Proton Authenticator

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Website

Short description

Proton Authenticator is a free, open-source two-factor authentication (2FA) app built by Proton, the team behind Proton Mail, Proton VPN, and Proton Pass. It generates time-based one-time codes and offers full privacy, transparency, and choice through open-source code that anyone can inspect. Codes are backed up locally with end-to-end encryption so nothing is readable by anyone else.

Why I think this tool should be added

It matches all the requirements of Privacy Guides.

  1. It uses a hardened version of the Secure Remote Password (SRP) protocol that offers stronger security guarantees against man-in-the-middle (MITM) attacks.
  2. The source code is publicly available. protonpass repositories · GitHub
  3. Available on all platforms - Windows, iOS, Android, and Linux.
  4. The development is active; the latest version for Android on F-Droid was released on Jul 31, 2026.
  5. It’s very easy to use; there’s no need to share any details to use the app properly.
  6. The documentation on how to use it is uploaded on its official site.
  7. Proton Authenticator’s end-to-end encryption guarantees that all cryptographic operations, including key generation and data encryption, are performed locally on the user’s device.
  8. Optional cloud sync — Proton Authenticator can be used without an account. If the user does have a Proton Account, the codes can be securely synced across devices.

Section on Privacy Guides

Multifactor Authentication

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I’ll second this. Early on, they used to have non-optional syncing and I almost lost the data in my account when I tried to use Proton Authenticator to authenticate with my proton account. I had to use Proton Authenticator to login to Proton Authenticator to get access to Proton Authenticator.

Now I use it locally without logging in and prefer it to Aegis. It’s open source and everything, with it even being on F-droid. It’s a very nice option.

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The authenticator meets all the criteria but, personally, I would like to see Proton follow through with their commitment to having the authenticator audited (atleast once) before its added, since Proton seems to have a history of misleading its customers.

Proton Authenticator will also undergo regular independent security audits, and we will share these audit reports publicly as soon as they are available.

Source

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That’s the problem with every ecosystem provider. If anyone is using multiple services from the same provider, they shouldn’t use any of that provider’s services to log into their main account.

I’m already using Ente Photos, and to use Ente Auth, I should create a separate Ente account. The same goes for Proton as well — I’m using their Mail service.

Although there’s no proof, my belief is that Proton might offer better privacy and security compared to Ente, as they offer various types of services, including Mail, Password Manager, VPN, Cloud Storage, etc., whereas Ente only offers cloud-based services (Photos and Locker). Again, that’s just my thought — I don’t have any proof of this claim.

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I totally agree with your points. But if you look closely at the recommended Multifactor Authentication page, there’s only one recommended TOTP app — Ente Auth. Aegis is available only on Android, so it might not be an option for everyone, especially for someone using iOS. The most recommended TOTP app on iOS is 2FAS, which doesn’t offer actual cloud sync, also not as privacy friendly as others. So Ente becomes the only option.

In other categories, like Mail, Cloud Storage, etc., there are multiple PG recommended services, so if anyone doesn’t want to use a particular service, they have other choices. But that’s not possible with MFA.

In this situation, Proton Authenticator looks more promising as an alternative option. It’s available on all platforms, open source, and offers optional cloud sync — probably a perfect fit for PG’s recommended MFA.

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Relevant Introducing Proton Authenticator: Secure 2FA, your way - #64 by Equinox

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@night_driver

That’s the problem with every ecosystem provider. If anyone is using multiple services from the same provider, they shouldn’t use any of that provider’s services to log into their main account.

I assumed that Authenticator would work locally on my device, as there is no reason to log into an “ecosystem” to get an authenticator code. Thankfully it now works the way I assumed it did and I do not sync the Proton Authenticator codes.

I’m not sure what to think about the plain text claim. If that were the case, I wouldn’t use it, but it doesn’t sound like it is now or ever was true on Android? If there haven’t been major issues for over a year it sounds like it could be time to start considering it.

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Fair enough. Personally, I don’t love these points based on the number of current reccomendations. I don’t believe that should ever be a factor.

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It looks like there had an issue where it stored 2FA seeds inplain text which has been fixed already. So, do you guys add it to the recommended Multifactor Authentication page?

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This Authenticator works offline. But in my case, due to my cross-device usage — more specifically, multi-mobile usage — I have to use a cloud-based 2FA app. I don’t carry both my mobiles all the time, just any one of them. So to log into my online accounts, I need the 2FA installed on both of my mobiles.

For two devices, cloud sync might not be that necessary, but I’m not in the habit of updating the TOTP database every time I add a new 2FA seed.

Now, among cloud-based 2FA apps, there are two privacy friendly choices: Ente and Proton. As I mentioned in my earlier comment, although there’s no proof, my belief is that Proton might offer better privacy and security compared to Ente, as they offer various types of services, including Mail, Password Manager, VPN, Cloud Storage, etc., whereas Ente only offers cloud-based services (Photos and Locker). Again, that’s just my thought — I don’t have any proof of this claim.

