@bsv/sdk/src/auth/utils/createNonce.ts

BSV Blockchain Software Development Kit

import {
  WalletInterface,
  WalletCounterparty,
  Base64String,
  OriginatorDomainNameStringUnder250Bytes
} from '../../wallet/Wallet.interfaces.js'
import * as Utils from '../../primitives/utils.js'
import Random from '../../primitives/Random.js'

/**
 * Creates a nonce derived from a wallet
 * @param wallet
 * @param counterparty - The counterparty to the nonce creation. Defaults to 'self'.
 * @returns A random nonce derived with a wallet
 */
export async function createNonce(
  wallet: WalletInterface,
  counterparty: WalletCounterparty = 'self',
  originator?: OriginatorDomainNameStringUnder250Bytes
): Promise<Base64String> {
  // Generate 16 random bytes for the first half of the data
  const firstHalf = Random(16)
  // Create an sha256 HMAC
  const { hmac } = await wallet.createHmac({
    protocolID: [2, 'server hmac'],
    keyID: Utils.toUTF8(firstHalf),
    data: firstHalf,
    counterparty
  }, originator)
  // Concatenate firstHalf and secondHalf as the nonce bytes
  const nonceBytes = [...firstHalf, ...hmac]
  return Utils.toBase64(nonceBytes)
}