Timo Martinson•13mo ago

Where to store this key — and how?

const cryptoKey =
  await crypto.subtle.generateKey({
    name: 'HMAC', hash: 'SHA-512'
  }, true, ['sign', 'verify'])

const cryptoKey =
  await crypto.subtle.generateKey({
    name: 'HMAC', hash: 'SHA-512'
  }, true, ['sign', 'verify'])

3 Replies

Timo Martinson•13mo ago

I want to use it with JWTs

AhDingsHier•13mo ago

You could export the key to/as Base64:

async function generateKeyAsBase64() {
  const key = await crypto.subtle.generateKey(
    { name: "HMAC", hash: "SHA-512" },
    true,
    ["sign", "verify"],
  );
  const keyBuffer = await crypto.subtle.exportKey("raw", key);
  return btoa(String.fromCharCode(...new Uint8Array(keyBuffer)));
}

async function generateKeyAsBase64() {
  const key = await crypto.subtle.generateKey(
    { name: "HMAC", hash: "SHA-512" },
    true,
    ["sign", "verify"],
  );
  const keyBuffer = await crypto.subtle.exportKey("raw", key);
  return btoa(String.fromCharCode(...new Uint8Array(keyBuffer)));
}

Then, e.g., store the base64 string in an environment variable. Converting the string to a key is simple:

async function getKeyFromBase64(base64Key: string) {
  const key = Uint8Array.from(atob(base64Key), (c) => c.charCodeAt(0));
  return await crypto.subtle.importKey(
    "raw",
    key,
    { name: "HMAC", hash: "SHA-512" },
    true,
    ["sign", "verify"],
  );
}

async function getKeyFromBase64(base64Key: string) {
  const key = Uint8Array.from(atob(base64Key), (c) => c.charCodeAt(0));
  return await crypto.subtle.importKey(
    "raw",
    key,
    { name: "HMAC", hash: "SHA-512" },
    true,
    ["sign", "verify"],
  );
}

Should work on deploy as well.

NeTT•13mo ago

I usually write the key to a .env It can then be accessed as an environment variable