Questions tagged [key-exchange]
Key exchange protocols allow two parties to produce a secret session key over a public channel.
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How exactly does ASKE (Alpha Secure Key Establishment) in Zigbee work?
I am working on Zigbee security. For key establishment, some approaches are given in Zigbee. Some of them are:
ASKE (Alpha Secure Key Establishment),
ASAC (Alpha Secure Access Control), and
SKKE (...
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Differences between “NewHope” and “NewHope-simple”
The well-known paper described a key exchange (KE) scheme named "NewHope" on USENIX 2016. The authors then proposed "NewHope-Simple" - a PKE/KEM scheme. They also submitted "NewHope for NIST" - ...
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How many qubits are required to break classical Diffie-Hellman?
There have been comparisons between RSA and ECDH with regards to the number of qubits required to break the algorithm with a specific key size. But how many qubits are required to break "...
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About a SETUP mechanism on ECDH
I'm following these three articles:
Kleptography: Using Cryptography Against Cryptography,
Kleptographic Attack on Elliptic Curve Based
Cryptographic Protocols and
Elliptic Curve Kleptography .
In ...
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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 ...
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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 ...
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How to modify the Socialist Millionaire Protocol to be symmetric.
In the Socialist Millionaire Protocol, the roles of Alice and Bob are almost symmetric. By this I mean they do almost the same thing, until the very last step.
In the final step, both parties check a ...
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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 ...
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How to extract an AES key which resides in a TR-31 keyblock
I have a version D TR-31 keyblock (which contains an AES Key for use in CMAC), and have the ZCMK key used, what is the method which I can use to extract the key from the TR-31 keyblock? I'll do my own ...
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XDH vs DH and ECDSA vs EDDSA
I am new to security area. I came across mutiple words I can't understand and there is little infomration I can get from google.
What is XDH/XEC, is the X means 'enhanced'? Are they just have a ...
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Use of nonces in the SIGMA protocol and not in C(2e, 2s) of NIST SP800-56a?
While reading the paper on the SIGMA: the ‘SIGn-and-MAc’ Approach to Authenticated Diffie-Hellman and its Use in the IKE Protocols (Krawczyk,2003), I noticed that in the "full-fledge" ...
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Where shoul I store private/public keys and how should I share it?
I'm new in terms of encryption and I have to encrypt the data between two Java Spring applications, one have serves as MVC framework and other as Web Service, I'm implementing an asymmetric encryption ...
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show how LWE errors can have a greater impact on result
Hi weve been given the following question in one of our classes but have not been taught anything about it and is worded strangely. It is to show how the LWE problem works by showing how small errors ...
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Telegram VoIP key exchange
We've been trying to understand how Telegram's VoIP end-to-end encryption works.
Key Exchange
Detailed description of the key exchange algorithm is documented on the Telegram website.
Here is the ...
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How subscriptions are managed in PayTV securely?
Since there are millions of subscriber for each operator in PayTV and each subscriber can subscribe to any of the package or individual channels, how operators transmit Entitlement management messages ...
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Can I get an explanation of HDCP's key exchange protocol?
I'm talking about HDCP v1.x. The specification is a too dense for me and easy-to-understand information about it on the net is scarce.
What I've gathered is:
that there is a master key that is a 40-...
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Is MITM possible after key exchange phase done successfully in RSA?
Is MITM attack theoretically possible after public/private key pair exchange is done successfully? Say Alice and Bob have genuine public keys of each other. Is MITM possible further during the ...
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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 ...
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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 ...
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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.
...
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SSL/TLS Forward secrecy with 2 KEM public keys
As we know, NIST PQC project is at its 3rd round, with draft standard expected to arrive in the next (few) year(s).
An unfortunate fact is that, we're not seeing many signature schemes general-purpose ...
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Negotiating a session key, when only one public-key is exchanged via QR Code
Question
I want to create a secure channel between a server and a client. It is only important that the client can verify the identity of the server, not the other way around.
In my special case, an ...
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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 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} [...
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Proving the lack of Perfect Forward Secrecy
In specific regarding the NSA's Key Exchange Algorithm, I read in an analysis of the protocol that perfect forward secrecy cannot be provided.
Is there any way to prove or justify this? I couldn't ...
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Key update and re-keying
What is the exact difference between the key update and re-keying? Following the discussions here, I understood that the key update is the process of deriving the new session key from old key. In the ...
