How to generate a user signature

UserSignature.js

// Import library
const cry = require('thor-devkit/dist/cry')
const Transaction = require('thor-devkit/dist/transaction').Transaction

// User private key.
const originPriv = Buffer.from(
    '2a0cbfe49ea7c18e89b87be4237e1717823fc16b52dc02e91fb30af122fba9b3',
    'hex'
)
// User public address: 0x881Ab2380017870C49a9A114806C05F3CFE406e2
const originAddress = cry.publicKeyToAddress(cry.secp256k1.derivePublicKey(originPriv))

// Construct the hash for signing.
const originHash = tx.signingHash()

// Construct the user signature.
const originSignature = cry.secp256k1.sign(originHash, originPriv)