Honestly, cloud-based TOTP services look like a charity from providers — they can’t introduce a paid plan here that would generate revenue for them, but over time, they still have to maintain strong security and privacy in their 2FA apps and store the 2FA seeds of users on their storage which cost them few extra.

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So, what do you think is the reason it’s not on the recommended Multifactor Authentication list?

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do you mean other then that this is the first time its been put up as a tool suggestion?

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I agree with you — yes, both Proton and Ente Authenticator can be used offline.

But in my use case, I have to use something with cloud sync, due to using two mobile devices. I still can’t build the habit of updating the database on the second device whenever I make a new entry on the first. Also, I don’t carry both devices all the time, so using a local 2FA app was becoming an issue for me. Though I try my best to back up all databases monthly, sometimes I miss it too.

So, for me, the only PG-recommended Multifactor Authentication app is Ente Auth. Aegis is only available on Android, which is another problem. I believe having choices is always better than a single option. After Ente Auth, the only privacy-friendly, cloud-based (optional) 2FA service left is Proton Authenticator.

The only con of Proton Authenticator, or more specifically all Proton services, is that if you create a Proton account with your existing email address and ever delete that account, you can’t open a new Proton account with that same email address — this restriction doesn’t exist with Ente services.

Yes, you’re probably right — other than its age, I can’t find anything negative about Proton Authenticator. Hopefully the team will consider it now.

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I couldn’t find any post regarding this topic so I made one.

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Hey, what’s your opinion on Proton Authenticator? It meets all the requirements of PG to be on the recommended list. What do you think?

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Proton Authenticator could be a good addition. The main thing to check is whether its iCloud sync is E2EE. I don’t think the app being relatively new or not having an audit yet should be an issue.

I understand that you’re trying to compare Proton Authenticator with other 2FA apps to explain why it’s a valuable addition, but if you compare it specifically with 2FAS Auth I think the differences are smaller than you suggest.

First of all, Proton Authenticator does offer iCloud sync (just like 2FAS), as well as sync through Proton Cloud. Proton Cloud requires a Proton account, while iCloud sync doesn’t (same with 2FAS, no account required for iCloud sync and for Google Drive sync). However, it’s not clear to me whether Proton’s iCloud sync is E2EE, since I haven’t found any public documentation confirming this (while 2FAS confirmed their iCloud sync and Google Drive sync are both E2EE).

So I think Proton Authenticator could be a nice addition after checking a few things, especially if you’re already using Proton services, but saying that 2FAS doesn’t offer cloud sync or isn’t as privacy friendly is not accurate.

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From my research, Proton Authenticator meets all the requirements to be on PG’s recommended MFA list. Yes, the security audit could still turn out negative, but Proton has already planned for that too —

“As with our other services, Proton Authenticator will also undergo regular independent security audits, and we will share these audit reports publicly as soon as they are available.” — From The Proton Authenticator security model

Nah, I never wanted to compare it with 2FAS but with Ente Auth. Both Aegis (on Android) and 2FAS follow a different model, where users can optionally set up cloud sync with their own preferred cloud storage, whereas Ente Auth and the newer Proton Authenticator both offer similar functionality but with the addition of their own servers as for cloud synchronization. To use either Ente Auth or Proton Authenticator with their own servers for syncing, users have to create an account with that provider. In my eyes, Ente Auth and Proton Authenticator are nearly the same, just from two different well-known privacy providers.

That’s the reason I’ve made another post When should I pick Proton Authenticator over Ente Auth? where you commented already.

I’ve found these statements from The Proton Authenticator security model —

“Proton Authenticator secures your data with end-to-end encryption, even when you enable device sync.”

“All cryptographic operations occur locally on your device, and any data transmitted to the server is always encrypted. This means that your unencrypted data cannot be accessed by Proton or shared with any third parties. Proton servers never have access to your unencrypted data, including your Proton Account password.”

I believe these statements are enough to suggest that Proton’s iCloud sync might also be E2EE.

Nah, it’s not. There’s already a post where someone suggested adding 2FAS to PG’s recommended MFA list, and that suggestion was rejected because iCloud sync is not E2EE. 2FAS Auth (TOTP App)

I think exactly the opposite — if someone isn’t using multiple Proton services (especially the main ones), Proton Authenticator can be a great choice for them. The same goes for Ente Auth. My reason for preferring Proton Authenticator is that I’m already using Ente Photos and don’t want to use the same account to store my TOTP seeds. I mentioned this concern in my second post.

I wasn’t updated about 2FAS, so sorry for my mistakes. I read some online comments claiming 2FAS isn’t as secure as Aegis, and that’s where I mistakenly assumed it probably wasn’t good for privacy.

Also, I really like 2FAS’s approach of accessing TOTP codes through its browser extension without needing any cloud dependency. That’s what I meant by “doesn’t offer traditional cloud sync.” The possibility of using cloud sync via third-party cloud services never crossed my mind back then.