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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CBC-MAC with length appended not UF-CMA secure followup

I know that CBC-MAC is not UF-CMA secure if the domain contains message of arbitrary length. Read from this post But what if we append the length of the message when run the MAC algorithm. (to MAC ...
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Forge valid token with misuse of OTP key reuse

I'm new to OTP and received a challenge. Challenge Context: A server uses OTP to encrypt and decrypt authentication tokens. Misuse: The server always uses the same key. Objective: Forge a valid token ...
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Can a client with an ECC certificate and a server with RSA certificate establish a mTLS connection? [migrated]

Can a client with an ECC certificate and a server with RSA certificate establish a mTLS connection? Can they agree on a cipher suite? Why?
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Smallest possible certificate for IoT device

I'm developing an IoT system that uses small nodes connected through RF. This allows messages under 250 bytes long. You can check it at https://github.com/gmag11/EnigmaIOT. All messages are encrypted ...
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Forgery attack on Poly1305 when the key and nonce reused

Introduction: I've tried to find how reusing one-time key compromises itself but only found information that it breaks the encryption entirely, it is written everywhere. But since no methods to reuse ...
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Is fingerprint authentication meaningless if the server/client is closed source?

I'm talking about when two chat users want to verify their identities via public key fingerprints. If the Client app is closed source, and we cannot see what it is doing, isn't the Server able to play ...
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Choose Argon2i or Argon2id for secure password hashing on a website? [duplicate]

I make a website with authentication. I have studied a lot of answers to these questions, but I still don't understand what is better and safer to use for a website: Argon2i or Argon2id? I know which ...
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59 views

MitM with regard to unauthenticated clients

I'm trying to understand how man-in-the-middle attacks are prevented during key exchanges, and am confused by this Wikipedia statement: Use of mutual authentication, in which both the server and the ...
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“letter and key” security?

I'm sure there's a proper name for this, but I have no idea what it is. When my family fled Europe, one of the remaining items are a letter and a key from a bank. The general idea was that whomever ...
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45 views

HMAC for hash list

If I have a very large input to hash with a hash function vulnerable to length extention and I am using a hash list, should I HMAC each part of the input or just HMAC the final hash of all the hashes ?...
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Difference Between an Authentication Token and an OTP (One Time Password)

I would like to better understand why some people use the term One Time Password and other Authentication Token. I have noticed that in academic circles, there is a differentiation between ...
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Why is this authenticated Diffie–Hellman key exchange insecure?

I was searching for the information on authenticated Diffie–Hellman key exchange and found these slides. The author says, “Remember $$A\to B: (A, g^x, \operatorname{SIG}_a((g^x, B)))$$ $$B\to A: (B, g^...
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Can we say that password authentication contains registration phase, authentication phase and authenticated key exchange phase?

Authentication aims to validate the legitimate identity. The authenticated key exchange aims to establish a secure common session key. But can we say that password authentication scheme contains the ...
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Could PAKE via smooth projective hash function protect agaist replay attacks?

I came across some password-based authenticated key exchange (PAKE) protocols that are based on the smooth projective hash function (SPHF) in the standard model. And I checked some related works, and ...
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Isogeny-based AKE: what is the difference between Gal 1 and FTTY 1?

What is the difference between (a) the AKE scheme proposed by Galbraith (based on TS2 protocol) in https://eprint.iacr.org/2018/266.pdf (page 9-10); and (b) the AKE scheme proposed by Fujioka et al. ...
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How does CL signature work?

I'm studying the CL signature that how can it works. However, I cannot understand how equation (42) is calculated. What is the last three factors? The value T is as follows: $$T \leftarrow(A')^{\...
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Prior art: SSH key authn over TLS?

I’m developing an application that runs over TLS. In addition to password-based authentication we’d like to be able to use SSH keys. Is there any prior art in using SSH keys for authentication over ...
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OAuth(2) and friends

I've worked on low-level security (side-channel attacks etc.) for years and have a PhD in crypto. Web security is something I've never needed to touch beyond knowing how the TLS handshake works with ...
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How do NTLMv2 hashed passwords work?

We have an application which embeds NTLMv2 password hashes into its configuration. In attempting to assess the security of this practice, I'm not finding much straightforward information about how an ...
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Authentication using a nonce

For an authentication problem imagine the following scenario with two devices: 1 server 1 client. The client starts a conversation with the server and sends him his public key. All public keys in ...
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Possible issues with ECIES using a static (non-ephemeral) sender key

After looking at this bitcoin-related ECIES repo I believe the intention is that, at least in some cases, the recipient would know that the message is intended for them and use an secp256k1 public key ...
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Integrity for mixture of encrypted/unencrypted database fields

I have multiple blobs each (symmetrically) encrypted with its own randomly generated key. Now I want to encrypt these blob keys with user keys and store them in a database. A table could have the ...
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Is MAC process different for symmetric and asymmetric?

