Questions tagged [key-exchange]

For questions relating to protocols for distributing public keys, and / or establishing session keys with another party. Examples of key exchange protocols include Diffie-Hellman and IKE.

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83 views

Web developer needs customer's private key

As a non security expert, I'm looking for advice from those who are. I work with company X who have hired company Y to develop their website. Company Y needs to integrate server-side online payment ...
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Examples of SSH key exchange algorithms requiring encryption-capable host keys

In the SSH spec, Section 7.1, key exchange algorithms are distinguished based on whether they require an "encryption-capable" or a "signature-capable" host key algorithm. If I ...
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GPG Questions About Exporting Subkeys to File

GPG novice here so please bear with me. From what I understand, when you generate a keypair with GPG it will automatically create a subkey pair (sub, ssb). If I wanted to give these to another party ...
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3answers
88 views

Format for data & symmetric key exchange/storage

Is there a standard format for storing/exchanging encrypted data along with the key needed to decrypt it (data is encrypted with a single use symmetric key and the symmetric key itself is encrypted ...
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8answers
6k views

Can a large corporation make a believable promise

Say there is a secret encryption key that a third party has to handle. The third party is supposed to destroy the secret key when they are done, and tell everyone else it was destroyed and therefore ...
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8answers
5k views

How can we exchange public keys between two servers in a secure way?

I have two servers with a pair of RSA public and private keys. We do not use a CA for the internal communication yet and therefore we need to exchange keys without CA. I need to establish a trust ...
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1answer
44 views

How do SRP (and PAKE generally) protect against verifier leak

I have been reading into PAKE protocols, specifically starting with SRP RFC2945 The gist of the requirement on the server is that the server saves triplet (username, verifier (v), salt (s)) in the ...
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1answer
69 views

TPM Attestation and key exchange

I have the following problem: I have two platforms, one of them has a TPM. I need to transfer data between these two platforms, so I first determine an attestation, in order to confirm that the ...
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2answers
105 views

How to securely exchange a symmetric key over a unsecure netwrok

I need to build a project for uni where I need to transfer data securely from a client to a server. I can't use PKI structures and can't save pre-shared secrets (Imagine travelling to china and some ...
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1answer
28 views

Storage of secret key in resource-constrained sensor nodes

In sensor nodes, there arises a need to store the master secret key safely. Which is the most perfect location to store the key when the sensor nodes (such as implanted body sensor node) are highly ...
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1answer
83 views

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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34 views

Establish a symmetric key: KDF based on shared secret and random salt or key wrapping?

I am designing a basic KMS based on a simple HSM, I only have access to: AES256, SHA256, PBKDF2, HMAC (and combinations like AES256-HMAC-SHA256). The admin and the users of the system have a personal ...
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1answer
580 views

How to verify that Google's apt signing key change is not malicious?

I have an Ansible script that setup google chrome apt repo. I keep Google's signing key together with the scripts (rather than download it every time) because I think it minimizes the chance of ...
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2answers
158 views

Can I use the same truststore and keystore on the client and the server?

TL;DR: Is it possible to have both sides of a SSL/TLS connection have the same public and private key, so long as that public key is trusted by both sides? More info if helpful: I'm trying to test ...
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2answers
159 views

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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1answer
103 views

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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1answer
1k views

How can I verify Keybase's end-to-end encryption between me and a friend?

The premise of end-to-end encryption (E2EE) is that the client is secure and trustworthy, your end devices is secure and trustworthy, but the network and server need not be trusted. You've read all ...
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1answer
69 views

Thought process on Network Protocol Attack

I'm preparing for an introductory information security examination in university and this is one of the tutorial question on Network Protocol attacks. I tried (a) and came to this conclusion: Since ...
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1answer
61 views

First setup security protocols (key transfer) in not-secure environment

This question might very well be more a confirmation than anything else, but I'm breaking my head over a problem I try to solve. I hope someone can either confirm my thoughts or tell me something I'm ...
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1answer
89 views

Is this key exchange algorithm secure and valid? [closed]

I'm writing reliable UDP implementation and I want it to be secure. Also, I want to make use of elliptic curve cryptography. I don't have the proper education to really understand the math behind this ...
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1answer
79 views

Authenticate Static Public Keys

How can a static ECC public key be authenticated when being shared between the client (who has just created the static ECC public key) and the CA (Certification Authority) - who will sign and send the ...
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1answer
119 views

How can I distribute highly confidential keys for a symmetric cipher?

Say I want to exchange a key with someone for a symmetric cipher (say AES) without meeting them in person. What would be the most secure way to do this over the Internet? My first instinct would be ...
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1answer
69 views

Updating Sender-Keys and Key-Management

This question is related to an earlier question I had: Encryption on Mobile Devices - Multiparty Encryption - Key Management My situation: I have many mobile devices that want to send sensitive ...
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2answers
251 views

Is it a good idea to use asymmetric encryption for a chat application?

I am reading design documents of an internal Whats-app like chat application. Developers are planning to use asymmetric encryption to encrypt all messages. Every user will have a public/private key ...
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1answer
73 views

Can I securely share an HMAC key over a TLS connection?

In a game client/server that I'm developing, I want to allow a user to authenticate over TLS (via a REST endpoint on an HTTPS server) before dropping to an unencrypted low-latency UDP protocol. To ...
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1answer
275 views

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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1answer
84 views

Can I use HTTPS to pass a symmetric key used for encrypting TCP packets?

