You don't access the token from multiple devices, just one(your phone). Google's secret keys are weak but Authy's ones are 256 bits. And finally, Daniel was w

You don't access the token from multiple devices, just one(your phone). Google's secret keys are weak but Authy's ones are 256 bits. And finally, Daniel was wrong about the key derivation, we are actually using PBKDF2. Sorry for the misunderstanding.