On: How Dropbox securely stores your passwords

[tedunangst]

So as a couple comments ask, what if you have to rotate the pepper? There's ways to do that, but sometimes people disengage their brains, and by making the whole scheme a little more complicated and a little more difficult to work with, you entice people to cheat. Like storing the plaintext password in a second column for "rehashing" purposes.

[CiPHPerCoder → tedunangst]

If you encrypt instead of peppering, you just decrypt then re-encrypt with a new key and call it a day.

Peppering has always meant, to me, doing something like this:

  // Hashing
  $preHash = base64_encode(
      hash_hmac('sha512', $password, $_ENV['pepper'], true)
  );
  $storedHash = password_hash($preHash, PASSWORD_DEFAULT);

  // Validation
  $preHash = base64_encode(
      hash_hmac('sha512', $password, $_ENV['pepper'], true)
  );
  if (password_verify($preHash, $storedHash)) {
      // You're in!
  }

To anyone reading this: Don't bother peppering.

[jbrownbridge → CiPHPerCoder]

Alternatively you could just encrypt the already encrypted data with the new key.

[CiPHPerCoder → jbrownbridge]

Wouldn't that require you to retain all compromised keys, and daisy chain the encryption operations?