Questions tagged [one-time-password]

One-time password (OTP) protocols and implementations (software and hardware)

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1answer
46 views

How secure is to authorize a website to “trust your device”?

A bank has a form of 2FA where, after you put in your username and password, they send a code via SMS to your mobile phone and you have to put that too. On the screen asking for the SMS code, there ...
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0answers
45 views

What is the impact if there is Race Condition while submitting OTP?

I recently came across a web application where it was asking for an OTP after a successful login. Let the endpoint be https://www.example.com/otpcode The initial test for a brute-force of the OTP ...
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1answer
38 views

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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1answer
83 views

6 digit code to access the account?

All my security senses are tiggling when I wrote the title, but here's the scenario: When a user wants to connect to their account, but can't remember their password, they can use the "Lost ...
2
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1answer
85 views

Why don't OTPs have letters?

Is there a reason why OTPs (one-time passwords) are only made up of numbers? I've seen OTPs of varying lengths but all of them are only made up of numbers. Why are they not alphanumeric?
5
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1answer
192 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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7answers
6k views

Don't one-time recovery codes for 2FA introduce a backdoor?

Although using multi-factor authentication is clearly a good move, I'm struggling with the 'one-time recovery codes' concept. It seems to me that if you choose to use them, what you're doing is ...
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0answers
39 views

Can OTP (One-Time password) be used to protect data after intrusion has been detected? [closed]

I am working on Social Engineering attacks happening via SMSs. Let's assume a person receives an SMS asking him to click on a malicious link. If a virus is installed on the person's device, how can ...
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1answer
99 views

How should I share a TOTP shared key with my users?

I want to add one-time passwords as gates for certain important actions in the application I am working on. It is not two-factor authentication, although it may be extended to that use case later. ...
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2answers
248 views

Magic links: JWT vs random string

Tutorials I've come across about implementing magic link authentication (in Node) recommend a mechanism like this: the user hits your endpoint with their email address you generate a signed JWT from ...
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2answers
87 views

Protecting OTP based authentication

Let's say I have a website which uses 4 digit OTP based authentication for login i.e. users will enter their mobile number, receive OTP on the entered mobile number, enter the received OTP to login ...
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0answers
129 views

In forgotten password is asking user their TOTP among other details secure?

I have started to work on the Forgotten password feature on my website. Based on OWASP Forgot Password cheatsheet, the user should provide enough information to confirm that it is really them. The ...
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32 views

Handling parallel login and Max invalid attempts using OTP with same phone number

I am designing a login system that performs login operation using OTP and Email ID of the registered user. The current approach is as below User enters the Registered Email Id If the Email ID is ...
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1answer
114 views

Is phone number verifications with SMS magic HTTP links less secure than OTP?

I want to verify phone number ownership with specially crafted and encrypted payload within an HTTP hyperlink callback through SMS as opposed to sending an SMS OTP code and writing it back in server ...
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6answers
6k views

Is revealing the phone number during OTP verification process considered a vulnerability?

One of the common way of implementing 2FA is using phone number Text message or Call with OTP. As I can see, usually web services show something like: OTP was sent to the number +*********34 Is it ...
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2answers
117 views

Best practice for authenticating resend email requests

I have a Node.js/Express 4/JWT user authentication service using Passport.js, with Sequelize and MySQL for database. In my service, upon signing up/resetting a password, the user will be redirected to ...
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1answer
80 views

Password protected wall

I'm currently building a website where you have an account and can do "dangerous" things with it. I want to password-protect these things, so the user has to type their password, if they ...
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0answers
689 views

How is a bad actor able to disable Amazon's 2-step verification without supplying a OTP?

My wife's Amazon account was hacked yesterday. She discovered the purchases, changed her password to both gmail and Amazon, and enabled Amazon's 2-step verification (2FA) through SMS on her phone and ...
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1answer
154 views

What could be the reasons for two different OTP messages for the same merchant when we do online transactions through debit card?

While I was doing a transaction (say adding money to one of the mobile wallets) through a SBI debit card, I could see two different OTP messages for different transactions. (Please refer to the image) ...
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2answers
101 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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0answers
539 views

Why my mobile sends SMS to a random number without my permission?

My mobile sends SMS to random numbers without my permission. All messages are sent automatically. Here is an example of an SMS. SBIUPI qUrXgeX26iEY%2B2si9JHhubIjm7R2aHoo6pWcbXBpJho%3D All the ...
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2answers
190 views

Is an OTP alone useful for a hacker?

Further, does an unused OTP expire by itself? i.e in regards to digital banking - in case a hacker accesses your SMS's through malware or other means.
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1answer
116 views

A proposal for effortless two-factor authentication

I have an idea for device-level two-factor authentication that involves no direct input from the user, and I wanted to find out if something like it has been tried before. Let's say I have an account ...
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1answer
377 views

How to use Yubikey 5 NFC for online accounts, Linux login, and KeePassXC?

