If I wipe my phone, or get a new phone, I still have my phone number and can receive SMS.

If I wipe my phone, I have permanently lost all of my TOTP codes if I wasn't careful and backed them up manually before wiping...

TOTP is great for security conscious and technologically fluent folks... awful for your grandma.

Bitwarden (and probably others) store the TOTP secrets and are persistent. This isn't a recommendation per se, I'm not sure how I feel about it being stored in the cloud, but it is a bit friendlier.

Sure, but this still requires a certain level of "awareness" for this technology.

It's sort of the same problem PGP suffered from. It's technically great, but cumbersome for non-technical people to use (particularly in a safe way), so people will avoid it.

2FA needs to be simple and easy to achieve mass adoption.

Making people install special apps for just one service, or find out one day they're permanently locked out of their facebook account (or far worse) is simply going to hurt adoption.

If your grandmother can't make it work on her own, then it's not good enough. I'm not advocating SMS is the best option for 2FA, I'm just pointing out the alternatives are currently not up to snuff.

> If I wipe my phone, I have permanently lost all of my TOTP codes if I wasn't careful and backed them up manually before wiping...

Do not, ever, store the TOTP seed in your phone! At least not as the one and only location.

I think this is good advice but it also shows why using TOTP as a default 2FA mechanism (instead of SMS) is a tough sell. How many people are set up to store a TOTP seed in a location other than their authenticator app? How many people even know what a TOTP seed is? I would wager that the vast majority of non-HN readers think of TOTP as a QR code that you scan into an authenticator app, if they are even familiar with authenticator apps.

SMS, for all its security shortcomings, is at least something that the vast majority of people understand already.

> SMS, for all its security shortcomings, is at least something that the vast majority of people understand already.

But of course SMS suffers of the same problems as naive use of TOTP: Lose your phone, you're locked out of every account you have.

So in the worst case, TOTP is as bad as SMS. But, with some awareness/education TOTP is far superior if the user doesn't fall into the trap of attaching the TOTP seed to a phone.

i.e. for the aware user, TOTP is far better. For the naive user, TOTP is no worse than SMS. Thus, always favor TOTP.

Email would be preferred. SMS shouldn’t be the default. If I lost my TOTP tokens, I should be able to go through a tougher path with an email verification step to get in to redo my tokens. What I don’t want is for them to send me an SMS to verify me. What if I’m in a different country? What if I don’t have cell service? What if I don’t have access to my phone and that’s why I’m rotating all my stuff?

why? what is your threat model that makes this a problem? are your passwords equally insecure?

Somebody steals your phone. Now you have lost access to all TOTP and you can't log into anything with 2FA.

This isn't about an attacker getting access to your TOTP codes - it's about you losing access to them.

TOTP isn't inherently tied to phones.

No, it's tied to the app because the initial secret is destroyed after you set it up. Every single Authenticator App I've used (which is not all of them admittedly), requires manual backups - typically in some printed form.

All of my other apps automatically back themselves up, or Apple/Google backs things up for me. When I get a new phone or wipe my phone... after logging into all my account I fully expect my Authenticator app to show up on my home screen and have all my codes in there exactly as I left it before.

This is a huge pitfall for the unaware... you will lose all of your codes, and potentially access to whatever services or things they were protecting.

Authy, 1password, bitwarden, and others back themselves up. If not having a cloud backup is a negative for you, pick a TOTP app that does have it - it’s not a failure of TOTP that the few apps you’ve used don’t back up (or you aren’t aware they do).

> No, it's tied to the app because the initial secret is destroyed after you set it up.

TOTP is not tied to any app. When you set it up, save the TOTP seed in a secure place that you control. There is no need to rely on any app, which would be too fragile to consider.

Use 1password or Bitwarden. They correctly back up TOTP secrets to the cloud.

I consider Google Authenticator to be unacceptably bad.

This is good advice, and I will look into Bitwarden for myself personally, but this isn't a great solution for non-techies... which is the problem with anything that is not SMS 2FA.

We all agree SMS 2FA is not as secure as we'd like it to be... but no alternative exists. It's the classic sliding scale between usability and security. The most secure system is one you cannot use... and the most usable system is one with no security. We need something that is very usable, and still secure... perhaps a tall ask but that is indeed what we're after.

