocolService provides a set of stateless APIs for constructing and broadcasting blockchain-specific cryptographic payloads.

The central sequence of API invocations is constructing, signing, and broadcasting a transaction. Signing a transaction requires the use of MPCKeyService or an external signing mechanism, because ProtocolService is stateless and signing algorithms require a private key (i.e., user state).

ProtocolService, however, can be used to construct, and then subsequently, broadcast a transaction.

Sample Code

The following code snippet demonstrates how a transaction to transfer Ethereum from one address (the sender) to another (the recipient) is constructed and broadcast.

info

The code snippet assumes the existence of a keyManager with a CreateSignature API. In reality, you would use the MPCKeyService’s CreateSignature method in coordination with the WaaS SDK.

sendAmount := big.NewInt(0.75 * params.Ether).String()
feeAmount := big.NewInt(10 * params.Gwei).String()

 // 1. Construct an unsigned transfer transaction.
 constructTxReq := &protocols.ConstructTransferTransactionRequest{
     Network:   "networks/ethereum-mainnet", // The resource name of the Ethereum Mainnet Network.
     Asset:     "networks/ethereum-mainnet/assets/2f26f7f2-6bc4-5669-9759-57a8743bff2d", // The resource name for the ETH Asset.
     Sender: "0x974CaA59e49682CdA0AD2bbe82983419A2ECC400",
     Recipient: "0x4ba6b8F1eBc3c14233F7917c721A64b2DA1b80C6",
     Amount:    sendAmount,
     Nonce:     0,
     Fee:       feeAmount,
 }

tx, _ := client.ConstructTransferTransaction(ctx, constructTxReq)

 // 2. Create a signature. Here we assume the existence of a keyManager with a CreateSignature
 // API that ouputs a signature. In reality you would use a combination of the MPCKeyService
 // and the WaaS SDK to produce this signature, but we abstract out that complexity here.
 sig, _ := keyManager.CreateSignature(ctx, tx, ...)

// Set the signature on the Transaction.
tx.RawSignedTransaction = sig


 // 3. Broadcast the transaction.
 broadcastReq := &protocolsRpc.BroadcastTransactionRequest{
       Network:     "networks/ethereum-mainnet",
       Transaction: tx,
   }

 broadcastTx, _ := client.BroadcastTransaction(ctx, broadcastReq)