Message Authentication Code as far as I know works on the shared secret key. Do they work in the same way. Is there no difference between symmetric and asymmetric processes. Can anyone please explain ...
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47 views

Secure password reset

In my model I use two different keys, one for authentication and the other for the encryption / decryption of the data that the user saves, each derived from the master password with a KDF function. ...
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How much entropy do I need to add to passwords if they are NOT used in conjunction with logins

I'm building a system to authenticate users to a website via a single use login token. This token can either be included in links OR typed in directly by the user as a code. Because of that second ...
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KDF and salt storage

Regardless of the KDF I will use, let's imagine that I have to generate two keys, one for authentication and the other for encryption (which will always remain on the device that generates it until ...
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Diffie-Hellman man-in-the-middle attack

Diffie-Hellman Key Exchange Basic Protocol: Let G be a cyclic group of order $n$ and generator $g$. Alice chooses $a \in \{0,\ldots,n-1\}$ and Bob chooses $b \in \{0,\ldots,n-1\}$. ...
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What is the definition of dummy password?

Recently, I try to read some papers about Password Authenticated Key Exchange (PAKE). I can’t understand the meaning of “dummy password .” Can someone gives a concrete definition of it. And what is ...
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Check device authenticity by HASH

Hello I'm working in a school project and I'm trying to resolve an issue. I have a server, a BLE device and a computer. The BLE device is constantly advertising data, I'm using 7bytes of the data ...
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Using EAP-TLS with devices managed via Meraki/InTune

I have a question regarding the use of EAP-TLS with Meraki (iOS) and InTune (Windows). I've checked and both support EAP-TLS, among other authentication methods. I'd prefer this one as I want the ...
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If I want Integrity and Authentication AND Non-Repudiation, can the Digital Signature be based on the MAC?

Let's say I'm making a digital signature like this: hash = hash(message) digital signature = encrypt_with_private_key(hash) where the private key is Alice's ...
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Bluetooth: Why is the Secure Simple Pairing protocol asymmetric?

I'm reading the Bluetooth specification (version 4.2) and feel like I'm missing something. The Authentication Stage 1, using the numeric comparison protocol is described in Vol 2, Part H, Section 7.2....
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Using encryption for authenticating messages (instead of signing)

I want to be able to verify the authenticity of a QR code text without internet connection. Let's say I have a peanut butter store, and I have an online store too. After purchasing at my online store ...
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Using an alternative to shamir's secret sharing

I was wondering about the following as an alternative to secret sharing(shamir): Assuming that in order to gain access to some theoretical system, we'd be saving secrets on the system and we will ...
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160 views

What does Modification Detection Code (MDC) in OpenPGP do?

The authentication is often done by an HMAC in modern cryptosystems. What does MDC do exactly in OpenPGP and is it a software hack or an algorithmic authentication? Also, how to force GnuPG to stop ...
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how to predict a sequence for reverse engineering of a ticketing system [closed]

i am student in the fith year of college IT-science and a crypto noob. i have been wondering how the folwing sequence of ticket i bougth in all at once were built for : how they work or how they are ...
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Using ECDH for authentication

I've found this method for using ECDH for asymmetric encryption. Is there a similar method for using ECDH (rather than the more usual ECDSA, let's say my hardware can do ECDH but not ECDSA) to ...
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Very simple way of verification

In an application we need some way for a user to authenticate, but have the challenges of very restricted functions to use. Each user has got a 16bit-number he can't change. We want to calculate some ...
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Motivation for frequent key updates

I am wondering if there is any reason to regularly update cryptographic keys, that are used for authentication purposes in a real-time system. A key should be updated if it is weak, broken, ...
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Using encryption as authentication

I am building an app in which I would like to encrypt user data and support offline login. From this answer about using passwords for encryption: Best practice is to use a PBKDF to generate a 'key ...
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Noise NK1 pattern identity hiding

In the official documentation for the Noise Framework there is a section with an overview of the identity hiding for each pattern. The numbering of properties there, obviously, from weaker properties ...
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684 views

Is there a digital equivalent to the Great Seal of the United States?

Since antiquity (and, for ceremonial purposes, up to the present day) physical document have had seals affixed to them. In principle, these seals allow anyone, if he knows what he's looking for, to ...
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Are the signcryption and the authenticated encryption same?

The signcryption and the authenticated encryption are both the combine of encryption and authentication with three natural composition (i.e., EtS, StE, E&S). I am not sure that if they are the ...
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Can a MAC be used as a HMAC?

I am reading through an information security book right now, and a confusing question poses itself to me: "Could you use a MAC as a HMAC? That is, does a MAC satisfy the same properties that a ...
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32 views

Terminology for parties in authentication protocols

Is there a common terminology to designate parties in authentication protocols? For example, we typically use prover and verifier to designate parties with zero-knowledge proofs.
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How does AWS service verify the identity of the sender?

My question is regarding to : How does AWS Secret key and access key work The point 5: AWS service verifies the identity of the sender and integrity of the message by recomputing the HMAC code....
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111 views

Secretless authentication method for remote hardware

We're working with a microcontroller that is not secure enough to store secrets. The ROM could be dumped in a properly equiped lab. This is why we considered integrating a certified Secure Element ...
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199 views

Information security evaluation

I saw this exercise for evaluating the security(confidentiality, integrity, authenticity, and non-repudiation) of some schemes: ENC(M) || SignA(ENC(M)) ...
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Secure equivalent for giving an unknown card, applied to magician's card tricks

I suspect that this is already something trivial, but I can't find the answer, probably because I don't know how to search the cryptographic primitive that refers to my problem. Imagine the typical ...
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Authentication protocol

Alice and Bob share a secret key K. Suppose that someone suggests the following methods to allow Alice to securely authenticate to Bob. Bob generates a random message r, enciphers it using K under a ...

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