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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54 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
78 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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0answers
41 views

Is there a key exchange protocol that requires only one message? [migrated]

Say I want to exchange a secret with someone, but I only get to send one message to the other person, and then we encrypt with that secret. Diffie-Hellman and ECDH require multiple messages to be sent ...
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1answer
49 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
115 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
59 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
106 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
44 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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0answers
41 views

How ECDH Implement in Microservices

I have a problem when I want to encrypt decrypt data by use the same key in every services.I use ECDH Method to encrypt decrypt data between client and server. I have a exchangeKey service to gen Key ...
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1answer
132 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
65 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
82 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
126 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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0answers
85 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
113 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
146 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 ...
5
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1answer
150 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
246 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
412 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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0answers
80 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
175 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
76 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 ...
2
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2answers
301 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
94 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
36 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
91 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
144 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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0answers
38 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
7k 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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0answers
215 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
397 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 ...
3
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1answer
555 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 ...
2
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3answers
139 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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1answer
695 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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0answers
136 views

Is it safe to retrieve GnuPG public/secret key with fs in Node.js?

So there is a Node.js package openpgp which is available for signing documents with GPG, but it requires public/secret key. We all know putting key right into the file is dangerous and not recommend ...
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1answer
478 views

Forward secrecy with GnuPG

I'd like to know how to implement forward secrecy using GnuPG, and I presume I need some kind of authenticated key exchange. Assuming that I have the following working already: Alice and Bob have ...
2
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2answers
225 views

SSH key based login is not vulenerable to MiTM attack. Is it true?

I read somewhere that when using key based login instead of a password based login, it is not possible for a Man-in-the-Middle attack to happen. This question is not about what is being more secure: ...
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0answers
47 views

Why would be an attacker interested in whether a cryptographic key exchange protocol succeeded or not? [closed]

Why would an attacker want to know if a key exchange between two parties succeeded or failed? What are some motivations for wanting to know this?
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1answer
611 views

TLS key exchange algorithm = Certificate signing algorithm?

My bachelor thesis is about TLS and I have a basic question about the algorithms used there. If I use e.g. a sha1WithRSAEncryption signing algorithm (RFC3279) for my certificate, that means that the ...
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1answer
79 views

Is There a Whitepaper or Explanation of ECDSA somewhere? [closed]

Let's say I wanted to write an implementation of ECDSA from scratch to better understand it. I can't find a raw, non-abstract explanation anywhere. I tried tracking down the sources on the wiki ...
2
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1answer
451 views

Limit on modulus lines in OpenSSH /etc/ssh/moduli file?

I understand that OpenSSH server looks in /etc/ssh/moduli and picks a modulus at random for each Diffie-Hellman group exchange. What I am wondering is whether there is a practical limit on how many ...
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1answer
590 views

Possible MITM attacks on ECDH-RSA or ECDHE-RSA prevents

As I understood a simplified ECDH-RSA key exchange protocol works like below Alice request Bob for its ECDH public key Bob generates ECDH parameters and sign them with a CA provided RSA certificate. ...
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1answer
186 views

CECPQ1 key exchange functionality

CECPQ1 (combined elliptic Curve and Post-Quantum Cryptography Key Exchange) is a new key exhange developed by google, which combine X25519 with NewHope (elliptic Curve KE + Post-quantum KE). Google ...
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2answers
93 views

Under what circumstances is there any real security benefit in verifying public keys in signal or WhatsApp? [closed]

Encryption is good, sure. But disclosures have revealed that both iOS and Android are so owned by intelligence services that endpoint security on all supported platforms is a joke, anyway. What ...
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1answer
1k views

What's the purpose of anonymous Diffie-Hellman key exchange + verification?

I attended a lecture where a procedure for solving the problem of passive attackers being able to gain knowledge about the identities of communication partners using an authenticated Diffie-Hellman ...
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1answer
723 views

Can you identify whether a string is a RSA public key?

I am generating RSA keys with the openssl library. I have heard that it is possible to recognise the method used to encrypt a string with AES or DES but is it possible to identify whether a string is ...
2
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1answer
485 views

Can an OpenPGP primary key revoke a subkey of a subkey?

I would like to have the following setup: a main Key, saved in a hardware wallet or paper wallet. Let's call this level 1. The idea is to never have to use this key again, as a sort of last resort. ...
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1answer
399 views

Is IKE aggressive mode really less secure than main mode?

This guy argues it is not: https://www.youtube.com/watch?v=DuowFgNKAIg I really confused about this. According to him, the only purpose of main mode is to make the peers anonymous, but in order to ...
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1answer
172 views

GPG key handling with Server

I'm using a VPS as a development machine and need gpg a) for signing git commits or e-mails (using mutt on the server) and b) for decrypting f.e. encrypted dotfiles and other files. But I don't feel ...
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0answers
82 views

What is a KEA certificate and how it is used?

I'm currently studying IKE and IPsec in the context of VPN applications and I know that a X.509 certificate is used to provide server's public key to the client (and vice-versa in case of mutual ...