Questions tagged [diffie-hellman]

Diffie-Hellman is a method for establishing a shared secret that can be used as a cryptographic key.

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Question about Diffie-Hellman key exchange

It is known that a man-in-the-middle attack on the Diffie-Hellman key exchange protocol in which the adversary generates two public-private key pairs for the attack. Could the same attack be ...
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Bluetooth keys for QR code pairing

Lets suppose we have two devices A and B that want to connect over BLE using OOB pairing with QR codes. I am asking myself whether the transmitted DH keys are static. At least the information provided ...
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I don't understand TLS 1.3 allowing PSK

TLS 1.3 removes the use of non-ephemeral Diffie-Hellman, which is great! But it still allows PSK. I'm not as familiar with PSK configuration but wouldn't that mean TLS 1.3 still is allowing the use of ...
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How does the inclusion of a subprime q value affect the Diffie Hellman equation for key exchange? [duplicate]

This is a follow on from this question: "Diffie-Hellman Key Exchange" in plain English In the answer to that question, the standard Diffie Hellman key exchange equation is derived: (g^a mod ...
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Is this scenario of static ECDH public key exchange right?

I'm thinking about the way to build encryption mechanism for 'peer-2-peer' communication. This is a mechanism I had a thought of: Alice wants to communicate with Bob First of all, Alice and Bob must ...
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Key generation between Tiny-C-ECDH and cryptography.hazmat.primitives.asymmetric.ec [closed]

I have two systems, one running a C environment on a RTOS and another a python program running on a Pi. I need to generate an encryption key using ECDH between these two systems for symmetric ...
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ESP32: Secure WiFi credentials via WebCrypto?

Background information: I am not a computer scientist. However, in a research project I am currently building a ESP32-based sensor. Multiple sensors of this type are going to be used by multiple users....
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In Diffie-Hellman, why is the shared secret guaranteed to be the same? [duplicate]

In general, I understand the principle of Diffie-Hellman key exchange. What I don't understand is what is so fundamental about primitive roots modulo p that guarantees that the shared secret is the ...
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Cracking diffie-hellman public key to obtain shared key

I'm given 2 prime numbers, g and n, as well 2 public keys, ga mod n and gb mod n, as part of a leaked Diffie hellman key exchange. I need to derive the shared key gab mod n using the given information....
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How does the Client Random and Server Random work when they are public? [duplicate]

I have read this section and I am still a little confused, as well as read a few of the posts here: https://www.acunetix.com/blog/articles/establishing-tls-ssl-connection-part-5/ So, the client sends ...
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Explain the three versions of Diffie-Hellman used in SSL/TLS

I understand how Diffie-Hellman algorithm can be used to agree on a common key between a client and server. I am struggling to understand the three variations of Diffie_Hellman - Anonymous Diffie-...
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Diffie–Hellman key exchange in TLS 1.3

I am reading about the Diffie–Hellman key exchange in TLS 1.3. So the first step here is that the two parts Alice and Bob t agree on a large prime p and a nonzero integer g modulo p. Then Alice and ...
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symmetric key generation in TLS 1.3

Am trying to understand the phase where the symmetric key is getting generating. From what I am understanding Diffie-Hellman is used to derive the symmetric key in TLS1.3 I am reading this tls ...
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Does this seem like a secure way to transfer wireless data from a keyboard to a host?

I'm making an adapter to convert a wired keyboard I have into a wireless keyboard. I am going to use nRF2401 modules for wireless with some STM32 microcontrollers. I'm trying to come up with a method ...
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How to generate ffdhe from rfc7919

Everyone recommends to use the pre-defined ffdhe groups from https://www.rfc-editor.org/rfc/rfc7919 There are multiple sources (for example mozilla) where I can download the DH PARAMETERS file but how ...
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What will be the key size for rsa, ecdhe and ecdsa from the cipher suite given?

