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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 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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1answer
20 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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23 views

MTI authenticated key exchange protocol and their vulnerabilities?

Can someone please explain the different MTI key exchange protocols (A0, B0, C0, C1) and their vulnerabilities. I've been trying to read about them but couldn't get much information.
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1answer
44 views

Computation power requirements for implementing cryptographic algorithms in small devices [on hold]

I want to estimate if a certain device can provide the cryptographic security functions. I would like to know what are the possibilities of implementation of cryptographic algorithms (encryption and ...
2
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1answer
132 views

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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0answers
22 views

Best authentication protocol to use Argon2 in?

I've seen that Argon2 is a very popular choice for hashing passwords, but which authentication protocol would it best be used in? E.g. can it be used in SRP?
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1answer
28 views

Authentication protocol for communication between Arduino Uno and Android device

I am using ECDH key exchange protocol for establishing shared secret between Arduino Uno and Android device. For this purpose I am using this library and more specifically Curve25519. This is the ...
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1answer
40 views

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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2answers
93 views

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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4answers
87 views

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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0answers
10 views

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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2answers
35 views

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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1answer
95 views

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 <...
5
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1answer
76 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 ...
1
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1answer
59 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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0answers
31 views

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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1answer
30 views

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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1answer
76 views

Where should I start to learn cryptography? [duplicate]

I want to learn cryptography. I just wanted to ask people who experienced about the field that where should I start? Any recommendation would be something for me. Thank you in advance.
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0answers
28 views

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 ...
3
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1answer
96 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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4answers
2k views

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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0answers
40 views

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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1answer
43 views

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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1answer
68 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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1answer
79 views

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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2answers
63 views

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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2answers
213 views

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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1answer
86 views

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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2answers
145 views

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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2answers
217 views

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 ...
3
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1answer
61 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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1answer
119 views

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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1answer
87 views

What can I do, if my SRP password verifier was stolen?

I've got a system that works like this: ...
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2answers
65 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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1answer
59 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 ...
2
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2answers
65 views

Authentication scheme to protect against fake devices

I want two embedded devices (call them master and slave) to communicate with each other. For intellectual property protection, the master must reject fake slave devices (the other way around is a pre ...
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0answers
32 views

How can I encourage non-techie users to authenticate PGP-signed documents (with keys not at a keyserver)

How can I encourage non-techie users to authenticate PGP-signed documents by verifying 1) a PGP fingerprint published elsewhere against a PGP public key included in the document (and not at a key ...
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1answer
102 views

Why is this authentication protocol with a nonce and tree parties not secure?

Why is the following authentication service not secure? C⟶S: $I_C$ S⟶C: $N$ C⟶S: $E(K_{C,A}, N)$ S⟶A: $E(K_{S,A}, \{I_C, E(K_{C,A}, N)\})$ A⟶S: $E(K_{S,A}, N)$ where: C = client S = server A = ...
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1answer
103 views

Is authentication more computationally expensive than encryption?

newbie in crypto here. I've a application that needs integrity protection. Confidentiality would be nice but has less priority over performance throughput. So I test "openssl speed" on my laptop, and ...
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0answers
54 views

Challenge/Response approach for mutual authentication

Why is challenge/response approach unsuitable for connectionless type of applications?
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1answer
65 views

merkle tree motivation

Here author seems to give overview of merkle trees. However, I have one problem. As in the article author claims you can use merkle trees to verify authenticity of data, e.g. if piece of data is ...
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1answer
46 views

Why exactly is a root hash used in relation to hash lists?

Wikipedia has an rticle about hash lists, although I find it technically not very detailed. For example: We could solve same problem by sending (authenticated) hash of each data block, together with ...
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1answer
84 views

ABE (attribute based encryption) vs ABS (attribute based signature)

I want to know if there is any shortcoming that ABE cannot achieve and that the ABS complete it. I mean why the ABS is included if the authentication and the authorization are already ensured by the ...
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0answers
53 views

PKI Challenge Response: why is $h(r) = x$ enough to protect against chosen text attacks?

I think the question was asked somewhere else but not answered very precisely. Quoting from the "Handbook of applied cryptography": Identification based on PK decryption and witness. Consider ...
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0answers
56 views

How does the authd protocol work?

So far, I have been able to research on what it is: authentication; authorization; using resource authd. I still have not come across a definitive answer or ...
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2answers
92 views

Plausibly deniable authentication for agents on multiple teams

Here's a problem that I've been thinking about: An individual, Alice, wishes to authenticate herself. She may wish to authenticate to Bob (who is on the blue team) that they are both on the blue team....
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1answer
41 views

Any Idea on this identification scheme's problem?

I was looking at the exercises of Cryptography theory and practice and I could not find the answer to this question anyone has an idea?
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1answer
53 views

Is symmetric encryption with a key containing the userId passes as authentication?

The scenario: There is a web application where ownership check is time expensive so during the development all users were able to access all other user's objects (let's say apples) by changing the ...
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0answers
147 views

Unknown key-share attack

In the unknown key-share attack a dishonest entity C tempts two honest entities A and B to establish a key shared between them. At the end of the attack, A believes she shares the key with B, but B ...
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1answer
83 views

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: ...