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Multi-Authority (KGC) Certificateless Cryptography
I'm thinking to a particular scenario where I'm adopting the certificateless cryptography (the generic schema) where I have 2 trusted nodes, that we can identify as: $KGC_1$, $KGC_2$. Furthermore, I ...
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breaking anonymous key exchange protocol
An anonymous key exchange protocol $P$ is pair of probabilistic machines $(A,B)$ that sends messages to each other and at the end, both $A$ and $B$ will share the same key $k$.
The attacker can see ...
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Symmetric (in the execution of the protocol by the two parties) version of the Station-To-Station protocol?
The original Station-To-Station (STS) protocol is as following:
Alice : Generate $x$
Alice → Bob : $g^x$
Bob : Generate $y$, compute $g^y$
Bob : Compute $K = (g^x)^y$
Bob : Sign-then-Encrypt $(g^y, g^...
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Is Diffie-Hellman key exchange for multiple parties used in practice?
After reading this question about the possibility of using DH key exchange for multiple parties I went looking for a (C) library able to do this and found none.
(I find it hard to believe there is no ...
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What's a good security schema for many to many communication?
Assuming you have a "typical" group chat-room, with n participants connected together by a server (the server handles message routing).
Would be a good security schema which would allow for encrypted ...
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Fair exchange vs Exchange of secrets
I have started reading
"How to Exchange Secrets with Oblivious Transfer" (PDF)
"On the impossibility of fair exchange without trusted parties" (PDF)
I found the abstract of those these two work to ...
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Asymmetric vs symmetric encryption
I am a beginner learning about encryption and I would like to ask a few questions, hoping this is the right place to ask, so please bear with me.
We have Alice and multiple clones of Bob. Only Alice ...
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ABE Cryptography - Send user private key
I am studying Attribute Based Encryption. Now my study concerns CP-ABE scheme. The authority make users private keys using attributes and a Master Secret Key (of Authority). How can the authority send ...
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Using a Secure RNG in Probabilistic Fair Exchange
I am attempting to implement probabilistic fair exchange described in Probabilistic Non-Repudiation without Trusted Third Party.
A secures a message using AES with 512 bit keys (in my implementation)....
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Is it possible to perform one-way Diffie-Hellman MITM?
Here's something that is bugging me recently: suppose that me and my friend establish an OTR session and - as a result of that - DH key exchange is performed. My friend verifies my key, but I cannot ...
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Malicious KGC attack in the identity-based authenticated key exchange protocol
There are two users $A$ and $B$ who are in different domain. Let's assume that $A\in KGC_1$ and $B\in KGC_2$. If they want to establish secure session, then they must run an identity-based ...
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Common pitfalls of session key activation?
Assume that initiator $I$ and responder $R$ of a key agreement protocol have agreed on new symmetric session keys $K'_{auth}$ and $K'_{enc}$, e.g. by way of Diffie-Hellman and key derivation, possibly ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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Developing a Simmetric Key Distribution protocol to use with rfc6238
I'm trying to develop a Key Distribution Protocol to share symmetric keys in RFC 6238 (OTP).
I started with RFC 6063, but this protocol is developed over old and known insecure algorithms like PBKDF ...
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The Responsibility of Key Exchange
I've been implementing an asymmetric key exchange for creating a symmetric key.
My question is more of a philosophical/legal one in terms of key-exchange responsibility, and what happens when let's ...
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Combining Post-Quantum and Classical KEM
I came across this paper "Hybrid Key Encapsulation Mechanisms", were three methods are defined that allow a secure combination of a classical key encapsulation with a post-quantum key ...
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CK vs BR Key Exchange Security Models
I'm writing a paper on Authenticated Key Exchange Protocols. I've read Bellare and Rogway's seminal paper on the subject and I think I understand BR Model and I'm now reading Cenetti and Krawczyk's ...
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How to decrypt raw TLS bytes?
Is there any tool / way to decrypt raw bytes of a TLS 1.2 session, when the master key is known, even if forward secrecy is used?
The closest I found is this.
I know its possible using Wireshark, but ...
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How efficiently can an attacker forge parts of a fingerprint?
If two devices do not trust each other yet, you can't simply send the correct fingerprint across: you have to manually verify it. I am looking into the security of comparing only random parts of a ...
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