Skip to main content
New
Stack Overflow Jobs powered by Indeed: A job site that puts thousands of tech jobs at your fingertips (U.S. only). Search jobs

Questions tagged [key-exchange]

Key exchange protocols allow two parties to produce a secret session key over a public channel.

Filter by
Sorted by
Tagged with
0 votes
0 answers
24 views

Question about Environment Set in Universally Composable Security Proof

I have read into many papers and tutorials regarding "Universally Composable Security Proofs." I still have one confusion about the initial setup by the environment. On one hand, I got that ...
Novice User's user avatar
11 votes
1 answer
5k views

Is it possible to establish a shared secret over an untrusted unidirectional channel?

It there any way to, given a unidirectional channel, say a UDP messaging protocol, to derive a secret key and transmit information securely without prior knowledge of the other party? It sounds ...
Wesley Jones's user avatar
3 votes
2 answers
316 views

The advantages of using KEM compared to applying traditional PKE approach

I am studying a thesis on the design of a key encapsulation mechanism (KEM). In section 2.6 (page 18) of this thesis, the following explanation is given about the difference between KEM and common ...
User0258's user avatar
0 votes
0 answers
59 views

SampleNTT in Kyber [duplicate]

I was going through Kyber specification mentioned here - https://csrc.nist.gov/pubs/fips/203/ipd The SampleNTT is an algo used for matrix A calculation that takes XOF(p,i,j) as input. If the input is ...
Gappu's user avatar
  • 31
1 vote
2 answers
48 views

Is this procedural code correct description of `g is a primitive root module of p`?

I am a web developer with only high school level knowledge of math. I wanted to understand how TLS 1.3 is better than TLS 1.2. Along the way, I bumped into the concept of Diffie Hellman Key Exchange ...
learningtech's user avatar
0 votes
0 answers
32 views

Does Qrypt's BLAST protocol based on "Doubly-Affine Extractors" use public-key or symmetric-key cryptography?

The company Qrypt states that "Key distribution based on asymmetric algorithms is a weak link for cryptography" and claims to "enable encryption without distributing encryption keys&...
Very Tiny Brain's user avatar
1 vote
1 answer
146 views

A simple guide to Diffie-Hellman Key Exchange including the what, the how and the why

I'm tired of going online looking for a simple explanation of how the Diffie-Hellman Key Exchange works. Many guides I've found attempt to explain it using anything from "paint" to massive ...
suchislife's user avatar
4 votes
0 answers
123 views

What are the binding properties of post-quantum KEMs?

Performing a key exchange with post-quantum KEMs is very different to ECDH, which will likely cause vulnerabilities in protocols during the migration to post-quantum cryptography. One example is that ...
samuel-lucas6's user avatar
3 votes
1 answer
124 views

The weakening of PQC as a result of lack of KEX?

As far as I can tell we don't have any good key exchange post-quantum candidates. SIKE was broken some time ago. It is possible to reach an authenticated shared secret by having the public key holder ...
Squoomsquoom's user avatar
1 vote
0 answers
79 views

Ephemeral ECC refresh vs. simple hash ratchet

Some protocols employ ephemeral ECC key exchanges throughout the session. Such as the Noise framework. Is the rationale to do this simply because you can do it efficiently? To provide future secrecy ...
user avatar
2 votes
2 answers
307 views

RSA: Is padding necessary for key exchange?

When RSA is strictly used to exchange random shared secrets, is the padding scheme important for security or can it be omitted entirely? The party in possession of an RSA public key will generate ...
user avatar
2 votes
3 answers
238 views

Is any safe prime sufficient for a secure DH key exchange?

There are some very large safe primes listed here: https://en.wikipedia.org/wiki/Safe_and_Sophie_Germain_primes Would using any of them result in a secure DH construction? Generator is 2. The exponent ...
user avatar
2 votes
0 answers
73 views

Tor Key Exchange Client - Middle Node

I am currently exploring the workings of the Tor network, specifically how the Diffie-Hellman (DH) key exchange protocol is employed to establish shared secret keys between the client and each relay ...
Elian's user avatar
  • 21
4 votes
0 answers
107 views

Impossibility of uniform generation in random world

I was reading Limits on the provable consequences of one way permutations by Impagliazzo and Rudich when I got stuck on a sentence. First of all, they define a polynomial relation that is any relation ...
Pur2all's user avatar
  • 60
1 vote
1 answer
433 views

Key exchange for encrypted firmware update

I'm trying to implement encrypted firmware update functionality for an embedded device. The goal is to prevent reverse engineering of our firmware when the update files are shared with our customers. ...
MDude's user avatar
  • 23
3 votes
2 answers
204 views

What is the difference between Post-Compromise Security and Backward Security?

