Questions tagged [authentication]

Authentication is successfully validating that an entity you are communicating with is actually who they claim to be. The entity typically demonstrates who they are by showing they possess a secret that only they could know.

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Are key files good authentication?

Let's say $p$ is the pool of files in a folder. And $k$ is the files in the pool that are "key files" for authenticating in a service. Note: The order of the key files matter. Then we have $c$ which ...
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Two-party symmetric key establishment protocol

I need a symmetric key protocol that will mutually authenticate and establish a new short-living session key between two parties that have a pre-shared key. Unfortunately, I have not found any ...
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How to encrypt numeric data on a ticket

I have a customer with an existing ticketing system that generates tickets for events like theaters, movies, football and so on. The information in each ticket is encoded in a 16 decimal digit ...
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960 views

What is the difference between static and dynamic tokens?

First, what is the difference between hardware and software tokens? Tokens are "what you have" for example a car key or a chipcard. This would be (I think) hardware tokens? But what are software ...
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Password Derived Signature Authentication

I'd like to avoid sending user passwords over the wire. Would the following challenge response protocol be secure (served over TLS)? I know this is similar to SRP. Sign-up Client takes password and ...
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Authentication without decrypting the password?

To my knowledge it works like this: The server receives the username-password values over a secure & encrypted channel. The username-password values are decrypted in the server and are present as ...
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Most energy-efficient authentication protocol?

I am looking for a cryptographic protocol that is as energy-efficient as possible. I am talking about battery drain. Alice wants to do a mutual authentication with Bob. Maybe symmetric is good, maybe ...
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259 views

Is my method of identifying remote ZMQ clients secure?

ZMQ provides a CURVE based authorization / encryption system based on certs/keys. After endpoints are authenticated to the server, they can send an "identity" with each request. Unfortunately they ...
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Could you design something like a ring signature that uses website accounts instead of keys?

Ring signatures allow one to prove that you own a private key corresponding to a public key from a set of keys, without revealing which private key you control. This is useful if you are part of some ...
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602 views

Fiat-Shamir zero knowledge protocol

In Fiat-Shamir protocol, the final calculation is $$y^2=x\,v^c$$ Where $c$ is the random $\{1,0\}$, $x$ is the witness and $v$ is the public key $s^2 \bmod n$. My questions are: What stops the ...
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Message authentication vs entity authentication

Does message authentication authenticate the entity? If the answer is "No", because message authentications like MAC work with the shared symmetric key, then my second question is: Does a message ...
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Definition of Short Authentication String

I am studying for my cryptography final and I passed by the following term: short authentication string. Please, can anyone explain it to me, thank you very much.
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What is the use of SCRAM-SHA-256 (over SCRAM-SHA-1)?

The Salted Challenge Response Authentication Mechanism (SCRAM) specified in RFC 5802 can use arbitrary hash functions to operate. The base version from RFC 5802 uses SHA-1. From my understanding, ...
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135 views

Two-way secret sharing for authentication?

Secret sharing, using methods such as Shamir's Secret Sharing allows for t out of n shares to recreate a secret. For authentication, the secret can be a user ID. A client with a logged-in user can ...
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Can “OPAQUE-over-TLS” authentication be optimized?

So while discussing the issues of password-hashing off-loading in our chat I noticed that it's easy to extend OPAQUE (CFRG draft) to essentially be a better standard password based authentication when ...
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Disadvantage of the using a counter within plain text for encrypting with AES256 and authentication?

What if we use a counter within the plain text and then encrypt the plain text with aes 256 to encrypt & authenticate? For example: encryptAES(32bit_counter+plain_text_of_96bit); or encryptAES(...
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Is this device authentication method (using AES-256) secure?

Let's say we have: client_id_ran: 256 bit random text (chosen only once for whole system) used to generate client_id by ...
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Security of three-pass mutual authentication under ISO/IEC 9798-2

Based on 5.2.2 of the international standard ISO/IEC 9798-2 (http://bcc.portal.gov.bd/sites/default/files/files/bcc.portal.gov.bd/page/adeaf3e5_cc55_4222_8767_f26bcaec3f70/ISO_IEC_9798-2.pdf) Why ...
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327 views

Are SSH key-pairs an example of a zero knowledge proof?

Quoting from source, authentication using SSH key pairs goes something like this: 1) The client begins by sending an ID for the key pair it would like to authenticate with to the server. 2) ...
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487 views

How does the user get the private/public key with HMAC based request signing?

I need to implement a HMAC signing of requests and I have read this article which explains the basics of what it is and how to achieve on theory. https://blog.andrewhoang.me/how-api-request-signing-...
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What would happen if the last message in a three-pass authentication protocol was undelivered?

I did read some articles about the protocol but couldn't figure out what would happen. Would the two parties be unable to verify each other? Or would it be something else? based on the international ...
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Authentication protocol for communication with Arduino Uno

I am using an ECDH key exchange to establish a shared secret between an Arduino Uno and an Android device. For this purpose I am using this library and more specifically Curve25519. This is the ...
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Can a Message Authenticaty Code recover original data from corrupted data?

