Yeah, I mean if the goal is the "enterprise" solution, which is usually the solution where the setup, as well as the risk and damages of a break-in, can be shou

Yeah, I mean if the goal is the "enterprise" solution, which is usually the solution where the setup, as well as the risk and damages of a break-in, can be shouldered to another company, then yeah RSA is usually the answer. I was primarily referring to the cryptographic security. Yes, RSA does avoid the transfer of plaintext secrets over the network, but instead you are placing your trust in RSA as a company to not have stored the secrets elsewhere (which, in most cases, is probably just fine). The advantage of U2F is that it uses an asymmetric scheme where a keypair is generated for each authentication endpoint, so the secrets never leave the hardware token in the first place. Compared to RSA SecurID, you would need to have a really severe threat scenario such that you can't even trust RSA with your keys. Of course, U2F is also a much more complicated protocol than say TOTP, and has not existed long enough to stand the cryptographic test of time. To answer your second question, I'm not sure I understand what you mean. TOTP (Google Authenticator), RSA SecurID, and U2F are all different types of 2FA. They could all be combined with Kerberos if that is what you want.