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.

Filter by
Sorted by
Tagged with
3
votes
3answers
140 views

Group membership with unique anonymous claims

Is it possible to accomplish the following scheme? There is a Server (S) and many clients. Each client enrolls with S, exposing its real identity; S saves the real identity information in its ...
4
votes
2answers
332 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, ...
0
votes
0answers
21 views

Why is authentication needed between Alice and Ticket Granting Server in Kerberos Protocol

Being the messages of the protocol: With KAS = Kerberos Authentication Server, TGS = Ticket Granting Server, B is a service and T1 T2 T3 T4 are timestamps. I was wondering why is the "...
2
votes
2answers
77 views

Why does a nonce prevent a replay attack?

I have a question about a cryptographic nonce. I understand the use of a nonce, however there is one particular part that I don't understand. Please consider the picture below. I don't really ...
1
vote
1answer
116 views

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 ...
0
votes
1answer
62 views

Crypto AES for authentication

Is it secure to use authentication strategy like this: store key in database - crypto.randomBytes(32) store IV and encrypted data in user cookies - ...
0
votes
0answers
38 views

If we have chunk encryption for AES-Rijndael-CBC, should we hash Authenticate/tag each single chunk with a hash vs whole file?

was frustrated by which one to pick and my brain could not guess which one is better Authenticate the whole file as one with a hash vs authenticating each ciphered text. So very quickly: i have super ...
0
votes
1answer
47 views

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 ...
0
votes
1answer
58 views

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 ...
0
votes
0answers
23 views

Unilateral Authentication hash type for verification

The scenario: Alice wants to exchange information with Bob on an encrypted channel proxying through Pete (Pete can't read the info sent between Alice and Bob), but doesn't want Bob to know who she is, ...
2
votes
0answers
37 views

Is the first Nonce exchange between Alice and Bob in Needham-Schroder key exchange protocol redundant?

For the Needham-Schroder protocol, assuming Alice and Bob are both able to guarantee each other's public keys (e.g. through a Certificate authority), the protocol is 1) A sends to B: $E_{publicB} [...
2
votes
1answer
93 views

How is Diffle Hellman with RSA immune to man in the middle?

Alice and Bob want to exchange keys, Alice sends his half (the public key of the ephemeral key pair) signed with his private key and makes the public key available. Eve is bridging the connection so ...
1
vote
0answers
27 views

TLS client authentication from static client image

I'm trying to implement mutual authentication for a TLS connection between a server (ONOS OpenFlow controller) and multiple clients (OpenFlow switches). I'm restricted in that I must create a single ...
1
vote
0answers
20 views

CHAP vs EAP-MD5

I started studying EAP authentication framework and I don't understand why was the EAP-MD5 developed. Why not just use the CHAP protocol ? To me they seem the same. Can you explain to me ?
2
votes
1answer
36 views

Non Repudiation - Message Authentications methods

According to a definition given by my professor: Message authentication methods verify that the message is from the right sender, however they don't guarantee non-repudiation. To me this sounds ...
0
votes
0answers
47 views

Where are labels of a Labeled data used in homomorphic message authenticator stored?

In a fully homomorphic message authenticator, Alice can authenticate some large data $D$ using her secret key $s$k. She chooses a label $\tau$ for it, and the authentication algorithm authenticates ...
2
votes
1answer
177 views

How does Gilbert, MacWilliams, and Sloane's solution to “perfect integrity” work?

Gilbert, MacWilliams, and Sloane defined a solution to "perfect integrity" in Codes Which Detect Deception, unconditionally secure message authentication, not vulnerable to any cryptanalysis on its ...
2
votes
1answer
222 views

Proof of shared secret through key derivation

Alice gives a random key $K$ (e.g. 32 bytes long) to Bob through a secure channel. Bob want to prove to Alice through an unsecured channel that he knows the key. Is it secure for Bob to send $s||KDF(...
1
vote
1answer
390 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-...
0
votes
2answers
76 views

Is there a reason to use multiple hashing algorithms in a single system?

I came across an authentication system Here that uses multiple hashing algorithms to hash data in different stages of the authentication. My question is what's the rationale behind this? If a hashing ...
0
votes
1answer
540 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 ...
1
vote
0answers
36 views

Lightweight provably secure design [closed]

Is it possible to device lightweight (i.e. without asymmetric crypto and PKI; and without third party Trent) provably secure (in the exact security sense) scheme? Were there any attempts? Is it ...
3
votes
2answers
180 views

Authentication over the phone?

Are there any known good methods of performing authentication over the phone in a way that's not susceptible to replay attacks? The specific scenario that comes to mind is having an automated call ...
2
votes
1answer
81 views

Existence of MAC implies existence of OWF

I'm having trouble understanding how the existence of a MAC implies the existence of an OWF. If the MAC protocol is $(\operatorname{Gen}, \operatorname{MAC}, \operatorname{Ver})$ such that for any ...
0
votes
0answers
21 views

Question about PKI-based non-deniable authentication by Canetti et al

In Universally Composable Authentication and Key-Exchange with Global PKI, Canetti et al. proposed a non-deniable authentication functionality as well as a protocol that GUC-emulates it. My question ...
0
votes
0answers
43 views

Digital signature forging on a server, after entity authentication [duplicate]

Lets assume there is a guy called Ben, he contacts some server for a ticket number and the server returns a random number to him. Ben then signs that number and sends it back to the server, which ...
9
votes
1answer
8k views

Where is the authentication tag stored in file encrypted using AES-GCM?