Post-Compromise Security and Backward Security seem to mean that the attacker has obtained the communication key between two parties or groups in the current state, but cannot further obtain ...
Guardzhan's user avatar
1 vote
0 answers
56 views

Graph-based key exchange

Alice and Bob fix a largish $n$, say $n = 1000$, and they publish a simple, undirected graph $G$ on $n$ vertices (more precisely, its adjacency matrix, or a similar form of representation). Moreover ...
Dominic van der Zypen's user avatar
1 vote
1 answer
178 views

TR-31 Key Exchange Mode of Use

Using TR-31 key exchange, how is it possible to use restrictive modes of use, such as V (Verify only)? If Alice were to generate such a key, and send it to Bob, Bob would not be able to generate a MAC ...
Jonathan Rosenne's user avatar
1 vote
0 answers
31 views

Can an attacker impersonate any party in a modified Needham-Schroeder protocol?

We are doing symmetric Needham-Schroeder protocol in university. We were provided a modified protocol and needed to answer the following questions. Original protocol: Modified protocol: Task a) An ...
PCFX's user avatar
  • 63
1 vote
0 answers
178 views

TLS 1.3 key_share capture without certificate exchange

I am working on an investigation on TLS 1.3. I've came across an article of qacafe where they shared a TLS 1.3 handshake sequence. Wireshark capture. In this capture you see that in the Client Hello a ...
Arthur Timmermans's user avatar
1 vote
1 answer
47 views

Security of keys that are as long as the data

If both communicating sides end up with the same secret 3000-bit key, is it enough to XOR each byte of the messages with each byte of the secret key to make it secure? Wikipedia says it is, but I ...
Kevin Stefanov's user avatar
0 votes
1 answer
130 views

who creates the passkey (and how many will be created)? [closed]

Passkey is nice. The math is nice. The tech is nice. https://security.googleblog.com/2023/05/so-long-passwords-thanks-for-all-phish.html What I still dont see after sooo many hours: what software ...
r j's user avatar
  • 101
1 vote
1 answer
249 views

For TLS-PSK (pre-shared key), should non-ephemeral key exchange be preferred over ephemeral one?

TLS 1.3 specify two pre-shared key exchange modes, which are psk_ke and psk_dhe_ke. The former is a non-ephemeral key exchange ...
Du Huynh's user avatar
0 votes
2 answers
99 views

Key exchange from discrete logarithm only

Diffie-Hellman key exchange is sometimes informally said to be hard under the discrete logarithm assumption in the chosen group. But if I am reading literature correctly, it actually uses a stronger ...
Ilk's user avatar
  • 233
1 vote
0 answers
58 views

Linux Kernel CryptoAPI key exchange and key derivation

I have a custom network and I want to implement a symmetric key exchange and key derivation mechanism with ECDH. I know that I need to use KPP API and ECDH helper functions, but I can't find any code ...
Ham's user avatar
  • 11
0 votes
0 answers
193 views

How do I decrypt a key encrypted by my HSM under a ZMK?

I've generated a key using an HSM Thales PayShield and i have share it with a counterpart. I followed these steps: i generated key usign KG console command i use FK to form ZMK from clear components ...
MaXbeMan's user avatar
0 votes
0 answers
149 views

PCI compliance - use of ANSI X9.17 for export keys

we have a concern about a key export. We completed the migration to Key Block LMK in our environment (with HSM Thales 10K). Now, we have to exchange keys with third-parties that still use Keys in ...
MaXbeMan's user avatar
0 votes
1 answer
210 views

Clarification on the use of Key block Version ID with Thales HSM

Clarification on the use of Key block Version ID For the first time since we migrated to the Key Block we are exchanging keys with third parties, The keys were all generated by choosing Key Scheme &...
MaXbeMan's user avatar
4 votes
2 answers
161 views

Why NIST 800-56A rev3 does not use cross secret calculation in C(2e, 2s, ECC CDH) scheme?

In the NIST 800-56A rev3 "Recommendation for Pair-Wise Key-Establishment Schemes Using Discrete Logarithm Cryptography" in section 6.1.1.2 "(Cofactor) Full Unified Model, C(2e, 2s, ECC ...
obareey's user avatar
  • 117
3 votes
1 answer
515 views

How does TLS 1.3 restrict the Diffie-Hellman parameters to ones that are known to be secure?

In previous versions of TLS, the choice of the Diffie-Hellman parameters was up to the participants. This resulted in some implementations choosing incorrectly, resulting in vulnerable implementations ...
user10433098's user avatar
2 votes
1 answer
80 views

Mutual authorization using a pre-shared key

I'd like for two machines on a network to be able to prove to each other that they both have knowledge of a pre-shared secret, without revealing the secret to each other. Let's assume that all traffic ...
Kira's user avatar
  • 21
2 votes
1 answer
188 views

Authenticated Key Exchange of Kyber.AKE

I have some questions about the setting of the one-way authenticated key exchange of Kyber.AKE as defined in section 5 of the paper. How does $P_2$ authenticate itself to $P_1$? It is not obvious to ...
P_Gate's user avatar
  • 413
0 votes
1 answer
76 views

How can I send someone a large file safely without using key exchange protocols (for encryption)?

I recently took an exam where one of the questions was roughly the following: You need a specific way for sender S to send a large file M to a receiver R with their secret-public key pair, without ...
smitc29's user avatar
  • 23
2 votes
1 answer
55 views

Two way key transport?

