Direct OTP codes are ones that are delivered directly to
the user (e.g. SMS) via send_two_factor_authentication_code.
These are randomly generated, short lived, and stored
directly in the database.
TOTP (and the rotp gem) is now only enabled for those user
that have a shared secret (user.create_otp_secret).
**Why**:
To provide an additional layer of security.
The TOTP spec (RFC 6238) recommends encrypting the keys.
http://tools.ietf.org/html/rfc6238
**How**:
Borrow the encryption code from the `attr_encrypted` gem and use it to
encrypt and decrypt the `otp_secret_key` attribute.
Allow users to add encryption by passing in `encrypted: true` to
`has_one_time_password`. This provides backwards-compatibility for
existing users of the gem.
See the README updates for more detailed instructions for both new
and existing users.
Przemyslaw Mroczek
Sam Clegg
Moncef Belyamani
Jack Turnbull
Matt Mueller
Carlos Vilhena