I am new to cryptography and have been studying for Dan Boneh's Stanford Course on Coursera, after going through encrytpion and decryption I've started the integrity portion of the Course. Sir ...
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Cryptography scheme to prove you really are the author for something

Say I'm a researcher like Satoshi Nakamoto that wants to stay anonymous. I want to publish documents and sign them somehow. A few years, I want to reveal my identity and prove it was me who was ...
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JWT Login Security

I am new to security and I am wondering if JWT is secure enough. From what I have read online the flow goes like this: Clients log in by sending their credentials to the identity provider. The ...
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Asymmetrical encryption with multiple sufficient key-pairs [duplicate]

I have the following requirement: There are N public/private RSA key pairs. The encrypted data must be decryptable by any of the private keys alone, but not by any other key. For encryption, the ...
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How to calculate a multiple-character checksum for authentication using a tabula recta?

I am not sure if this is possible to do using a tabula recta, but I would like to know how to calculate a multiple-character checksum of a text. For a single-character checksum, it's easy. You just ...
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Login security and plaintext of a password stored in Argon2i to derive a key via halite safe?

I'm using Symfony 4. I have set parameters on all my Argon2 stuff below so that it takes 1s per iteration. This website is supposed to encrypt HIPAA information. Basically I have a table like this <...
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258 views

How is ZKPP better than signing nonces?

I am trying to understand the use case for zero knowledge password proofs. Clearly, it is not ideal for a remote server to store a password hash. Then I need to upload the password to the server for ...
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770 views

How to generate tokens from a secret key?

The problem is simple: I want to be able to spit out 256-bit "tokens" that only I could've produced because I know my secret key $s$, and given any number of these tokens, no one can figure what $s$ ...
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Drawbacks of Schnorr Authentication that require Fiat-Shamir and Random Oracles?

I've been going through G. Maxwell's paper on the Borromean Ring Signature, and I don't fully understand this part on Schnorr Signature. If some could explain it more intuitively thank you. "...
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How does EAP-TLS authenticate?

I understand that a client and server certificate is required, however the validation process isn't clear to me. Is it simply that the certificates are check to ensure they're valid, aren't revoked, ...
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287 views

Where should I start to learn cryptography? [duplicate]

I want to learn cryptography. I just wanted to ask people who are experienced about the field where I should start. Any recommendation would be something for me. Thank you in advance.
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Cost of asymmetric signature checks vs password hashing

This is a question about standard every day web authentication. I have the following assumptions: one of the reasons public key user authentication is not used as bread and butter on the web is that ...
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338 views

Is using a smart card and password two-factor authentication?

I use a smart card - as read only device - for user identity as well as a password: The smart card (holds the user ID) is something I have; The password is something I know. Is this still two-factor ...
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Using a blockchain for secure communication

I've recently heard of the idea of using a blockchain for secure communication. No details were given so it's a little hard for me to say that it can't be done. But as far as I know: Secure ...
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Is timing attack practical in a web developer's perspective?

Let's say my server has a non-constant-time compare function for checking if the visitor has a valid session id. The time it takes for the comparator to run would be very insignificant, usually within ...
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CCM authenticity bound

Can someone help me understanding the CCM authenticity bound by Phillip Rogaway? i-e Success probability < $q_{\text{dec}}/2^\tau + \sigma/2^b$. $\tau$ is tag length, where as $b$ is block length. ...
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255 views

Authentication scheme using HMAC

I have an authentication service, a client and an application service. The client needs to use the application, but they have to be authenticated first. I'm trying to create a simple scheme to do ...
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Using nested signatures to trust public key of inner signatures

I have a scenario where entity $A$ has an unauthentic copy of the public key $P_B$ of $B$ and an authentic copy of $P_C$ of $C$, trusted by both $A$ and $B$. Now $A$ wants to establish trust in $P_B$...
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Client-side password stretching - danger of the salt being public?

In case of using client-side password stretching (plus a single hash on the server) - the server would need to send the salt before authentication, of course. Though the salt is not considered a real ...
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passive corruption ?= Byzantine corruption in the UC framework?

Notations: We follow the convention in the UC framework. We use $\mathcal{A}$ to denote the adversary, $\mathcal{P}$ to denote a party in the model. We focus on two types of corruption in the UC ...
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Authentication and integrity

I was trying to solve this problem: Sometimes Alice needs to send a file to Bob, guaranteeing her identity and the file integrity (no confidentiality required); the two parties are sharing a secret w ...
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What is the point of using a cryptographic sequence number if you're not using it as a nonce?

OSPF features the use of Auth Crypto Sequence Number however, from reading the RFC it would appear the sequence number is not being used as a nonce. In addition, ...
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Generating secure short activation code for offline applications

My application is as follows User has a hardware system (with an unique ID) that does not have connectivity but has a keypad for input. To make the hardware operational, the user has to go to central ...
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162 views

shared symmetric key

Suppose $R$ is a random challenge sent in the clear from Alice to Bob and $K$ is a symmetric key known only to Alice and Bob. Which of the following are secure session keys and which are not? Justify ...
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Attack on challenge response protocol using shared symmetric key and addition of random nonce [closed]

Consider the following mutual authentication protocol, where KAB is a shared symmetric key. Give two different attacks that Trudy can use to convince Bob that she is Alice.
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What can I do, if my SRP password verifier was stolen?

I've got a system that works like this: ...
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693 views

Password vs public key for authentication?

What's the difference password and key in terms of authentication? I think that they are potentially same. But, in practice, password involves some bias since it is created by human. On the other ...
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267 views

Encrypted Hash vs MAC [duplicate]

I (believe I) am aware of the general difference between a hash and a MAC; the former is used for integrity and the latter for integrity and authentication as it also takes a secret key as an input in ...

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