I am making a multiplayer game for fun and wish to keep it secure. The client is written in C# and the server in node.js with a working connection over TCP at the moment. I am new to this subject, and ...
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1answer
91 views

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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1answer
212 views

Two message key agreement and mutual authentication protocol?

I am looking for, but not finding, a published protocol that does something similar to TLS 1.3 mutual authentication, but simplified by using assumptions to reduce the chattiness of TLS. If we assume ...
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93 views

Is this Key Exchange secure?

There is a key exchange process which I am having a look at. I am aware of key exchange algorithms such as Diffie-Hellman and the like, however as there is a method to provide an initial key out-of-...
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1answer
127 views

Two-party symmetric key establishment protocol

Update: original problem description I am developing a client-server system for configuration updates. The system handles update tasks. An update task is initiated on a server; multiple clients then ...
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1answer
175 views

IKE Phase 1 /w PSK resource?

I can't seem to find a sufficiently detailed resource that describes the IKE phase 1 PSK identity authentication process. They seem to focus on differences between aggressive and main mode while ...
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1answer
222 views

Can password strength be enforced with PAKE protocols?

Can a password strength policy i.e.: must contain at-least 8 chars must contain one uppercase letter must contain one lowercase letter must contain one number Be enforced if a PAKE protocol is used, ...
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1answer
501 views

ECDH and static key encryption

It's been a while and I'm still trying to figure out if my understanding of ECC crypto is correct. Basically from what I understood a purely asymmetric encryption is never used. Usually the ...
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1answer
672 views

GPG: Is 'pubring.kbx' safe to share?

This public keyring pubring.kbx (as I merely guess from the name) must be safe to share publicly or is it not? Does it contain any sensitive information with respect to private keys? I want to back ...
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107 views

Advantage Of ECDH-RSA over RSA Ciphersuites In TLS

If ECDH-RSA is used for key exchange, this is what happens: The server has its public ECDH parameter embedded within its certificate. The client generates its public ECDH parameter, extracts the ...
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2answers
316 views

Can be used ECDH with static public key and parameters?

I have protocol required for privacy. Thus, I want to use hybrid cryptography. Base on my knowledge, ECDH is fast and secure. My system consists of 3 main components a trusted-server, client, and ...
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1answer
84 views

Key distribution from a central server [closed]

I have a system composed by different computers that must communicate in a real-time context. All the communications must be encrypted and this system is not connected to Internet, it's just a bunch ...
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2answers
352 views

TLS protocol, session key for secure connection

In Wikipedia, as part of handshaking between a client and a server, the server send a public encryption key as part of the digital certificate. Then the client uses Diffie–Hellman key exchange to ...
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1answer
99 views

Secure Key Storage

We have a security solution that is deployed on premise to companies with big technical infrastructures. We do real time vulnerability/configuration assessment of all critical assets in the network. ...
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1answer
39 views

What is this scheme called and how should it work exactly?

So I was thinking about client-server communication and how to keep this private, especially from man-in-the-middle attacks. I came up with a scheme that I'm sure exists already, but I could not find ...
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1answer
111 views

Available alternatives for exchanging public keys for emailing

What alternatives exist for exchanging public keys with another person for sending email, except the obvious way of manually pasting the public key into an email saying, "Here is my public key"? Do ...
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3answers
193 views

Sending Encryption/Decryption keys over HTTPS

I am a newbie to the cryptographic world so bear with me. Thinking of a strategy (for securing P2P data) in which server is generating a key which should be used for AES encryption between clients ...
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39 views

Any facts that users’ secret key is stolen on some group?

I am wondering whether some severe accidents due to sharing a secret key exist in real world. A group of users or a company typically share a secret key to decrypt some shared encrypted data possibly ...
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4answers
13k views

Can we trust onetimesecret?

Alice: I need the file Bob: Sure, and I want to encrypt it first. Please put the strong PGP symmetric key with the copy&paste method to https://onetimesecret.com/ and send me the link. Alice. ...
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276 views

How to perform a MITM attack on SSH exploiting the Diffie Hellman key exchange

I have an open-ended project for a class and I picked to make a tool/use existing tools and applications to exploit the Diffie-Hellman key exchange to be able to inject, modify and delete messages ...
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0answers
549 views

computing the exchange hash for ecdsa-sha2-nistp256

I am writing code for an SSH server and can not get past the Elliptic Curve Diffie-Hellman Key Exchange Reply part of the connection. The client also closes the connection and says "Host Key does not ...
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1answer
772 views

Tor: Is a diffie-helman key exchange being done over reciepient of traffic?

As I was looking over Tor specifications and I noticed that when a circuit is generated then on each circuit's node a Diffie-Hellman key exchange is being done over an encrypted path on each Node as ...
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3answers
165 views

How secure is using Saving Session Feature on WinSCP?

I ssh to my AWS instances via WinSCP and it has public-private key authentication, password authentication is disabled. All the sessions are saved on WinSCP, so I click on the IP of the machine and I ...
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908 views

Why does TLS 1.3 deprecate custom DHE groups?

According to the second draft of the TLS 1.3 specification, custom DH groups have been deprecated. As we all know, hardcoded DH groups are vulnerable to a precomputation attack that allows retroactive ...

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