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

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Generation of a shared nonce that cannot be pre computed [on hold]

Is there any system out there currently, which can generate a nonce, which all nodes on a distributed network can agree and calculate the same nonce at the same time, but one an attacker cannot pre ...
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1answer
15 views

How big window is secure and practical with TOTP?

We are using Time-based One-time Password Algorithm (Google Authenticator) in our system. Since we currently don't allow any time window and code validity is just 30 seconds, we are constantly having ...
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2answers
64 views

What is a good way to generate a one time pad, and is this a good way? [duplicate]

Is there a good/better/best way to generate a one time pad? I would like to only utilize about 40 characters (a-z, 0-9, .,!-). What I have come up with is perhaps not the BEST way, but seems to fill ...
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2answers
35 views

Is email OTP improving the security for 2 phase authentication?

There has been similar questions before where people say that using some other means (sms, hardware devices, etc.) is a more secure way to provide 2 factor authentication. Provided we don't have an ...
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0answers
75 views

How is PasswordSafe different from KeePass/OtpKeyProv?

Over at Does adding two-factor authentication by OTP really make KeePass more secure the top answer unmistakably states that KeePass is not made more secure by using an OTP. I told a friend I was ...
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108 views

Password Reset URL forwarding

If a previously registered user clicks on the password reset button during login, I want to send them an email with a reset password link. I have three queries: How to add an expiry date to the ...
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2answers
156 views

What happens if a (google authenticator) one time password QR code is leaked?

When there are QR codes for one time password (OTPs) urls (starting with otpauth://) that are supposed to be looked up in an authenticator app such as Google authenticator, what happens if a user ...
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1answer
72 views

Using the password, among other values, as key data in two-factor authentication

I'm writing an implementation and a thesis about two-factor authentication, and am currently doing some research. I'm currently looking at an implementation for deterministically generating a ...
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1answer
74 views

OTP on the same device being used to login

I've seen mobile apps use two factor authentication by sending an SMS to the mobile phone. However, if I've stolen someone's phone, where is the security advantage? I can understand it if it's used in ...
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54 views

Why are there no “disconnected” OTPs on mobile handsets?

I have seen: RSA SecurID hardware tokens which require no mobile networks, but need specialized devices mobile OTPs that need mobile networks and work on devices we carry frequently Hardware ...
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2answers
118 views

TOTP Resynchronisation

Considering hardware tokens implementing OATH TOTP (c.f. RFC6238), it is common knowledge that the clock in such tokens drift. A token that is not used very often is likely to drift way beyond the ...
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147 views

Email for the second factor in 2FA systems

the scenario is in a corporate environment and not connected to internet. The other day I was arguing with my colleague on whether email is good enough to be the second factor in a 2FA system. My ...
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96 views

Signup/Signin with Mobile+PIN

Telegram implements signup/signin with mobile number and a 5-digit one-time password. I believe the flow to be something along the lines of this: Grab the mobile number, generate an OTP, cache it ...
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55 views

Time Based Authentication

I need a way of authenticating that a file was generated by a particular machine that has a unique ID and a unique random secret also known to the authenticator, as an added difficulty the file ...
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1answer
110 views

One time password question

Suppose F(X) = (5X) mod 9 is used to generate a one time password. I am supposed to generate the first 8 values using the above formula, starting with the seed value of F(5) Well I know that F(5) = ...
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1answer
139 views

Lamport OTP system

This might be a stupid question but forgive me. Is the Lamport OTP algorithm different from HOTP and TOTP? How similar or different are they? Thanks in advance
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1answer
84 views

What happens when authenticating through a phishing attack with FIDO U2F tokens

So I have looked around and haven't found this anywhere. What happens when the response server is a phishing site with FIDO U2F tokens? Basically, if login just fails, I would assume that the user ...
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4answers
163 views

Are there any two way + two factor authentication systems in use?

My bank, Google etc. use two factor systems where they send me a One Time Password via out of band means. e.g. SMS or an App on my Cellphone or a standalone RSA token generator. This seems good ...
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1answer
103 views

Using Google Authenticator for SSH sessions

So I have an SSH tunnel which I use with dynamic port forwarding to the alternate http port on the client. For initializing this connection, I'd like to implement an additional verification step, ...
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0answers
130 views

Generate secure one-time codes containing information

I need to create a system that allows a user to enter codes to charge an allowance. Embedded in this code should be the amount to charge the allowance. The user would pay for a code which would then ...
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1answer
809 views

Why is the truncate function for HMAC one time passwords so complicated?

I've been reading through RFC4226 as part of some research and I was wondering why the function to truncate the HMAC was so complicated. As far as I understand it, the last 4 bits of the HMAC define ...
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4answers
1k views

One Time Password via Text Message: Possible exploits?

Is there a credible scenario in which the OTP (One Time Password) for online credit card transactions ( specifically for Verified by Visa) can be bypassed? Context: A guy I know was cheated via the ...
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105 views

Store 2-legged one-time password's key securely

I have a system with a OTP authentication and I need a method to encrypt the main "secret algorithm". In my system each OTP has a pair named "solution" and it is also changing like the OTP. I need to ...
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1answer
63 views

Implement GPG Verification (Bitcoin-OTC)

I'm looking to implement a "Verify with Bitcoin-OTC" feature for my web app. The general idea is the user would prove he owns a particular account on the external site Bitcoin-OTC and my app would ...
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1answer
142 views

Secure copy-paste from phone to computer

Some computers on my university block the keepass application which I use as a password manager. I'm thinking of building a small web application + Android app which lets me securely copy a string ...
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323 views

How secure is a password app that stores both the password and two factor secret in one place?

