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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Any Suggestion Exchanging shared key between process via port in untrusted machine (infected my malware)?

I am trying to get shared key between Firefox extension and a java program running in same machine. I am communicating both application via socket. My assumption is that malware is running in ...
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15k views

The request was aborted: Could not create SSL/TLS secure channel Exception

Let me explain my situation. I created a self-signed certificate and installed it in the Trusted Root Certification Authorities section in MMC. I then created two certificates using the self-signed ...
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389 views

Secure Encrypted Chat Protocol [duplicate]

Possible Duplicate: Is there a way to negotiate a secret between 2 parties with no prior knowledge? Imagine two clients who want to establish a secure connection over a server. Both clients have ...
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2answers
106 views

Terms for differentiating between key-exchange and public-key cryptosystem

The RSA and Diffie-Hellman protocols are part of asymmetric cryptography. But is there a word to distinguish between cryptosystem like RSA (i.e. there are two keys, one for encryption and another for ...
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3k views

Are there flaws in this simple key exchange?

I'm reviewing for a computer security exam. Here is a simple scenario: Suppose that someone suggests the following way to confirm that the two of you are both in possession of the same secret key. ...
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2answers
210 views

Obtaining the public DNSSEC root key

Is the public DNSKEY of the DNS root zone that I have to trust when validating a DNSSEC key chain usually bundled with an OS? If so where is it located under Ubuntu 15.04, Linux? What is otherwise ...
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38k views

Verifying encryption in Facebook Messenger secret conversations

I've just tried Facebook Messenger's secret conversations feature. I started a conversation with Alice on Facebook Messenger for iOS. I noticed the following in Facebook's online help, under the ...
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2answers
248 views

SSL protocol analysis

1) What is the use of Cert B in this protocol? 2) What does it prove to Alice? 3) Is it okay if we remove Cert B in this protocol? Even without Cert B, isn't the fact that Bob used his private key ...
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812 views

What are the requirements for private keys in Diffie-Hellman key exchange algorithm

Basically question is: If we have pof size 2048 what sizes for private exponents should Alice and Bob choose and why?
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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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61 views

Public key distribution through a file sharing service

Would you trust a reputedly secure file sharing service for public key distribution? In my context, I cannot use certificates. Key servers seem to require PGP/GPG formats yet I'm using Microsoft ...
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3answers
226 views

Key exchange with an untrusted party

Assume there are two parties - an agent and a server. The agent must register itself to the server by sending its identifier over the internet. And let's say we use public cryptography to encrypt ...
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1answer
70 views

Why must the master key be stronger than the session key?

If I am going to use a master key to generate a session key, the master key must be "stronger" than the session key. For instance, I should not be distributing a 128-bit AES keys with a 56-bit DES ...
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1answer
2k views

rolling code & keyless entry system [closed]

The security industry typically uses rolling code algorithms to authenticate sender & receivers in keyless entry systems, which is called RKE (ex: KeeLoq). In key-less smart key car system, The ...
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2answers
296 views

Is it safe to use a ECDSA public key as a password seed for GCM/AES?

Two peers already exchanged their ECDSA (curve secp256k1) public keys using a secure channel. They want to establish an authenticated encrypted channel between them. They will use CCM mode and with ...
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3answers
534 views

What are the MitM implications of a stolen client-side private key?

Many VoIP handsets support client-side SSL authentication for auto-provisioning. Unfortunately, some devices must be programmed with their client-side keys. (Keys generated on low-entropy devices are ...
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1answer
114 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
706 views

What's the algorithm to generate a modulus and a base for a Diffie-Hellman key exchange app?

I have a school project in which I have to write a java console application that can be used for key exchange between two people. All is fine and well, but finding good base and modulus seems to be a ...
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1answer
107 views

In Asymmetric cryptography, is the number of Private Keys limited?