So I am using cryptopp to encrypt a file in a project and I am using AES-GCM. I have a 256bit key and a 128bit ivec and a 128bit tag that I use to encrypt files. However, I want to know where the ...
1
vote
1answer
67 views

Is using HMAC signature as a long-term password secure?

I'm considering implementing an authentication service without storing users' passwords/hash. I want to use a key derivation function with a corresponding username...
0
votes
0answers
31 views

Unconditionally secure message authentication, how does it work? [duplicate]

The definition of an unconditionally secure cryptosystem is that it cannot be broken even with infinitely computational resources and time. The one-time pad (OTP) is an example of an unconditionally ...
0
votes
4answers
926 views

Why do one-time pads not provide message authentication?

It is often said that one-time pads do not provide message authentication. But, if you and I have a one-time symmetric key, and I send you a message, and it is not complete gibberish, is that itself ...
2
votes
2answers
171 views

How to Understand Authenticated Key Exchange?

I am reading some articles about key exchange. I know classic key exchange, such as Diffie-Hellman key exchange. This type of algorithm is vulnerable to man-in-the-middle attack. However, when using a ...
6
votes
2answers
1k views

Is there another resource for Carter-Wegman-style message authentication?

I'm wondering if there are other resources that cover Carter-Wegman style message authentication, besides the sources themselves. Is there an online text or a book that covers their ideas? I'd ...
0
votes
1answer
58 views

HMAC based Key exchange

Alice and Bob need to share public keys to sign/verify ephemeral keys. They have a secret key $K$. Alice generates a 32 bytes random number $A$, computes $\operatorname{HMAC-SHA256}(K, M||A)$ and ...
4
votes
1answer
133 views

Pen and Paper Authentication

What is the best way to prove that you wrote the encrypted message on a piece of paper? As most of us know, many conspirators have died because of false message implants, Mary Queen of Scots, for ...
5
votes
1answer
144 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 $P_B$...
0
votes
1answer
32 views

Is it necessary to have a certificate when we use TLS

When we say a communication is secured by the latest version of TLS, can we say that Man-in-the-Middle attack is not possible? Do not consider the situations that we can down grade the communication ...
1
vote
1answer
99 views

How are AEAD, GCM, CBC, Poly1305, EtM, MtE and E&M related?

I am using OpenSSL 1.1.1 to implement a TLS 1.3 communication module so I tried to learn how data integrity and authentication is ensured. I read a lot about AEAD, GCM, CBC, Poly1305, EtM, MtE and E&...
7
votes
3answers
556 views

What is the reason to separate domains in the internal hash algorithm of a merkle tree hash?

From rfc 6962 It is stated that: Note that the hash calculations for leaves and nodes differ. This domain separation is required to give second preimage resistance. That means that ...
3
votes
1answer
1k views

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 ...
4
votes
2answers
419 views

How secure are public hashed passwords (with a salt)?

I'm working on a blockchain-based distributed application which stores Client information. I'm thinking of alternate ways to authenticate ...
0
votes
2answers
111 views

Is there a human readable easier version to represent PGP Private keys?

I'm working on a distributed application, and we need a way to authorize clients. Every client has a PGP keypair associated with them, and we require them to enter their private key (which is not ...
0
votes
0answers
32 views

What is used as a KEY and MESSAGE when using HMAC within a PBKDF2? [duplicate]

I was studying WPA2 and it's security when I came across this problem. I know that WPA2 uses PBKDF2 to generate a Pairwise Master Key. It does something like this; ...
3
votes
0answers
1k views

Can you help me understand this toy example of ECDSA signing and verification? [closed]

I'm a complete newbie to ECC. but I was trying to get my feet wet with (what I thought would be) a TRIVIAL/EXTREMELY SIMPLE example of ECDSA signing and verification (that I could check by hand). I'd ...
3
votes
3answers
89 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 ...
0
votes
1answer
158 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 ...
14
votes
2answers
10k views

Storing Credentials for a Third Party

(Originally posted to SOF, but I got no answers) I am designing a small application for use inside my company. My application needs to connect to a third party website on behalf of my application ...
1
vote
1answer
274 views

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.
0
votes
0answers
46 views

Authenticating without sending password to the server, and store data encrypted with password derived key on server

I am trying to think of a scheme that would allow a user to authenticate to a server, whithout sending the password to the server, and to also derive a symetric key on the client (that also never gets ...
0
votes
1answer
211 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.
2
votes
0answers
54 views

What security is provided by a certificate? [closed]

I've been working on the topic of certificates for a little while, and here is what I understand: A certificate is basically a public key + some data about the owner of the certificate + a signature ...