What is a Second Factor?
Answer: Two Factor Authentication is a method of confirming a user's identity by requiring the user to present two pieces of evidence ("factors") to an authentication mechanism. In our system, the first factor is a password (something the user knows), while the second factor is a token generated by software on the user's mobile device (something the user possesses).
What do I need in order to obtain a second factor token?
Answer: In order to obtain a second factor token, you will need a mobile device with a camera. On that mobile device, you will then need to install Google Authenticator (or another QR code reader application that implements the Time-based One Time Password algorithm) on your mobile device. See also Setting Up Two-Factor Authentication.
Can I use an SSH key pair as an alternative second factor?
Answer: We do not support SSH keys as a second factor and we have no plans to implement SSH key-based authentication. Only time-based codes are currently valid.
I have a new mobile device. How do I transfer my old second factor onto my new device?
Answer: There is currently no easy way to transfer your old second factor onto a new device. You will have to request a new second factor (see below).
Answer: See article here.
Can I use the same Second Factor again?
Answer: No. You can only use each Second Factor code once and must then wait for a new Second Factor to cycle. Attempting to use the same Second Factor will cause your Authentication to fail.