If you’re looking for the equivalent of hash_hmac(‘sha1’, ‘string’, ‘secret’); in JavaScript, then here you go: async function hmac_sha1 (str, secret) { // see https://stackoverflow.com/a/47332317/1134119 let enc = new TextEncoder(« utf-8 »); let key = await window.crypto.subtle.importKey( « raw », // raw format of the key – should be Uint8Array enc.encode(secret), { // algorithm details name: « HMAC », hash: {name: […]