Diffie-Hellman | Standalone Java reference implementation of Diffie Hellman | Cryptography library
kandi X-RAY | Diffie-Hellman Summary
kandi X-RAY | Diffie-Hellman Summary
The Diffie-Hellman key exchange is a simple yet so far practically impeccably unhackable method to encrypt data transported between computers. Its foundation is so easy that it can be understood by any high school student. Still it is likely to be NSA proof for a couple more decades. This is THE example for a magical mechanism called perfect forward secrecy, where two clients can safely communicate without any prior knowledge and without depending on a corruptible third authorization party. If you are familiar with Diffie-Hellman go-ahead and point out that some minor steps are necessary to fulfill the promise. If you are new to Diffie-Hellman don't hesitate to play through the wiki example yourself to get a feeling for this magic. Once the Diffie-Hellman key exchange provided both parties with a shared encryption key, it should be used with safe algorithms such as RSA 4096 bit or AES 512 bit, as recommendated by the CCC and others. Fancy 'modern' elliptic encryption algorithms don't offer much except enormous complexity and potential backdoors.
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Diffie-Hellman Examples and Code Snippets
Community Discussions
Trending Discussions on Diffie-Hellman
QUESTION
I am currently trying to connect to an AWS REST API which requires at least TLS v1.2. The documentation stats that clients must also support cipher suites with perfect forward secrecy (PFS) such as Ephemeral Diffie-Hellman (DHE) or Elliptic Curve Ephemeral Diffie-Hellman (ECDHE).
When sending a GET request using the HttpClient, the connection simply times out. I have set the TLS version explicitely to TLSv1.2 like this:
ANSWER
Answered 2022-Mar-30 at 12:52We finally found the reason for this. Windows did not have the required cypher suites enabled. We have used IISCrypto to enable the corresponding cypher suites and all is ok now.
It looks like it's possible to force .NET to TLS 1.2, even though it was not enabled on the server itself.
QUESTION
I'm using Jenkins version - 2.332.1 and i have problem with jenkins gerrit repository ssh clone. The details as follows,
ANSWER
Answered 2022-Mar-24 at 08:50On the server where the Jenkins controller is running (assuming it is the same as the one where you tested your ssh connection manually), add to the .bashrc
QUESTION
I have a playbook that is launched from AWX with machine credentials, ie. with ssh_user_A. In this playbook, i need to perform a couple of tasks with another SSH user, ie. ssh_user_B.
In terms of credentials, I have:
- machine credentials for
ssh_user_Athat are OK, I can do whatever I need - a public/private keys couple for
ssh_user_B:- the public key is present on the remote host in the
~ssh_user_B/.ssh/authorized_keysfile - if I test this public/private key with a temp machine credentials (not possible in final target) and a dummy playbook or an ad-hoc module call, it works I can do whatever I need
- the public key is present on the remote host in the
I change the SSH user in the playbook with these instructions:
...ANSWER
Answered 2022-Mar-02 at 08:54I've made a lot of tests and found the problem: by default, to connect to the target hosts, Ansible uses the smart connection plugin. In my case, the smart plugin leads to the use of the native OpenSSH.
Forcing manually the use of the paramiko connection plugin solves the problem, everything is OK (paramiko is a Python implementation of OpenSSH). Just need to add the instruction connection: paramiko at the needed level:
QUESTION
I am having a problem connecting to some Checkpoint firewalls. They run a Linux, but I cannot install any Ansible.
...ANSWER
Answered 2022-Feb-20 at 18:06According Ansible and Check Point and Getting started with Ansible and Check Point there are modules for management (Check_Point.Mgmt) available which seems all to connect over Web Services API.
In your case you could just try with the raw module according Whats the difference between ansible raw, shell and command or with ansible_network_os=vyos or nxos according Ansible Network Examples.
QUESTION
we are currently working with a cloud product that uses JSCH internally to connect to external sftp sources. Im investigating an connection reset exception that we are getting when trying to connect to azure sftp.
Using wireshark i determined that the problem occurs after we send the Client: Key Exchange Init. Establishing the same connection with filezilla we dont have this issue.
comparing the packages from jsch and filezilla i didn't see an obivious issue, but im not an expert on the ssh protocol. im gonna post both requests below if somebody could give me any pointers it would be greatly appreciated.
Request with JSCH (not working)
Request with Filezilla (working)
Response with Filezilla (working)
See below for the log output:
...ANSWER
Answered 2022-Feb-03 at 08:09i wanted to post a quick update for anybody that is having the same issue, i opened a similiar question on the microsoft q&a site and looks like it's an issue on the azure side that they are working on fixing for GA Microsoft Q&A
QUESTION
I have ec2 instance with ubuntu v20.04 and it has python v3.8.10 and pysftp 0.2.9.
