Update: generate and apply header values when key wrapping

[linuxwolf]

Closes #133

When wrapping keys in JWE, the algorithm can generate a missing value and it'll be applied to the JWE header(s).

For A*GCMKW:

• generate "iv" of 12 random bytes

For PBES2-*:

• generate "p2s" of 16 random bytes
• apply "p2c" of 8192

[panva]

@linuxwolf you have my continuous thanks for this outstanding work!

Shouldn't the changes from #161 that removed the support be reverted? Or is this only for generation and decryption will still remain broken?

The following still fails unless iv is provided, that expected?

const jose = require('.');
const format = 'compact';
const clientKS = jose.JWK.createKeyStore();
const secret = 'GfsT479VMy5ZZZPquadPbN3wKzaFGYo1CTkb0IFFzDNODLEAuC2GUV3QsTye3xNQ';
const alg = 'A128GCMKW';
const base64url = require('base64url');
const crypto = require('crypto');
const payload = JSON.stringify({ foo: 'bar' });
const fields = { alg };

const bufferderived = crypto.createHash('sha256')
      .update(secret)
      .digest()
      .slice(0, 128 / 8);

clientKS.add({
  k: base64url(bufferderived), kty: 'oct',
}).then(() => {
  // fields.iv = base64url(crypto.randomBytes(12)); // doesn't encrypt without iv => Error: invalid iv
  return jose.JWE.createEncrypt({ format, fields }, { key: clientKS.get(), reference: false })
    .update(payload)
    .final();
}).then((crypted) => {
  console.log(crypted)
  return jose.JWE.createDecrypt(clientKS.get()).decrypt(crypted).then(({ payload }) => payload.toString())
}).then(console.log)

PBES2-* i can confirm works as expected, p2s and p2c does not need to be explicitly provided

[linuxwolf]

@panva something is still broken then. I thought I had tests in place, but I also had some hiccups bringin in master. Will take a look, and make better tests for it.

[linuxwolf]

Right now, I see this as the thing that gets node-jose to 1.0.0.

[linuxwolf]

@panva

Latest commit on this PR should address the problems, and tests for it! Would you confirm it meets your expectations?

[panva]

@linuxwolf yes, it's great! 👍