From the cipher suites tls_rsa_with_aes_128_cbc_sha256 and tls_ecdhe_ecdsa_with_aes_128_cbc_sha256 how do I know what will be the RSA , ECDHE, and ECDSA key support in IBM cloud Watson? here is the ...
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How to use another SSL certificate for DHE-RSA while I already have one with domain?

I'm working in IOT team to build a web based IOT system. I'm using Dataplicity's Wormhole to host my nodeJS app on raspberry pi. I want to use DHE-RSA symmetric key encryption channel for sending/...
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Can a secure key-exchange algorithm replace hashing for password authentication?

Over the weekend I was thinking about the problem of scaling various web services. One common practice to scale authorization is to use cryptographically signed tokens. This way when a request comes ...
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how to encrypt and decrypt messages with more than one sender and more than one receiver?

I am creating a chat app. This app contains private messages and channels. These channels include more than one user. I want to encrypt messages using AES and to transfer the AES key to users of this ...
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RSA key exchange

I want to create a message exchange program. These messages are encrypted with the AES key, and this key is encrypted using the RSA algorithm. When I send a message from User 1 to User 2, I need to ...
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Diffie Hellman implementation- NodeJS

Diffie Hellman is a key exchange algorithm where client and server both generate public and private key, exchange their public key and combine this key with his own private key to generate same secret ...
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Why can't we encrypt the message with sender's private key and receiver's public key in case of sending messages through a server?

I read that why do we need E2EE and can't rely only on HTTPS for sending messages through a messaging app. The reason which i understood is when sender sends the message to the server, the TLS ...
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Performance comparison between ed25519 vs AES

I found that AES has dedicated hardware on most machines. The question is can we use ed25519 to replace AES? Instead of using RSA to encrypt the AES key and then encrypt the data with AES, can we just ...
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how to send prime and generator of diffie hell-men to client over network node js?

I am using crypto module of node js for exchanging key using diffie-hellman algorithm. server.js const crypto = require("crypto"); const alice = crypto.createDiffieHellman(512); const aliceKey = ...
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Intercepting messeges in attacks on authentication protocols

I've recently read about Diffie-Hellman Man-in-the-Middle attack when a third party can intercept messages and thus construt two different symetric keys with both sides. However I still don't ...
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Which algorithm is used to combine a key between client and server?

I read a lot of Q&A here, and read a lot of articles about RSA and Diffie-Hellman, but it seems like they are all saying opposite things about the question: When I start an HTTPS session in a ...
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How to decrypt Diffie-Hellman in wireshark?

How can i decrypt Diffie-hellman TCP packets? I'm trying to make a tool that shows cleartext response from a server that uses this encryption. However when i look online people all seem to say it's ...
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Do I need an ECDSA SSL certificate to use Diffie–Hellman key exchange method?

I cannot quite understand the role of Diffie–Hellman key exchange. Does RSA SSL certificate work with the Diffie–Hellman key exchange or is it only used with an ECDSA certificate? When is Diffie–...
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ECDH_SHA2_NISTP256 (KEX) Algorithm in SSH - Vulnerabilities?

My organization within my company uses this KEX Algorithm in our SSH Implementation. Another organization within my company won't connect to our servers as long as this algorithm is implemented as ...
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In which sense is Perfect Forward Secrecy perfect? [duplicate]

Wikipedia states that Perfect Forward Secrecy "is a feature of specific key agreement protocols that gives assurances that session keys will not be compromised even if the private key of the server is ...
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When does chrome generate the prime number for TLS communication?

In a TLS handshake using DH to negotiate a session key, a prime number on both sides must exist. Calculating a prime number large enough to be secure takes a litte computational time. When does ...
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Using Diffie-Hellman exchange on low power IoT devices

I have almost 0 knowledge of IoT, their protocols and usual device constraints. I had a discussion today with someone that has a fair amount of IoT experience and we were discussing some security ...
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DH cipher suites and DH OpenSSL Generated

I need a openssl generated diffie-hellman params for work with ECDHE or DHE cipher suites on TLSv1.2 nginx server?
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Why is the Diffie-Hellmann exchange not enough to authenticate the communication partners in IKE_SA_INIT?