I have generate .pem file from .ppk file using below command
puttygen sftp_server.ppk -O private-openssh -o sftp_server.pem
I am able to connect successfully to sftp server using command line-
...ANSWER
Answered 2022-Jan-28 at 09:18The error comes form underlying Paramiko and is discussed here:
Paramiko authentication fails with "Agreed upon 'rsa-sha2-512' pubkey algorithm" (and "unsupported public key algorithm: rsa-sha2-512" in sshd log)
Though pysftp does not expose the disabled_algorithms parameter.
You better switch to using Paramiko directly. The pysftp is abandoned project. See pysftp vs. Paramiko.
QUESTION
I have a Python 3 application running on CentOS Linux 7.7 executing SSH commands against remote hosts. It works properly but today I encountered an odd error executing a command against a "new" remote server (server based on RHEL 6.10):
encountered RSA key, expected OPENSSH key
Executing the same command from the system shell (using the same private key of course) works perfectly fine.
On the remote server I discovered in /var/log/secure that when SSH connection and commands are issued from the source server with Python (using Paramiko) sshd complains about unsupported public key algorithm:
userauth_pubkey: unsupported public key algorithm: rsa-sha2-512
Note that target servers with higher RHEL/CentOS like 7.x don't encounter the issue.
It seems like Paramiko picks/offers the wrong algorithm when negotiating with the remote server when on the contrary SSH shell performs the negotiation properly in the context of this "old" target server. How to get the Python program to work as expected?
Python code
...ANSWER
Answered 2022-Jan-13 at 14:49Imo, it's a bug in Paramiko. It does not handle correctly absence of server-sig-algs extension on the server side.
Try disabling rsa-sha2-* on Paramiko side altogether:
QUESTION
I am trying to write a bash script that runs ssh command with debug (ssh -vvv) against a specified host/hosts.
I am not trying to login to the server, but rather just trying to see what all kex, mac and ciphers does the server offer.
I did create a script to find the kex algos after negotiation using the -G option.
...ANSWER
Answered 2022-Jan-09 at 12:17Get all supported algorithms for key exchange from remote ssh-server with nmap:
QUESTION
I'm trying to find a python equivalent of this js function:
...ANSWER
Answered 2021-Dec-17 at 18:59According to the documentation of the JavaScript library the line
QUESTION
We are in the process of setting up api gateway with Lamba function behind it. The setup uses aws cognito authorizer. We have the VPC endpoint for api gateway so that is reachable through private IP.
But cognito does not support private links so we can't have the VPC endpoint for it. So this means the token issued by Cognito has to travel from https://ourdomain.auth.ap-southeast-2.amazoncognito.com to client over the internet.
Cognito documentation says following for data in transit:-
" Encryption in transit
All requests to Amazon Cognito must be made over the Transport Layer Security protocol (TLS). Clients must support Transport Layer Security (TLS) 1.0 or later. We recommend TLS 1.2 or later. Clients must also support cipher suites with perfect forward secrecy (PFS) such as Ephemeral Diffie-Hellman (DHE) or Elliptic Curve Ephemeral Diffie-Hellman (ECDHE). Most modern systems such as Java 7 and later support these modes."
According to above the token should be encrypted.
But I have following questions:
Is TLS (1.2) enforced for Cognito?
with encryption in transit being available would security best practices still dictate having Cognito available through VPC endpoint so that the token does not need to travel on internet.
if a client application is coming from on-prem environment and accessing the api then if we make it go through a proxy in AWS then will the traffic remain in AWS backbone network or still flow through internet?
ANSWER
Answered 2021-Dec-16 at 06:54Is TLS (1.2) enforced for Cognito:
Unfortunately, no. For most API calls you could use API gateway as a layer in between and enforce TLS1.2 there. However, for the AUTHORIZATION and TOKEN endpoints this does not work. Alternatively, you can enforce it for all endpoints by deploying cognito to the US regions and using the FIPS endpoints of cognito there. See https://docs.aws.amazon.com/general/latest/gr/cognito_identity.html for the available fips endpoints.
with encryption in transit being available would security best practices still dictate having Cognito available through VPC endpoint so that the token does not need to travel on internet:
That all depends on your risk apetite. For most organizations, encryption will be sufficient. However if your risk apetite is lower, you'll want extra mitigations, following the "defense in depth" best practice. Private connectivity is just one option if many you could add. Monitoring on suapicious user activity and adaptable MFA are other methods for example.
if a client application is coming from on-prem environment and accessing the api then if we make it go through a proxy in AWS then will the traffic remain in AWS backbone network or still flow through internet?
As the api endpoints are public, they will go over the internet (public ip address, so it's routed to a NAT gateway or internet gateway).
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install Diffie-Hellman
You can use Diffie-Hellman like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the Diffie-Hellman component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .
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