Take for example 1Password, that now can store your password and one time password secret in a single place (your 1Password vault). I know it isn't truly two-factor anymore, but how much better is it ...
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61 views

When, during authentication, should I ask for an OTP token?

I was working on implementing an OTP strategy in our login process of a web application when I was asking myself: Should I ask for the OTP token before or after asking for the username/password? What ...
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158 views

Usability of a found OTP Token for my own system [closed]

I found a one-time-password token and am unable to find out who it belongs to or where it has been used. It seems to be manufactured by a company called "ActivIdentity" (now "HID") and called the ...
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3answers
235 views

How to integrate AAA and otp

We have AAA services enabled in our organization (about 1000 clients). We want also to add otp (one time password) service. What are the main security concerns about integrating them. Is there any ...
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33 views

Double step verification system for homepage

I want to share some of my work with some double step verification system. PGP is not enough, since some of my clients cannot use it. First, you need a password to login but you also need the code ...
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3answers
245 views

Should LastPass use the YubiKey public identifier as a secret key?

I've just picked up a YubiKey. However, the demo Yubico redirect you to is served over plain HTTP, over which each OTP you generate during the demo is POSTed, enabling you to verify that your key is ...
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1answer
414 views

Best practices for usefully storing two factor authentication backup codes?

For a lot of web services offering two factor authentication, after setting up the system, you are given a short list of backup codes (one-time pads) that are around 7-10 characters long. These are ...
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99 views

Algorithms for transaction authentication

It's unclear to me how transaction signing and transaction authentication work. Industrial solutions use both symmetric and asymmetric algorithms to compute the signature. What does RSA add the ...
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HMAC-SHA256 Transaction signing [closed]

Can rfc6238 be used for transaction signing by concatenating the random seed string with transaction details (such as amount and target account number) ? Could a transaction authorization 8-cipher OTP ...
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133 views

find out the algorithm based on some examples?

I have an OTP generator that receive two numbers less than 99 as input and return an 8 digit number as its output. I know it has a simple algorithm. because its processor is just an ATMEGA8 micro ...
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143 views

How to cryptoanalyze a one time pad that uses a plain text document as the pad?

I have read that in order for a one time pad to be truly secure, the pad itself must be random data. Given the practical difficulty of sharing a secure random pad, I was wondering what would be the ...
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1answer
2k views

What are the differences between the U2F and UAF FIDO authentication standards?

Google recently announced support for Universal 2nd Factor (U2F) authentication in Chrome and started allowing that authentication mechanism to be used for 2-factor authentication across their various ...
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6answers
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How secure are the FIDO U2F tokens

Google and Yubico just announced the availability of cryptographic security tokens following the FIDO U2F specification. Is this just another 2FA option, or is this significantly better than solutions ...
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64 views

Can OTP 2FA be reversibly determined?

Please note: I'm not necessarily talking about what happens when one shoulder surfs someone inputting a OTP. I'm fairly confident that it's nearly impossible (or extremely impractical) to guess the ...
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4answers
925 views

One-Time-Passwords resist against bruteforce attacks? Immune Alternative?

Does a One-Time-Password like Google Authenticator or YubiKey protect against brute force attacks with unlimited computer power? If not, what algorithems are immune to bruteforce attacks against ...
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184 views

Verification code generation and expiration

I am trying to implement an application that includes registration, In order to register to the system the user shall enter his organization ID number let's say. To verify the user identity, a ...
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359 views

Idea for an algorithm to authenticate users with zero-knowledge-proof [need thoughts/review]

I have an idea for an algorithm. I don't know if I made any mistakes and need some extra thoughts/peer review on it. This would work as an (almost)zero knowledge proof for sending passwords that can ...
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1answer
451 views

What are the typical ways to generate a One Time Password?

I'm looking for the typical ways to generate a One Time Password. I know about the HOTP and TOPT. But, in my case, the problem is that the "server" only has a display as interface and the ...
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3answers
3k views

Is it possible to use one-time passwords for WI-FI?

Is it possible to configure an access point to use one-time passwords for authentication and encryption ?
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106 views

OTP for syncing mobile device

Scenario: a web app with two-factor authentication using username/password and hardware OTP. Once logged into the app, one of the app modules should be used in a tablet or any mobile device without a ...
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4answers
282 views

Why must every OTP be unique

All OTP systems that I have observed, send a new OTP every time a user requests for an OTP. (for example whatsapp) Only the latest OTP is valid and an OTP can only be used for X hours. I am wondering ...
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2answers
141 views

Are there any flaws in my design for a paper-based OTP grid?

I'm trying to implement two-factor authentication on the cheap for a website of mine. My bank uses this sort of grid-based OTP system, so I wanted to emulate it in my application: Cards are ...
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3answers
356 views

Where is the TOTP secret key stored on client applications?

I'm new to concept of TOTP, but as I understand, 16-character base32-encoded shared secret is stored in the client application(for example Authy, FreeOTP)? This means that if I remove the application, ...
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203 views

Google Authenticator Error on Reboot

I have set up an SSH server to accept only login using codes generated by Google Authenticator (I have disabled all other forms of authentication on that port). After having rebooted my remote ...
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180 views

Algorithm to Transaction Data Signing

Transaction Data Signing I need an idea to develop a very secure algorithm to authenticate online operations using PHP in the server and an Android app in the user's device. What is the idea? The ...