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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Key-exchange over the network with more than two peers

Me and my team is developing a multiplayer videogame with a Client/Server-Topology. This secures the match from clients who have the intention to cheat because of server authority but still allows the ...
0
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0answers
16 views

How does BB84 fare against an attacker who can entangle qubits? [migrated]

Consider the following attack on the BB84 quantum key exchange protocol (as far as I can tell, it should work similarly for E91): After Alice sends her key bits encoded in qubits with randomly chosen ...
2
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1answer
47 views

Can a user verify the quality/safety of pregenerated SSH moduli parameters?

Many tutorials about how to mitigate the Logjam recommend regenerating Diffie-Hellman moduli. This is a resource intensive operation, especially for high-bit groups. This made me think if it made ...
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0answers
20 views

Key Distribution Center Key Protocol Analysis

http://i68.tinypic.com/fwu92v.png As shown in the image, why is Circle 1 to be B and Circle 2 to be A? Why is not the opposite, that is, Circle 1 to be A and Circle 2 to be B? like this picture ...
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1answer
53 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? ...
3
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1answer
70 views

OpenSSL's EVP functions, more specifically EVP_SealInit

Reference: https://wiki.openssl.org/index.php/Manual:EVP_SealInit%283%29 I want to securely share a symmetrical key between two endpoints using OpenSSL's EVP interface. Transferring the encrypted ...
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1answer
31 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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2answers
46 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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1answer
72 views

Could Diffie-Hellman be used to stop people who knows the PSK from snooping on your WiFi?

One known problem with WPA2 is that anybody who knows the preshared key can snoop on the handshake and decrypt all subsequent traffic between any parties on the network. In the typical coffee shop ...
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0answers
115 views

Secure Handshake and register for Auth

The registration The Start - pre-authentication Let's assume there are Alice and Bob. They know each others public keys and each of them generates a random string - Bob's Bobkey and Alice's Alicekey....
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1answer
152 views

Wireshark SSL stripping

well this question could be asked in Wireshark forums or Stackoverflow forums but, I think the question invloves development and security factors as well so i find the Information Security forum is ...
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2answers
9k views

Client-server encryption technique explanation (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 128 bit keys)

I opened a web page using https. When I looked at the page info provided by my browser (Firefox) I saw following: Connection encrypted: High-grade Encryption (...
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0answers
60 views

Diffie Hellman Key Exchange in a messaging application

I'm currently a student that is trying to develop a messaging application on android using java that will implement diffie hellman key exchange in order to ensure that they both will be able to ...
0
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0answers
38 views

Preventing a key from being found by analysis

Lets say Alice wants to send an encrypted message to Bob. They both know a secret key. Alice uses the key to encrypt the message and Bob uses the key to decrypt the message. Now, if the handshake ...
0
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1answer
110 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 ...
0
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1answer
55 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?
1
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1answer
32 views

Is there a secure method of distributing keys to network-booted diskless nodes?

I have a bit of an 'initial trust' issue. We are using CoreOS to run Kubernetes, and secure both the etcd API and the Kubernetes API servers using client certificates. We are using iPXE to boot ...
2
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2answers
42 views

Why is random DH group recommended over a standard group?

I know in light of logjam there have been recommendations to generate your own DH group (https://weakdh.org/sysadmin.html). It seems to me that leaving this task up to the end user is much more likely ...
1
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1answer
59 views

How to test TLS handshake process?

I need to test the handshake process of TLS. I thought to use inter-process communication in Linux. Is it possible or not? If not, what simulator could be used for this purpose? If yes, what do I ...
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0answers
59 views

Key Hierarchy and key Encryption

If i have two 56-bit DES keys, and I use these two key to encrypt a 256-bit AES key. Like this: K_AT encrypts K_BT and K_BT encrypts K What is the effective security of key K? Is it 2 X 56 Bits?
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0answers
26 views

key hierarchy management and master key

Now, I have this equation, {{K_ab}K_bs}K_as. K_ab is encrypted by K_bs then whole packet is encrypted by K_as I think the key structure is K_as is the master key, K_bs is under K_as and K_ab is the ...
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1answer
28 views

SSH session_id in RFC 4253 (key exchange)

in RFC 4253 "SSH Transport Layer Protocol", section 7.2 specifies how session encryption and integrity keys (and IVs) are derived from the shared secret (K) and the exchange hash value (H). It uses, a ...
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0answers
38 views

Migration problem between different machines using TrouSerS TPM library

My question coincides with the question posted by Maximiliano Ezequiel. Below is a question. I could make migration process work in one single machine. I can: Export SRK public key. ...
5
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2answers
145 views

Public key for SSH over the internet differs from a key for SSH over the LAN

I have a Raspberry Pi and can access it via SSH (authentication via user password) when my laptop is in the same network. Now I want to access it over the internet. I already set my router to forward ...
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2answers
3k views

How to secure API (private key) for mobile apps

I am building a web service that has to be only accessible for iOS apps. In the future I want to expand to a mobile web-site to make my service also available for other mobile operating systems. Now,...
3
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1answer
57 views

Is symmetric encryption with one time pre-shared key secure?