I just got my Yubikey 5 NFC, and would like to use it for Linux desktop login Linux KeePassXC (which only supports hmac-sha1 challenge-response) online accounts When reading about U2F it seams to be ...
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0answers
78 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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2answers
266 views

Password reset link vs Temporary password

Which is harder to exploit: Password reset link with tokens/timestamps/code/ticket etc Or, temporary password sent on user mail using which login can be done and password can be changed. Any ...
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3answers
4k views

Am I generating email link tokens correctly?

I am developing a reliable system for token generation and validation used mainly for links in confirmation emails (reset password request, change email flow, activate an account, etc...). There are ...
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2answers
740 views

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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2answers
134 views

2FA: Do app passwords render the second factor invalid?

I am currently in the process of employing a 2FA authentication on as many services as I can. If it is relevant for the question: I use a time-based OTP authenticator app. When setting up, I noticed ...
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0answers
46 views

Why have a password at all? [duplicate]

Consider the following common security scenario: I need to log in with an email and password. I can't remember my password so I click "forgot password" Website emails me a password reset link. I can ...
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2answers
130 views

How does password-append OTP validation work?

Recently when I was changing some Amazon account settings, I've noticed that they provide an option to validate the OTP by appending it to the password. How would this work, if the password is one-way ...
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1answer
73 views

Is it unsecured 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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1answer
754 views

Is there a reason to change OTP code on every resend attempt?

This question is about OTP codes that are used in flows like Email verification SMS 2fa Usually, when you send an OTP, you want to give the user an option to resend the OTP. Assuming the following ...
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2answers
484 views

How to encrypt data with a one time password?

We can generate OTP using HOTP - RFC 4226 and TOTP - RFC 6238. But the generated OTP normally has a checking function authenticator.check(token, secret);. But this only checks if the OTP is valid. ...
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2answers
417 views

one-time link on 1ty.me

1ty.me is a website that allows you to send secret messages (password, nuclear code, etc.) to someone with a one-time link. So when someone receives the link and clicks on it, the secret message is ...
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0answers
150 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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1answer
1k views

Is it possible to bypass 2FA and access bank account in this system?

Nowadays, any credit/debit card transaction made online (at least for mine) requires one to enter the card details (Account No., Expiry Date, CVV etc). In the end, a OTP (One Time Pass) is sent to the ...
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1answer
398 views

Can 2FA / MFA be secure & functional in a purely offline state (PWA)?

I'm building a Progressive Web App intended to be used primarily in an offline state. The user can "login" while disconnected, which verifies the password against a locally-stored hash and some other ...
3
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1answer
81 views

Protect page sms verification from spamming

I'm developing a merchant page where users can pay their bills. On this page, users must fill in their bank details (Card number, card holder name, expiration date, CVC). As a verification, we have a ...
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0answers
172 views

Is there any Password Manager that supports Hardware-Based OTP encryption/decryption?

I see that some projects like KeepassXC use CR based OTP to provide some additional security. While this is discussed quite controversial my opinion is that - for quite some cases (e.g. most non-...
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5answers
8k views

Why do many websites hide input when entering an OTP?

I've noticed that on many sites, when they ask for a one-time password (OTP) (usually sent by SMS), the input is hidden in the same way as a password field is. My understanding is that once an OTP is ...
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2answers
729 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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2answers
647 views

When resetting a password using OTPs, how can I prevent users from bypassing the OTP input page?

I am implementing the password reset functionality using OTPs (one-time passwords). When the user clicks on the 'forgot password' link, he / she is sent an OTP and is redirected to the OTP input page. ...
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4answers
22k views

Bypass with wrong cvv of debit card and getting OTP

This is happening in Visa/MasterCard/American Express, etc. I tried checking in many payment apps and payment gateways that if I enter the correct debit card number, name, valid date, and wrong CVV ...
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1answer
176 views

What point in Authenticator App 2FA when SMS fallback is enabled

I would like to move away from SMS 2FA (because of Should 2FA over SMS be considered insecure in the wake of recent SS7 attacks? for example). But some services that provide Authenticator apps ...
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0answers
835 views

Persistent OTP on Web Browser using cookie

Currently I'm planning to use OTP for my web app, I'm a bit confused about how to keep the users logged on the app. My plan is to use cookies, but I'm not sure whether this is correct or not. This is ...
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1answer
119 views

Am I making my One-Time Passcode less secure?

I am using some "magic link" one-time passcodes for automatically logging users in for a specific purpose on our website. My plan is to generate a hash based on the datetime, users specific "ID" and ...
0
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1answer
92 views

What will be the problems if 2 users receive the same OTP in an arbitrary time gap?

First of all, I sincerely apologise if this question has already been asked before. I searched in Google and on this website but was unable to find any article. I have seen that most OTPs are 6 ...
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0answers
118 views

Storing TOTP codes on a Feiteian ePass FIDO key

I'm looking for some Android apps that can store / read TOTP codes off of a Feitian ePass FIDO key using NFC. There appears to be a fairly simple way with a yubico key / and key but I don't know how ...
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2answers
5k views

Which is more secure Yubikey + Keepass using Challenge/Response or Yubikey + Keepass using OTP?

I use a Windows 10 PC and an Android phone with Keepass. I would like to add a second factor on top of my master password that works with both Windows 10 and my Android phone. Between the two ...

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