For a KEM mechanism like RSA, Kyber, etc. is there it usually worth doing key trapping/key encapsulation both directions in a key exchange? By this I mean: Alice wraps a symmetric key and sends it to ...
Joe's user avatar
  • 73
1 vote
1 answer
131 views

DH Finding A Public Key from Public key and shared secret

Is there a known feasible method for determining an unknown public key from a Diffie Helman shared secret and the other public/private key pair? This would be rarely useful, but I am curious if the DH ...
Wesley Jones's user avatar
3 votes
0 answers
143 views

Compute key size in Hyperelliptic Curve Cryptography

I am trying to implement a basic Diffie-Hellman key exchange using ECC and HECC of genus 2 and 3 and compare them. However, I am a bit confused about the concept of key size in HECC. In ECC, from my ...
PanosDgs's user avatar
2 votes
0 answers
46 views

A tensor-based Diffie-Hellman exchange

Below is a description of a "cube" Diffie-Hellman, based on commuting matrix actions on tensor products. Some questions: References for something similar? Obvious flaws, is this a terrible ...
yoyo's user avatar
  • 420
2 votes
1 answer
166 views

How to combine the keys in the Triple Diffie-Hellman (3DH) key exchange?

I was reading up on the Triple Diffie-Hellman (3-DH) key exchange and noticed that the wikipedia description [1] is different from the the original protocol definition [2] and the modified definition [...
n-l-i's user avatar
  • 547
7 votes
3 answers
3k views

Why did post-quantum key exchanges go extinct?

On July 5, 2022, NIST chooses one KEM (Key Encapsulation Mechanism) as a PQC standard and 4 KEMs as four-round candidates. Why aren't there any key exchanges? Similarly, KEMs are usually studied in ...
user's user avatar
  • 183
1 vote
0 answers
97 views

What is the most secure hybrid cipher suite(Library) possible today?

What combination of public key cryptography (DH) and symmetric key cryptography is currently available that is (subjectively) as secure as possible over other ciphers (AES,curve448) when security is ...
nitchan's user avatar
  • 137
2 votes
1 answer
155 views

A perfect key exchange similar to the One Time Pad

The one time pad is unbreakable because each message could be one of many, and each one is equally likely. Is it possible to do this with a key exchange? (So if someone records the key exchange, there ...
undefned's user avatar
1 vote
1 answer
184 views

McCallum-Relyea exchange on x25519 elliptic curve

Background I have a degree in electronics engineering, I'm not bad at programming with many languages, but I'm not that good at cryptography, I'm just able to use that from libraries, and I understand ...
Luca Anastasio's user avatar
0 votes
1 answer
300 views

RSA Key Exchange Attack [closed]

I am curious what is an attack that the RSA Key Exchange algorithm is vulnerable to that Diffie Hellman Key Exchange is not vulnerable to? I know Diffie Hellman is prone to Man in the Middle attacks ...
CryptoGuru's user avatar
2 votes
0 answers
133 views

Explanation of Burmester-Desmedt group key exchange and Ingemarsson-Tang-Wong (ITW) group key exchange algorithm

I know that both algorithms are similar to the Diffie-Hellman key exchange and are used for exchanging secret keys in a group but I still cannot figure out the key differences between both algorithms. ...
Haidepzai's user avatar
  • 121
0 votes
1 answer
103 views

Can you use MITM to hijack a public key meant for key based signing?

After reading "Verify the identity of sender" , which was part of an answer on StackOverflow, I was wondering if the following is possible: Based on part II, if I am sitting between Alice ...
Tom's user avatar
  • 5
1 vote
1 answer
97 views

Blom's key distribution

Having a difficult time wrapping my head around the Blom's key distribution. I found an online resource to understand this but still couldn't get it. I am attaching the screenshot from the book where ...
jammy's user avatar
  • 111
0 votes
1 answer
452 views

Defending MITM attacks during key exchange

As far as I know, key exchanging algorithms are vulnerable to an active MITM attack. Let A (Alice) and B (Bob) be parties with no secret information. An adversary C playing man-in-the-middle ...
imamangoo's user avatar
0 votes
1 answer
53 views

Mapping DH / DHE p & g params to a group

I'm doing a small code that performs a simple SSL/TLS analysis and I'm stuck on determining the size of the key exchange in the case of DH / DHE. If I take the following example (wireshark capture) : <...
Akerces's user avatar
1 vote
2 answers
2k views

How does TLS 1.3 provide authentication without using the public key to verify that the server has a private key?

In the TLS 1.2 handshake, after checking the certificate, the public key from the certificate was used to encrypt the data to create a symmetric encryption key, hence the authentication took place on ...
Nikita Khodakovsky's user avatar
0 votes
0 answers
54 views

minimal public-key authenticated encryption protocol

One party (master) wants to send data to another party (slave) over an insecure channel using public-key encryption and signature schemes such that: master is authenticated, data is confidential, ...
yoyo's user avatar
  • 420

1
2 3 4 5
14