Suppose I have a secure channel between client and server, with proper certificate validation etc (actually, ssh session). I want to establish a secure connection between my own application on a ...
113
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6answers
77k views

“Diffie-Hellman Key Exchange” in plain English

Can someone explain to me what Diffie-Hellman Key Exchange is in plain English? I have read in a non-tech news page that Twitter has just implemented this technology which allows two persons to ...
4
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2answers
1k views

DEK, KEK and Master key - simple explanation

This article is intended to be a simplified explanation sans drill-down for people wanting to understand these concepts/terms. What are DEK, KEK and MEK/Master key?
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0answers
47 views

How rf remotes for “cloning” rolling code find matching codes?

I've been tinkering with a rf (garage door) remote control that has a scanner mode (google JMA SR-48 for details). This mode works for Mutancode and Erreka which I assume would be similar to KeeLoq. ...
5
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1answer
75 views

Is OpenSSL generating Diffie-Hellman parameters that are safe for use in TLS or SSH servers?

I would like to generate Diffie-Hellman parameters on a Debian GNU/Linux "Jessie" 8 with OpenSSL. Lets assume the system CSPRNG was seeded with some real random data. On such a system, is the result ...
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2answers
1k views

How do certificates stop this man in the middle attack?

Alice and Bob are trying to set up a secure conversation, but unknown to them in the middle is Eve, who can intercept and modify all packets sent between them. The communication goes as follows: ...
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2answers
116 views

Best encryption mechanism for message storage/exchange in client/server application

So I am building a client/server system that is similar to email idea where clients exchange messages through the server with the following main requirements (note that the clients are pre-registered ...
4
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1answer
104 views

Infinite one time pads, brute force multiple pads?

So based on my understanding using the same key for encrypting two completely random plain texts when using an otp cipher will still retain perfectly secret. This is based on the answers on this ...
3
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1answer
123 views

Security of Web Game over WebSockets?

Project that I'm working on depends on WebSockets to communicate between the server and client browser for all interactions within the game. I'm attending university for Computer Security, but I'm ...
24
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1answer
25k views

What key exchange mechanism should be used in TLS?

There are many key exchange mechanisms that can be used in TLS. Among them are RSA, ECDH_ECDSA, ECDHE_ECDSA, ECDH_RSA, ECDHE_RSA and others. Which of these are more cryptographically secure and can be ...
3
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1answer
87 views

What is the best method for key exchange?

I have application working between server and client. All messages must be encrypted and decrypted. I use AES algorithm and I want method to hide the key. I found Diffie-Hellman algorithm, but my ...
4
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2answers
286 views

Purpose of key confirmation

Among the requirements for a secure key exchange is the key confirmation. I wonder why is this step required. Even if the other party hasn't computed a correct value for the shared secret, it doesn't ...
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1answer
45 views

Is there a PAKE algorithm where the passwords can be tested in the first round?

I want to use PAKE for key exchange between two parties (Alice and Bob) which share a low entropy secret (a password they exchanged on a piece of papers). Alice and Bob use a software on there ...
5
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1answer
110 views

Is this a safe way to verify public keys?

I want to verify a public key like this: Alice generates a public/private key pair for encryption Alice generates a public/private key pair for signing Alice signs a random 4-letter word + the ...
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0answers
46 views

Can SRP be implemented using libsodium

I am using libsodium for cryptography and I want to use SRP for key exchange. The wikipedia page lists a python example, but I am not sure if and how I could convert this to libsodium function calls. ...
3
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2answers
48 views

What is the message called someone sends to verify a key?

Suppose Alice wants to check if Bob has a certain keypair. Alice could send some random payload to Bob and let Bob sign that payload with his private key. Alice is now able to check if the signature ...
0
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1answer
100 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, ...
4
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3answers
104 views

How many keys are used in this specific TLS 1.2 connection?

That shows the mechanism of the connection. How many keys are being used in this connection? What are they? Who knows them? What is the purpose of each key?
3
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2answers
159 views

Encryption in peer to peer chat

For a homework assignment I'm developing a chat service that will be able to communicate within a single network. The communication channel should be encrypted with RSA. Should I generate keypairs ...
2
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3answers
251 views

Why do I have to use multiple keys for each direction and purpose?

I'm currently writing an examen about 'Lessons Learned in the IT-Security'. I already found some thing, which shouldn't be done. But right now I'm in trouble finding the reasons why not to do so. ...
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4answers
5k views

Why is key exchange necessary at all?

Let's say "Alice" and "Bob" want to communicate with each other over an insecure network. Using Diffie–Hellman key exchange, they can get the same symmetric key at last. However, as I understand, ...
3
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2answers
108 views

3rd party requires my server's public key for a secure connection?

I'm trying to integrate with a 3rd party service and they have requested our server's public key. I've sent it to them and they said they have configured it on their end. In order for me to make ...
0
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1answer
92 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 ...
3
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1answer
661 views

Encryption key exchange for Tor

I've been studying how Tor works - including the great QA "Why can a Tor exit node decrypt data, but not the entry node?". I understand the concept of onion routing and multiple layers of encryption....
4
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2answers
259 views

Unseen.is encryption claims revisited with their proprietary, patented “xAES” algorithm

I had asked last year about the encryption claims by the web service called https://unseen.is. The very same service that had claims of "beyond army level encryption", "4096 bit keys" etc. This is the ...