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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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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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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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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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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Is it safe to reuse ECDH asymmetric keys for authentication?

Alice, Bob, and Carol each generate ECDH keypairs. Alice and Bob establish a communication channel and negotiate an AliceBob secret. The question is: Is it safe for Alice and/or Bob to reuse their ...
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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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Does humanly verifiable one time pad authentication exist?

Firstly some predicates:- Sufficient hardware generated one time pad key material. No pad reuse. Messages of 160 characters length (think Twitter). 28 characters only in use (A-Z, space and full stop ...
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What are the differences between a digital signature, a MAC and a hash?

A message may be accompanied with a digital signature, a MAC or a message hash, as a proof of some kind. Which assurances does each primitive provide to the recipient? What kind of keys are needed?
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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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Does the AES-KW (Key Wrap Algorithm) perform authenticated encryption?

The RFC for AES-KW doesn't actually mention authentication. It only mentions integrity, where the unwrapping/decryption process should produce an identical IV of ...
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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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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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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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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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Diffie-Hellman Key Exchange with Authentication: Man-in-the-Middle query

I have been reading up on MiTM attacks, and the prevention of them using public key certificates. Recently I learnt about Diffie-Hellman Key Exchange with Authentication, and how it uses signed ...
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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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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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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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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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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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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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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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Counters in HOTP

In the HOTP (HMAC-based One-time Password algorithm ) algorithm the client and the server can have different counter values. Es. if an attacker tries to crack the password with no success. How HOPT ...
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Key exchange and authentication using libhydrogen

I have been able to exchange session keys on two devices using Libhydrogen's Key exchange using the N variant method. I also want to authenticate both devices to have some protection against the Man ...
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Primitive root in a finite field

Wen-Her Yang and Shiuh-Pyng Shieh proposed two password authentication schemes by employing smart cards, one is timestamp-based and the other one is nonce-based. Their scheme consists of 3 phases: ...
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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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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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Why is the GHASH output in GCM mode encrypted to calculate the tag?

To calculate the authentication tag in the Galois/Counter mode (GCM), first a MAC is calculated using GHASH over the cipher text and the additional data. After that, this MAC is encrypted using GCTR (...
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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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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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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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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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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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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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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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