Insights For Success

Strategy, Innovation, Leadership and Security

SSL

Understanding Perfect Forward Secrecy: The Importance of PFS in Protecting Your Data Online

GeneralEdward Kiledjian

Summary

Discover the benefits of Perfect Forward Secrecy (PFS) for protecting your online data. Learn how PFS keeps your information secure. Learn about the key exchange mechanism and ephemeral key that makes PFS possible and how it is used in protocols like TLS, SSH, and IPsec.

Article

With the increasing use of the Internet for transmitting sensitive information, security has become a critical concern for both businesses and individuals. Perfect Forward Secrecy (PFS) is one of the most vital security features that help protect our data. We will examine the importance of PFS, how it works, and what it is in this post.

Let us begin by defining PFS. PFS is a security feature that ensures an attacker cannot decrypt past data sent over a connection, even if the encryption key used was obtained.

A team of researchers at the Massachusetts Institute of Technology (MIT) first proposed PFS in the late 1990s. Among the team members were Paul Kocher, Daniel Bleichenbacher, and Bruce Schneier, who were concerned about the security of SSL (Secure Sockets Layer), which did not support PFS at the time. They recognized that, without PFS, an attacker who obtained the encryption key for a connection could decrypt the current data and any data sent over the connection in the past.

To address this issue, the team proposed an ephemeral key exchange mechanism. Each session generates a unique, temporary key, which is used only for that session and is discarded afterwards. Thus, each session will have its unique key, so if one key is compromised, it will not affect the security of previous or future sessions.

PFS is now widely used in many protocols, including TLS (Transport Layer Security), which encrypts data sent over the Internet. Besides SSH, IPsec (Internet Protocol Security) and SSH (Secure Shell) also use it.

Keywords: Perfect Forward Secrecy, PFS, encryption key, data security, key exchange mechanism, ephemeral key, SSL, TLS, SSH, IPsec, online security, data protection, MIT, encryption protocols, cyber security

The start of the end for Symantec cert trust on Google's Chrome

GeneralEdward Kiledjian

A little history

Early 2017, a security researcher (Andrew Ayer from SSLMate) discovered that three certificate authorities (Symantec Trust Network, GeoTrust Inc., and Thawte Inc), owned by Symantec, had improperly issued 108 TLS certificates. It is important to understand that these improperly issued certificates would allow a threat actor to spoof or impersonate a website that was using HTTPS.

9 of these certificates were issued without the knowledge of the domain owners. 99 were issued without proper validation of domain ownership. 

This improper issuance of certificates directly contravenes the strict (prescriptive) guidelines of the CA/Browser Forum and raised the ire of internet giants like Google, Mozilla, and Microsoft. 

These guidelines and controls underpin the entire trust model of the encrypted internet.

There is no way to verify if these certificates were ever used in the wild but we also cannot verify that they were not used. 

You can see the list of certificates here

Chrome to distrust Symantec TLS Certs

https://bugs.chromium.org/p/chromium/issues/detail?id=796230

Very quickly after this second incident was made public, the developers of the Chromium project announced their intention to distrust all Symantec issued TLS certificates. Since Chromium powers Google Chrome, the most popular browser in the world, this was a punishment for Symantec's mismanagement. So started the two-year roadmap to achieve this goal. 

You can read the blog article on the Google Security blog entitled "Chrome’s Plan to Distrust Symantec Certificates".

As you can see above, the process is broken down into 3 distinct phases:

  1. Certificates issued after December 1, 2017, from Symantec's legacy infrastructure will not be trusted
  2. Certificates issued before June 1, 2016, from Symantec's legacy infrastructure will not be trusted
  3. All certificates issued from Symantec's legacy infrastructure will not be trusted.

The first phase is rolling out with Chrome beta version 66 on March 15, 2018. Domain admins still using Symantec certs issued before June 1, 2016, are encouraged to replace them ASAP. 

The full roadmap will come to fruition with Google Chrome beta 70 (due October 16, 2018). 

In an October 2017 Symantec security blog entry, we learned that Digicert will takeover certificate updated as of December 1, 2017. 

HTTPS Everywhere helps you browse safely and securely

technologyEdward Kiledjian

Whenever you browse the web, your internet browser uses a  protocol called http. Now the secure version of this protocol is called https and head to any bank website and you’ll see them add the s to http when logging in.

Why is this important? Anytime you enter sensitive information, you want to make it as hard as possible for the “bad guys” to steal it. By using https, you encrypt the data as it swirls through the internet. It is easy to see why you should like and use this more secure protocol when logging into your bank,  facebook or webmail account.

If you want your browser to use https automatically when browsing the 1400 of the most common sites, then check out a free extension called HTTPS Everywhere by The Electronic Frontier Foundation.  It automatically changes the URL for these common sites to their secure versions automagically.

The EFF describes its protection as “HTTPS Everywhere enables the sites' HTTPS protection which can protect you against eavesdropping and tampering with the contents of the site or with the information you send to the site. Ideally, this provides some protection against an attacker learning the content of the information flowing in each direction — for instance, the text of e-mail messages you send or receive through a webmail site, the products you browse or purchase on an e-commerce site, or the particular articles you read on a reference site.”

I have this installed on every machine I use. It adds a layer of protection without having to take any additional steps.