Questions tagged [totp]

Time-based One-time Password Algorithm

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TOTP code with unicode character?

I was signing up for an app for a credit card I have and I encountered an SMS 2FA format I had never seen before. The code was 47𝞍⅗ - that is two digits then capital Phi then the fraction three-...
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Is a TOTP with RFC 6238 and a password in a manager 2FA? [duplicate]

For example Microsoft Outlook web based email service can be configured to require both a username/password combination and a time-based one-time password (TOTP) generated by the algorithm described ...
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Why we need complicate truncation for the OTP?

If we assume that Time based OTP generates the OTP using the hash function like SHA-3. Then, the generated OTP would Hash(Secret, Shared time). We want a shortened string rather than a full hash ...
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Is Time-based one-time password (TOTP) sufficiently secure as another factor of authentication?

Given the increasing widespread adoption of Time-based one-time password (TOTP) in view of SMS OTP hacks, Is Time-based one-time password (TOTP) sufficiently secure as another factor of authentication,...
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How is totp considered 2fa?

I was wondering about the design of totp and 2fa. I learned that 2fa is any 2 of the following authentication methods: Something you know (e.g. a password) Something you have (e.g. an email address) ...
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Storing OTP seeds in password manager [duplicate]

I am storing my passwords in a password manager (keepass). Also I am using keepass to set up one-time passwords for some accounts. Keepass is storing the seeds of the OTP's in its database. If my ...
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Historical examples of breached TOTP secrets?

While reading about password breaches, it occurred to me; where are the TOTP shared secret breaches? Because TOTP relies on a shared secret (unlike say U2F) the server has a copy of the shared secret, ...
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Using Public Key Cryptography for improving 2FA?

When using 2-factor-authentication using plain TOTP, the secret is stored on both the client and the server. This in turn means, that anyone with access to the database (and a key for it) knows the ...
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TOTP, but share server time

Is there any major flaw in using TOTP in a way where the server sends its time to the client when the client requests to log in? The advantage of this is the client's time does not have to be set ...
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Is this a secure way of authenticating, advice on what to change?

I have a few terminals that I currently use a static IP to authenticate. The problem is in my country the internet is not stable, so often I have to switch to mobile data, then the terminals can't ...
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5 votes
1 answer
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Does TOTP make sense for verification codes?

I know that the concept of TOTP is for when the device on which the code is to be verified is separate from the device that is going to generate the code. However, I was wondering if it is a bad idea ...
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3 answers
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Why would a U2F key be more secured than an OTP device?

I have a Yubikey 5, I can store a PGP key inside, it has OTP abilities, FIDO, NFC, etc... Which is great for a device like this. First of all, I understand how a smart card is more secured than an app/...
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What are the security flaws in web based TOTP app?

If there is a widely accessible TOTP website (prototype: https://depperm.github.io/) that allows users to set a date and secret they can remember or a package that allows companies/developers to ...
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2 answers
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How is mailbox.org 2FA method referred to as, correctly?

Their 2FA to log in to their web interface requires two things: something you know (PIN); something you have (OTP, generated by app for example). After that, you need to log in by: input email ...
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5 votes
1 answer
554 views

Securely detecting and correcting time drift for TOTP

RFC 6238 recommends the server to implement some form of resynchronization algorithm to account for time drift of the device used to generate the OTP. However, the RFC provides very little information ...
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How does Authy implement multi-device mode?

This question has been asked previously, here. However, none of the answers there address the question. The accepted answer conflates Authy's multi-device mode with its cloud backup feature. I am ...
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Is 2FA required for one-time login links?

I'm currently implementing 2FA and ask our users that login with their email/pass to enter their code when 2FA is enabled. This is all good. But I also offer a "I forgot my password" access ...
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1 answer
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TOTP - Larger Timesteps

I'm in the process of implementing TOTP based on RFC6238. The RFC's recommend time step is 30 seconds. However, for addressing a resynchronization problem that we have, if I use a larger time step, ...
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3 votes
2 answers
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Why make it difficult to disable MFA tokens?

