**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.
**Why**
In some cases, it might be necessary to run some code right after the user signs in, but before the OTP is sent, and also right before a user signs out.
For example, consider this scenario:
- The app requires the user to confirm their phone number before it gets saved. This confirmation is done by sending an OTP to the phone and asking the user to enter it.
- User mistypes the number, then closes the anonymous browser window, or signs out before confirming
- User signs back in, and OTP is sent to the mistyped number. User is now unable to fully sign in since the OTP is being sent to the wrong number
In order to prevent this scenario, we need to be able to reset the `unconfirmed_mobile` to nil before the OTP is sent, and before they sign out so that they can type it in again.
**How**
Allow the gem user to define an OtpSender class with a `reset_otp_state` method
This makes the gem store a signed cookie for a configurable amount of
time that allows the user to bypass 2FA. Our use-case for this is that
we expire user’s Devise sessions after 12 hours, but don’t want to
force them to authenticate using 2FA every day.
Signed cookies are available since Rails 3. This requires the signing
functionality to be properly configured, but is disabled by setting the
config variable to `0`, the default.