The IKE_SA_INIT does create a key seed SKEYSEED from the Diffie-Hellman values and nonces. Since the exchange does sharing the secret between the communication partners, I do not understand why it is ...
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Command to check a website is vulnerable to Logjam

I am referring this post https://www.openssl.org/blog/blog/2015/05/20/logjam-freak-upcoming-changes/ and trying to see a website is vulnerable to Logjam or not. I try with www.google.com:443 but I am ...
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Is there any way to send data securely from multiple As to B in the presence of eavesdropper, without losing anonymity like in a public key exchange?

Suppose I have n subordinates at work. Any subordinate should be able to submit his or her report anonymously to me via digital means. Also suppose that I have no means of broadcasting any form of ...
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Is there a benefit to Diffie-Hellman parameter rotation?

When setting up a web server with TLS support I've generated my dhparams with openssl dhparam -C 2048 some.pem. I understand that the output in some.pem are the parameters by which DH key exchange ...
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ECDSA ECDH Man In The Middle Attack

We have a long-term key used for signing/verifying the ephemeral keys. The problem is we have to first share the long term public key with the other party. Is it possible to avoid a man in the middle ...
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Is client-side password hashing still useful when using TLS? Is TLS crackable? What about PFS? [duplicate]

Is client-side password hashing still necessary / useful when using TLS? What about TLS protocols with PFS (perfect forward secrecy) like Diffie-Hellman? Let’s say that I’m running a web application ...
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Why do predefined FFDHE parameters containt '///////////'?

Recently, Mozilla published a new and excellent version of its SSL Configuration Generator. One of the changes compared to previous versions was to use predefined FFDHE (Finite Field Diffie-Hellman ...
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Diffie–Hellman key exchange questions [closed]

at the moment I am working on a chat application, where more than two clients can communicate at the same time. I just got started with the encryption so please be bear with me. My goal is to ...
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how are symmetric keys generated in TLS [duplicate]

My confusion stems from reading that TLS handshake uses some kind of Diffie Hellmann, when I was certain that the symmetric key was generated by a digest of earlier packets encrypted with clients ...
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How to decrypt Diffie-Hellman encryption in WebRTC?

I have installed a WebRTC server application, which is designed for Contact Center solutions: communicates with internal PCs in pure RTP (agents), and with external PCs (customers) using encrypted ...
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TLS-Handshake, Server Key Exchange, Diffie-Hellman: Where does key length come from?

Where does the key length come from? In this example it is 2048 bits long: Secure Sockets Layer TLSv1.2 Record Layer: Handshake Protocol: Server Key Exchange Content Type: Handshake (22)...
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Self-signed certificates and ephemeral Diffie–Hellman key exchange protocol

If we use a self-signed certificate, is ephemeral Diffie–Hellman key exchange protocol vulnerable to a man in the middle attack?
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Diffie-Hellman with non-prime modulus

When using the Diffie-Hellman key-exchange, it is said to be important to use a safe prime. However, if a non-prime modulus with sufficient bit-length is generated, is there an attack that can be used ...
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Public key encryption confusion

I'm learning Linux, and currently SSH. But there are details that I don't really understand. I've seen and understood how Diffie-Hellman key exchanges work from a mathematical point of view, but what ...
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How to find the DH prime value (if 1024 or 2048) from Internet?

I have to ensure that the server when communicating on the Internet needs to have DH prime value of 2048 bits or greater. I can find out the cipher suites that are used but cannot derive the DH ...
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OpenSSL - 2040 bit temporary key size, 2048 bit private key

Recently, I had an OpenVAS scan report that a TLS connection to Postfix used a temporary key size of 2040 bits, instead of the 2048 bits that I have set for my key size, and I have perfect forward ...
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Perfect forward secrecy in Instant Messaging with multiple devices

I have read multiple sites online about PFS and DH but I still have a few questions. I understand that in order to have PFS you must use different keys to encrypt messages. So your IM client could be ...

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