Sign EVM Transactions

Overview

DynamicEvmWalletClient::signTransaction signs an EIP-1559 (Type 2) transaction and returns the signed RLP hex, ready to push directly to any JSON-RPC eth_sendRawTransaction endpoint. If you also want to broadcast in the same call, see sendTransaction. Reach for signTransaction when you need the signed payload out-of-band — co-signing, custom relayers, or batched broadcasts.

Prerequisites

Created an EVM wallet

Build the Transaction

EvmTransaction is an immutable builder backed by BigInteger fields, so values up to uint256 round-trip without precision loss:

import java.math.BigInteger;
import xyz.dynamic.waas.evm.EvmTransaction;

EvmTransaction tx = EvmTransaction.builder()
    .chainId(11155111L)                                       // Sepolia
    .nonce(BigInteger.ZERO)
    .maxFeePerGas(new BigInteger("10000000000"))              // 10 gwei
    .maxPriorityFeePerGas(new BigInteger("1000000000"))       // 1 gwei
    .gasLimit(new BigInteger("21000"))
    .to("0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB")
    .value(BigInteger.ZERO)
    .data("0x")
    .build();

EIP-155 replay protection comes from chainId (already included in EIP-1559 envelopes), so you don’t need to apply the legacy v + 2 * chainId + 8 adjustment yourself.

Sign the Transaction

import xyz.dynamic.waas.evm.opts.SignTransactionOpts;

String signedRlpHex = client.signTransaction(SignTransactionOpts.builder()
    .transaction(tx)
    .walletProperties(walletProperties)
    .externalServerKeyShares(externalServerKeyShares)
    .build()
).join();

System.out.println("Signed RLP: " + signedRlpHex);

signedRlpHex is a 0x-prefixed hex string carrying the full signed transaction envelope — pass it directly to eth_sendRawTransaction on any RPC.

Broadcasting Yourself

If you don’t want sendTransaction to manage signing for you — for example the transaction was signed on a client and your server only needs to relay it — broadcast the signed RLP with the static EvmRpc.sendRawTransaction helper. It needs no wallet, MPC, or key shares:

import xyz.dynamic.waas.evm.EvmRpc;

String txHash = EvmRpc.sendRawTransaction(
    signedRlpHex,
    "https://sepolia.infura.io/v3/<your-key>"
).join();

Or, if you’d rather manage the JSON-RPC client yourself, push the signed RLP through web3j directly:

import org.web3j.protocol.Web3j;
import org.web3j.protocol.http.HttpService;
import org.web3j.protocol.core.methods.response.EthSendTransaction;

Web3j w3 = Web3j.build(new HttpService("https://sepolia.infura.io/v3/<your-key>"));

EthSendTransaction resp = w3.ethSendRawTransaction(signedRlpHex).send();
if (resp.hasError()) {
    throw new RuntimeException("Broadcast failed: " + resp.getError().getMessage());
}
System.out.println("Transaction hash: " + resp.getTransactionHash());

Common Transaction Types

ETH Transfer

EvmTransaction transfer = EvmTransaction.builder()
    .chainId(1L)
    .nonce(nonce)
    .maxFeePerGas(maxFee)
    .maxPriorityFeePerGas(maxPriorityFee)
    .gasLimit(new BigInteger("21000"))
    .to("0xRecipientAddress")
    .value(new BigInteger("100000000000000000"))     // 0.1 ETH in wei
    .data("0x")
    .build();

Contract Interaction

EvmTransaction call = EvmTransaction.builder()
    .chainId(1L)
    .nonce(nonce)
    .maxFeePerGas(maxFee)
    .maxPriorityFeePerGas(maxPriorityFee)
    .gasLimit(new BigInteger("100000"))
    .to("0xContractAddress")
    .value(BigInteger.ZERO)
    .data("0xFunctionSelector...")                   // ABI-encoded call data
    .build();

Learn

Build on the client

Build on the server

Configure

Sign EVM Transactions

Overview

Prerequisites

Build the Transaction

Sign the Transaction

Broadcasting Yourself

Common Transaction Types

ETH Transfer

Contract Interaction

Next Steps

​Overview

​Prerequisites

​Build the Transaction

​Sign the Transaction

​Broadcasting Yourself

​Common Transaction Types

​ETH Transfer

​Contract Interaction

​Next Steps

Overview

Prerequisites

Build the Transaction

Sign the Transaction

Broadcasting Yourself

Common Transaction Types

ETH Transfer

Contract Interaction

Next Steps