Questions tagged [forward-secrecy]

Forward secrecy is a cryptographic property of a protocol ensuring that future compromise of a long-term key (e.g. private keys in TLS) will not allow the adversary to compromise the short-term (session) key and decrypt past communications. Unless the adversary uses the Man-in-the-Middle attack, past communications will be unbreakable for protocols possessing the property.

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Is forward secrecy useful for an application where keeping message history is an integral part?

I am writing a decentralized application that lets certain privileged users post messages to other users. These messages should be encrypted so that only the two of them can read it. Messages are ...
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Can an old SSH session be reconstructed given root access to the server?

Say that A is behind a firewall that logs all packets, communicating with B over a publickey-authenticated SSH connection: A <-------- {ssh} --------> B v v [...
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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 ...
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Static Key Ciphers and key persistence

A vulnerability report states the following: The server is configured to support ciphers known as static key ciphers. These ciphers don't support "Forward Secrecy". In the new specification for ...
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SSL/TLS cipher suites order for Windows 2016 hosted https sites

We are SaaS & IaaS provider that predominantly use Windows 2012 (R2) for hosting. We have started evaluating Windows 2016 OS and noticed our sites are no longer accessible via Chrome / Firefox (...
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TLS: is authentication and forward secrecy possible without PKI?

Im making a project that consist of a client/server system that requires TLS without PKI.. Design Requirements: The client MUST authenticate that it's communicating with 'THE' server The server ...
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Are Matrix messages encrypted using perfect forward secrecy?

I can not find it in the FAQ. I know, that TLS has PFS. But I am not interested in transport security but the message encryption of Matrix. Are the messages of Matrix encrypted with PFS?
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Using PFS with GnuPG?

Is it possible to use PFS with a PGP message? $ gpg2 --encrypt --armor --something? --something? -r friend@email.com PFS with GPG probably isn't possible -- otherwise everyone would be using it ...
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How to enforce Perfect Forward Secrecy using JVM properties?

According to this blogpost Perfect Forward Secrecy (PFS) is provided by: Anything on the Algorithm Standard Name list that start with TLS (Transport Level Security) followed by a type of DHE (...
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Allowing 3rd party to examine SSL/TLS traffic on servers which provide PFS

I have a question regarding the combination of CDN's & PFS configured servers. A client of mine uses Akamai's CDN services on a large scale. Most of the clients application is on Clear-text pure ...
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How to tell my HTTPS connection to a site uses PFS?

Does the browser have a UI for displaying the details about the TLS connection to the website, besides the "secure/insecure" icon?
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How does forward secrecy beat public-key encryption if the key is regularly updated?

Why is forward secrecy better (say for WhatsApp) than public-key encryption with a routinely revised key? The advertised issue is backwards safety: If at a point one key is compromised, someone ...
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Does Perfect Forward Secrecy (PFS) make Man-in-the-Middle (MitM) attacks more difficult?

Does Perfect Forward Secrecy (PFS) make Man-in-the-Middle (MitM) attacks more difficult? If not, why?
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How can I make locally stored data unreadable unless connected (logged in) to server?

I have a chat application built in Java. The chat app stores a log of the user Jimmy's chats locally on his machine. I want this chat log to be encrypted so if someone uses the computer (authorized ...
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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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Which browsers don't support Forward Secrecy and ECDHE

The question is which browsers are known not to support Forward Secrecy and the Diffie-Hellman (DHE) or Elliptic Curve cryptography (ECDHE) ciphers? We have clients who are demanding we support ...
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Is there a way of achieving perfect forward security with one directional messages?

Using for example ECDH and ephemeral keys, it is possible for two parties to establish a shared key with perfect forward security, i.e. even if the long term keys are lost, it will not be possible to ...
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nginx recommended ssl_ciphers

I am looking for some advice on setting the ciphers for nginx with SSL. What would you recommend for a good compromise between security and compatiblity at the moment? I have made some research but ...
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Forward Secrecy in TLS-PSK

I'm reading RFC4279 (Pre-Shared Key Ciphersuites for Transport Layer Security), Section 7.1, which is about Perfect Forward Secrecy. In that section, it's said that PSK/RSA_PSK ciphersuites don't ...
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Why do the banks all use weaker TLS suites? [closed]

I've been checking out various TLS certificates lately and noticed that most of the banks seem to have the following two issues: 1) They do not offer perfect forward secrecy 2) They are still using ...
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Forward Secrecy not supported with referenced browsers?

I am running a scan against one of our servers from the Qualys SSL tester site and it says that my server "does not support forward secrecy with the referenced browsers". What exactly does that mean? ...
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Instant Messaging End-to-End

I plan to create an application for secure instant messaging, now I don't know whether or not I want to implement the encryption by myself. This project is also mainly for educational purpose so I ...
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Defending against private key leaks such as those enabled by Heartbleed

More and more evidence seems to be surfacing that the Heartbleed vulnerability leaks the private key portion of the SSL certificate in use. As such this can actually mean that if an attacker was also ...
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Why don't more websites implement Perfect Forward Secrecy?

From what I understand, all it takes to enable PFS on a webserver is adding ephemeral cipher suites (ones that use DHE and ECDHE for the key exchange) to the list of cipher suites used in SSL/TLS ...
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Recommended ssl_ciphers for security, compatibility - Perfect Forward secrecy

I'm currently using nginx with the following ciphers: ssl_ciphers HIGH:!aNULL:!eNULL:!LOW:!ADH:!RC4:!3DES:!MD5:!EXP:!PSK:!SRP:!DSS; I would like to maintain compatibility to older browsers, ...
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PFS incentive during IKE Phase 2

I'm trying to see the actual point in implementing Perfect Forward Secrecy during Internet Key Exchange Phase 2, if it had already been used during Phase 1. Quoting the IKEv2 RFC: RFC 5596 3.3.2....
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Achieving PFS with public key cryptography

I'm seeking to understand how Perfect Forward Secrecy (PFS) works for non SSL applications. More specifically, I'm interested in how Moxie Marlinspike accomplishes this in TextSecure and other ...
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Emails are forwarded to wrong addresses and possible hacking?

Multiple email addresses for my domain have been compromised. My client forwarded me an old email which he sent me few days ago but I haven't received that email. That email was sent to an email ...
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Forward secrecy for kids

In the Scouts, it is popular to use secret codes to write messages (which are simple ciphers). I want to introduce Forward secrecy to the kids so they can use it with these ciphers. So, if the ...
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How common is Perfect Forward Secrecy in HTTPS clients?

We are hosting an SaaS website and API with the https protocol, both of which are accessed by numerous users with a lot of different browsers and client-side apps. What would happen if I made PFS ...
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PFS on nginx: only RC4 gets used (TLS_ECDHE_RSA_WITH_RC4_128_SHA)

I'm trying to configure my webserver for perfect forward secrecy. I'm using ssl_ciphers EECDH+ECDSA+AESGCM:EECDH+ECDSA+AESCBC:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA256:EECDH+aRSA+AESCBC:EECDH+aRSA+RC4:...