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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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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1answer
18 views

Key hierarchy structure

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
123 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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0answers
49 views

Elliptic Curve Diffie-Hellman (ECDH) Key Exchange in Plain English

Can someone please explain to me what Elliptic Curve Diffie-Hellman Key Exchange is in plain English? Similar to the top answer found here: "Diffie-Hellman Key Exchange" in plain English ...
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0answers
96 views
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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 ...
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0answers
38 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 ...
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0answers
37 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 ...
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1answer
107 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
41 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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1answer
31 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 ...
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0answers
23 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
25 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
55 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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2answers
39 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 ...
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0answers
34 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
89 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 ...
3
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1answer
55 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 ...
3
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1answer
50 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 ...
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1answer
53 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
41 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
68 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
103 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 ...
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1answer
42 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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1answer
69 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 ...
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1answer
111 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 ...
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1answer
86 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 ...
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1answer
44 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 ...
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0answers
39 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. ...
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1answer
103 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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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 ...
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1answer
82 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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2answers
125 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 ...
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3answers
98 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?
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2answers
106 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 ...
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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, ...
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1answer
87 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
82 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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2answers
241 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 ...
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1answer
111 views

Hiding both public and private keys for private communication between 2 servers

I've been trying to learn about deeper info security past abstract words like "tunnels" and "networks", and would appreciate some enlightenment on the following scenario: 2 servers are set up to ...
5
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2answers
90 views

Using plain-text phrases as public/private pair?

I'm working on an application that'll be used by relatively non tech-savvy users, and while the machines will have internet access, the app can't have any sort of hosted intermediary. The app allows ...
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2answers
51 views

ssh/scp from server to server — set permissions (no root)

I have access as a regular user (not as root) to two servers. Server A is accessible via ssh with a username and password, Server B can only be accessed using a keycard and pin. I need to set up a ...
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3answers
1k views

What to do when you can’t protect mobile app secret keys?

We have a mobile app for iOS and Android available in the Apple and Google Play stores. The app communicates with our server’s Web Services over HTTPS. We have attackers able to spoof the app ...
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1answer
111 views

Why is brute forcing DH private key harder than calculating public key?

Assuming shared parameters: prime p base g Alice's private key is a and her public key is A, which is g ^ a mod p Calcuating A requires g * g * g... a times. Modulus is applied whenever necessary. ...
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6answers
5k views

Is (safe) encryption over compromised line impossible?

I realize something like this would be the holy grail of communications security and have never heard anything to suggest it has been done. Am just wondering. A lot of mathematicians and computer ...
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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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2answers
66 views

Combinations of key exchange and signature algorithm in TLS

Let's say that one does not trust ECC a lot, and values confidentiality over authenticity (perhaps simply for the reason that MitM is more difficult than passive eavesdropping and decryption later ...
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1answer
398 views

Sharing Derived Unique Key Per Transaction (DUKPT) Base Derivation Key (BDK) with a partner

Assumptions: We have devices out in the field injected with keys derived from our one and only BDK. The devices encrypt data using the injected derived key. All our devices connect to our server ...
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5answers
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Why can't I MitM a Diffie-Hellman key exchange?

After reading the selected answer of "Diffie-Hellman Key Exchange" in plain English 5 times I can't, for the life of me, understand how it protects me from a MitM attack. Given the ...
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180 views

Security without TLS certificates

after getting an answer to Security over multi-streaming such as SCTP i have found that i do not have the capacity to give a public key or certificate to the other end securely (to be sure MitM cannot ...
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1answer
852 views

How ECDHE is signed by RSA in ECDHE_RSA cipher

About ciphers that use ECDHE as Key Exchange and RSA as Authentication: How exactly this two algorithms work together, is ECDHE process encrypted by RSA public key? What are the DH parameters? ...