Some websites make it easy to enrol multiple TOTP apps at the same time but make it difficult to disable these apps. For instance, the user would have to completely reset the MFA settings instead of ...
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3 answers
259 views

prevent/prohibit duplication of MFA software-token / ensure user identity

As I was unable to find any thread about this particular question, I'm trying to ask the community for help. We're currently using RSA RADIUS based 2FA to authenticate external VPN users from ...
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1 vote
2 answers
212 views

In case of TOTP code generation, why do products prefer a generic authenticator apps, such as Google Authenticator?

All the products supporting TOTP-based 2FA use one of the common authenticator apps such as Google Authenticator, Authy, etc. I want to understand whether there are any security reasons behind why ...
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172 views

Combine HOTP and TOTP

I want to build a custom OTP implementation that utilizes the HOTP/TOTP algorithm. I need to create several codes (one time passwords), which are all valid for the same time window in the future (e.g....
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2 answers
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How do backup codes work in TOTP, like Google Authenticator?

My understanding is that in TOTPs are like HMAC where code is derived from time. However, I am struggling to understand the concept of Backup Codes in Google Authenticator, and how are they ...
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1 vote
1 answer
158 views

Is it unsecure to use TOTP codes on the device that generates them?

Let's say I have a TOTP generator app (like Google Authenticator) installed on my smartphone. I use it for 2FA for service X. How bad is it if I log in to X's website/dedicated app on the same ...
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How should I store TOTP recovery codes on the server end?

In TOTP implementations, it's always suggested that you give your users recovery codes. Should I treat these like tokens? Display them once and hash them? If so, I'd love to know why. If not, I'm ...
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3 votes
0 answers
289 views

One time password: combine time window and counter

I want to generate an OTP, that is valid once in a certain time window in the future. That time window is in the range of minutes to hours. After being used in that window, the OTP may not be used ...
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6 votes
3 answers
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Do backup codes render 2FA useless?

I've been trying to implement 2FA for a web application, both server and client side. As everybody knows, an H/TOTP is intended to prove that I own something, for example through the use of an ...
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2 answers
2k views

Is it safe to save a screenshot of my QR code?

For MFA I now use Authy (owned by Twilio) instead of Google Authenticator. I find Authy more convenient because it syncs your accounts between several devices and several authy installations which ...
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0 votes
1 answer
175 views

Securing shared key in TOTP Implementations

I'm currently learning about Time-based One-Time Password implementations (see RFC6283). I see that a shared secret is part of the algorithm. This shared secret is exposed to the user (see example ...
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2 votes
1 answer
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Are there security advantages to adding an OTP to SSH connections?

Are there any tangible improvements to gain from enabling TOTP (google-authenticator PAM plugin) over existing public key based SSH connections? Does it make security sense to enable TOTP based Two-...
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63 votes
2 answers
9k views

How are one-time password generators like Google Authenticator different from having two passwords?

Google Authenticator uses the TOTP algorithm to generate your One-Time Password (OTP). TOTP works like this : The server generates a secret key and shares with the client (you) when the client ...
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Risks of allowing an account to register multiple TOTPs

Is there any security risk for an application allowing a user to register multiple TOTP devices for a single account? I've noticed that with many popular accounts (gmail, github) you have the ability ...
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1 vote
1 answer
137 views

MFA for multiple accounts?

We are thinking about enabling 2FA with Google Authenficator for all our services. But the only concern for me now is that users will have to have a dedicated Authenticator's account for every ...
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4 votes
2 answers
1k views

Can a Time-based One-time Password (TOTP) key be decoded from generated values?

If you have access to generated Time-based One-time Password (TOTP) values, is it theoretically possible to decode the secret key? If yes, how much time and about how many generated values are needed?...
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2 answers
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How do I back up YubiKey-backed TOTP authentication?