My question is a bit of a leading question, because I assume that the number of Private Keys is a finite number. However, it is possible that the number is such a large number that it would ...
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1answer
850 views

How to incorporate the man-in-the-middle

I am designing a web-based back-end for an online service. The service could support web based portals and mobile apps as front end. But I am stuck on how to support third-party, i.e untrusted, web ...
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1answer
145 views

MITM protection, key distribution

I want to make sure each of my apps users only get their own data, and that nobody tampers with it or sniffs it in a MITM fashion. Encryption of everything should be the solution, right? But how do I ...
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2answers
98 views

does a public key work with all encrypted programs

let us say, I use program "x" for my e-mail security. through them I have a public key and a private key. My friend uses program "y" for their e-mail security and consequentially have a public key and ...
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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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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
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 ...
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1answer
593 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
402 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
505 views

Are Multi device usage and bots in Telegram an excuse for only ssl encryption?

Telegram's E2E encryption is not secure. See: Is Telegram E2E Still Insecure? and Is Telegram secure? Lets asume its is secure and talk about the "excuses" why E2E encryption is not always used. It ...
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1answer
96 views

Do I have the private keys to CAs installed on my browser?

Could someone please help explain the following comment from Why was the private key of the Superfish certificate so easily extractable? The main issue with private key extraction is the use of the ...
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2answers
652 views

SSL session protocol vs SSL connection protocol

Slide 8, SSL Session Protocol: Slide 10, SSL connection protocol: Firstly, in Session Protocol, there is a {S}_B, what is the function of this {S}_B? Does't it help in proving Alice's identity? Is ...
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1answer
167 views

Why doesn't my manual RSA key exchange example work?

I'm trying to "manually" compute how the premaster_secret is computed using the RSA key exchange in TLS 1.2, but can't manage to make numbers meet. I am using Scapy SSL to generate a TLS session: I ...
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1answer
868 views

OpenSSL ecparam generates same private key every time?

Currently I am trying to make my web server as secure as possible and I am testing different cipher suites on the server side, some of them using ECDHE key exchange. When generating private EC keys, ...
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1answer
315 views

Key Exchange using RSA

I'm trying to do key exchange using the following scheme. Server generates an RSA-2048 key pair and sends the public part to the client Client generates an RSA-592 key pair (I have to use RSA-592 ...
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1answer
312 views

Key-Exchange Algorithms VS Local Key Generation?

I was wondering the difference in term of Security, Computational cost and Network overhead between the use of : A Key-Exchange Algorithm (e.g. Diffie–Hellman) to set up a symmetric key. The ...
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1answer
162 views

Key Exchange algorithm to be used for REST framework

I was required to create key exchange module for custom Rest framework which supports document level security in REST requests. Framework has its own security module which allows to encrypt parameter ...
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1answer
45 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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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
129 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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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 ...
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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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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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192 views

How does “Key Transparency” work?

A few days ago, Google published Key Transparency to solve the problem of verifying the key fingerprints of e.g. your chat partners. Unfortunately, I don't really understand how Key Transparency ...
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45 views

Distribution of key by server

I have read that in asymmetric cryptography, a system admin can generate key pairs on the server. After that, the users will be given the generated key pairs and this is an efficient way of doing this ...
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1answer
297 views

Is it possible to perform one-way OTR 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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2k views

In IKE protocol; what is the PRF? [duplicate]

In IKE protocol; what is the PRF ? What is "the generation of a key based on modeled random oracle hash functions"?
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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
514 views

By mistake I used private key with `ssh -i`

Days ago, by mistake I ran $ ssh user@foo_hostmachine -i .ssh/id_rsa instead of $ ssh user@foo_hostmachine -i .ssh/id_rsa.pub Do you think that my private key has been exposed to the Internet and ...
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1answer
234 views

Check to see if public key provided is PGP/openPGP compatible

I'm still new to encryption and differences between an RSA public keys and PGP/openPGP compatible public keys. First of all, is there a difference between an RSA public key and a PGP/openPGP ...
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1answer
193 views

Theorical question on encryption methods [duplicate]

Possible Duplicate: Encryption strategies for multi users access in production systems I would like to develop a service on wich clients would connect and retrieve informations. These ...
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1answer
2k views

GPG advantages / disadvantages, is it useful or secure? [closed]

I thinking about GPG, is very widely used, but is secure? Why and where we using GPG? I found an article from 2002, but is very old.