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Function Signature

signTransaction(params: {
  walletMetadata: WalletMetadata;
  transaction: TransactionSerializable;
  password?: string;
  externalServerKeyShares?: ServerKeyShare[];
}): Promise<string>

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Description

Signs an EVM transaction using the wallet identified by the supplied walletMetadata. The SDK is stateless — every call requires walletMetadata. If the wallet was created with backUpToDynamic: true, supply the password so the SDK can recover shares from backup when externalServerKeyShares is omitted.
When you pass externalServerKeyShares (the caller-supplied path), walletMetadata.externalServerKeySharesBackupInfo must also be present — signTransaction throws if shares are supplied but backup metadata is missing. The full walletMetadata returned from createWalletAccount / importPrivateKey already includes it; identity-only metadata from fetchWalletMetadata will be rejected.

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Parameters

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Required Parameters

  • walletMetadata (WalletMetadata) - Non-sensitive wallet metadata persisted from createWalletAccount() / importPrivateKey(). The sender address comes from walletMetadata.accountAddress.
  • transaction (TransactionSerializable) - The transaction to sign (viem format)

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Optional Parameters

  • password (string) - Required if the wallet was created with backUpToDynamic: true. Used for backup decryption when externalServerKeyShares is not provided.
  • externalServerKeyShares (ServerKeyShare[]) - Caller-supplied plaintext shares. If omitted, the SDK recovers from backup using password.

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Returns

  • Promise<string> - The signed transaction as a hex string

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Example

import { authenticatedEvmClient } from './client';
import { parseEther } from 'viem/utils';

const evmClient = await authenticatedEvmClient();

// Load the metadata + shares you persisted at creation time.
const walletMetadata = JSON.parse(await redis.get(`wallet:${accountAddress}`));
const externalServerKeyShares = await vault.read(`wallet:${accountAddress}/shares`);

const signedTx = await evmClient.signTransaction({
  walletMetadata,
  transaction: {
    to: '0xRecipientAddress',
    value: parseEther('0.1'),
    chain: base,
    account: walletMetadata.accountAddress,
  },
  externalServerKeyShares,
  password: 'user-password',
});

console.log('Signed transaction:', signedTx);

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Error Handling

try {
  const signedTx = await evmClient.signTransaction({
    walletMetadata,
    transaction: tx,
    externalServerKeyShares,
    password: 'user-password',
  });
  console.log('Transaction signed successfully');
} catch (error) {
  console.error('Failed to sign transaction:', error);
}