I bought a YubiKey 5 NFC this week and have started using 2FA and U2F where I can but am deathly allergic to the idea of losing access. For backing up U2F access I'm going to buy a second U2F token (...
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0 votes
1 answer
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How does DUO push button method and other methods actually work?

Google authenticator uses HOTP and TOTP algorithm for TFA. What is the basic working principle of DUO push? What brings security to DUO push?
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Should I use TOTP when using OAuth2

I'm implementing TOTP in my application to allow users to use two factor authentication with Google authenticator and the like. However I've also implemented "social login" using OAuth, should the ...
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0 votes
0 answers
1k views

Two-factor authentication on Galaxy Watch - should secrets be encrypted, and is this SQLite example secure?

I recently got a Galaxy Watch and to get acquainted with developing apps for it I'm writing a simple two factor authenticator to generate TOTP codes from entered secrets using the Google Authenticator ...
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0 votes
1 answer
214 views

Are there security issues in not supporting TOTP 2FA for 1Password? [closed]

1Password sort of supports 2FA. We have a master password and an additional secret. But why don't they support TOTP for 2FA? I just want to make really sure that unless I approve, no other devices ...
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1 answer
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Risks of sharing multiple, old TOTP codes?

What are the risks (if any) of sharing the TOTP codes? I'm referring to the six-digit codes generated by Google Authenticator and the like. By "sharing old tokens" I'm thinking of posting online a ...
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3 votes
1 answer
575 views

Is it reasonable to store encrypted TOTP keys + authentication credentials on a single device (for end-user)?

My current security model (at least for passwords) is to store them encrypted at rest and use GPG (in combination with an Yubikey) to perform encryption / decryption. I'm using pass (https://www....
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10 votes
2 answers
2k views

Is it a bad idea to have the user choose the TOTP secret instead of generating it automatically?

Reading about TOTP-based authentication systems that use smartphones as one-time code generators, I seem to understand that typically the shared secret is generated automatically by the "server" (the ...
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3 votes
3 answers
4k views

What are dedicated TOTP devices called?

I would like to buy a device that can be provisioned with a secret seed and then displays a time based authentication token without ever revealing the seed. As terms like 2FA, TOTP and Authenticator ...
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30 votes
1 answer
11k views

Storing TOTP secret in database, plaintext or encrypted?

I've been reading about 2FA and how it is used, and the thing that struck me most is that everyone seems to be storing the TOTP secret as plaintext in their database. I understand you need the secret ...
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1 vote
2 answers
1k views

How can Authy use Google Authenticator QR

I was just reading around and found it really fascinating that Authy can use Google Authenticator implementations anywhere. How does Authy does this? Isn't this a security risk?
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1 vote
0 answers
355 views

How exactly do Fido Keys work? [closed]

Recently I acquired a security Fido key that allows me to use the U2F protocol on some of my accounts. Now I know that these keys use public/private keys for the specified account but I'm stuck on the ...
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3 votes
2 answers
813 views

Using the Symantec VIP Access smartphone software for 2FA

I'm most accustomed to using Google Authenticator / FreeOTP for my 2FA needs. This system allows me to have separate TOTP streams for each site and allows me to backup my seeds (by printing the QR ...
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0 votes
2 answers
6k views

Does the TOTP Algorithm rely on the client time always being synced correctly?

What happens if for some reason a cell phones clock / calendar is off by a significant amount of time? Does the TOTP (Time-based OTP) algorithm generate an invalid token? Also, do time zones play a ...
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4 votes
1 answer
210 views

Strong unique passwords and TOTP 2FA

So I use a password manager with to generate a (strong) unique password for each and every site I have a username / password for. For the ones that allow it I also enable TOTP (Time-based One-Time ...
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0 answers
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Does producing TOTP tokens weaken the stored secret? How much? [duplicate]

I am using Google Authenticator as a second factor on some sites, (including my Google Account). Every now and then I need to produce a token to log in. If some attacker received those tokens over ...
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