Until then... regular people will continue to use SMS for 2FA. We should be happy people are at least comfortable with SMS 2FA instead of not using 2FA at all.

Most of the services provide backup codes when you enable 2FA.

I don't think that's a huge problem.

Even if they don't, you can backup the QR code used to set up the app.

i agree that the authenticator app stuff is fraught for the average user.

> No, it's tied to the app because the initial secret is destroyed after you set it up. Every single Authenticator App I've used (which is not all of them admittedly), requires manual backups - typically in some printed form.

i scan the QR codes with a normal code reader, and then put the information into keepassxc. i can view the secret, generate codes, do whatever, and it's all with decent open source stuff and stored in a file i can back up.

Too many people lose their phone number.

TOTP at least is just a standard so you can either use a client that has backup options, write your own, or whatever. It's better.

It’s much more common to lose your phone than to lose your phone number (in the UK at least - most likely this varies by country).

Do you have Android? iPhones are set to backup automatically to iCloud by default. I don’t even think about backups at all.

I upgraded to an iPhone 13 about 6 months ago and it was almost completely seamless to restore everything to it.

Your authenticator apps won't be backed up. They require you to export them to a QR code or some other printed format... then "restored" once you setup your new phone.

Probably a security policy thing more than a technology thing... but the result is the same. TOTP is dangerous for the wrong user.

For the past several years both macOS and iOS have TOTP built into the password manager. It’s non-obvious how to set it up and doesn’t auto-prompt readily like password management does, but I’ve moved all of my TOTP over and have a backup, it’s synced to all my devices, and I don’t need a dedicated TOTP app.

Wow I never knew this.

That’s up to the developer, it’s not a requirement of TOTP apps.

well that’s not true if you use backups or authy

does your grandma use backups?

Steam is another big one. They require you to use the Steam mobile app and it's the only way to do 2FA - no QR code. I've since dropped 2FA for Steam altogether.

This seems to have changed; you're able to use e-mail MFA (and is what I use for my account).

Let's just hope they don't use _that_ for marketing purposes! ;)

Actually, that option has existed forever, since even before the app-based MFA.

However, if you use the "less secure" email MFA then steam places limits on your account that don't exist with the app MFA, like a forced delay on executing trades.

The Steam 2FA generation has been reverse engineered and you can use it in some password managers. Hardest part is extracting the secret

https://bitwarden.com/help/authenticator-keys/#steam-guard-t...

"upgrade" steam to version 2.1.4 or older and you can use adb backup. Android backup extractor can convert the backup to a standard tar file.

If you've got the steam mobile app for Android for 2fa and want to move to a different app that supports steam 2fa (aegis, winauth, etc), use steam auth on multiple devices, or simply move to a new device without a temporary trade block, version 2.1.4 of the steam app will allow you to perform adb backups; Android backup extractor will allow you to convert the backup to a standard tar file to extract the secrets if you want to.

Unfortunately, Sendgrid and other users of Authy with no alternative 2FA systems in place lock you into the Authy app or SMS as the fallback. There are some, very limited, workarounds for this but still requires you to have the app in Authy.

———————

On a recent find apparently Authy (the app not the sms fallback) has a weird, uh, “feature?”, where my 2fa, for example, for Sendgrid will unlock all of my Sendgrid accounts, which I personally find mildly concerning.

If you load your Sendgrid Authy 2FA on a rooted android phone, you can extract the TOTP secret that powers it under the hood and put it in Bitwarden like you prefer.

Authy used to just be TOTP IIRC - did that change?

Authy has both TOTP functionality and a proprietary system that's different, similar to Symantec VIP or Entrust

Not in consumer context for sure.

Ultimately with any service you’re only protected by your contract and the PR value of a breach of trust. Unless you’re using an open source app and rolling your own sync, an app where trust is paramount (1Password), or one where a misstep is a huge media hit (Apple), you’re at the mercy of that company.

Microsoft fwiw, probably uses location to spot fraud and is unlikely to breach user trust imo.

I have. I worked for an enterprise that used OneLogin could only use the OneLogin Protect app for 2FA. I thought 1Password was broken but I tried a different app with my phone camera and it said the QR code was invalid.

That's configurable in OneLogin, your company just hadn't added more options. I added WebAuthn, Protect and TOTP just this morning.