So, what’s new at wolfSSL? Take a look below to check out the most recent news, or sign up to receive weekly email notifications containing the latest news from wolfSSL. wolfSSL also has a support-specific blog page dedicated to answering some of the more commonly received support questions.

Great Article on SSL Interception Proxies and Transitive Trust

We recently found a great article on SSL/TLS interception proxies and transitive trust from Jeff Jarmoc at Dell SecureWorks. In his article, Jeff provides a brief introduction, background, and history of the SSL and TLS protocols, then dives into talking about SSL interception proxies.

Reading through the article gives insights into how and why these proxies are used in the real world and explains some of the major risks associated with their use. Although risks can range anywhere from legal exposure to an increased threat surface to a potential for decreased cipher strength, these proxies are a necessary part of many networks.

Jeff introduces a helpful test framework (linked below) for determining which (if any) vulnerabilities an SSL proxy is susceptible to. The framework is designed to be run from behind the proxy, and is as simple as visiting a web page. Following an explanation of some of these vulnerabilities, Jeff lists some of the current vulnerabilities found in existing proxy solutions today.

The wolfSSL embedded SSL library has had the ability to do SSL inspection for quite some time now, as we originally posted about it in September of 2010. If you have any questions about wolfSSL’s SSL inspection, please feel free to contact us at

Transitive Trust: SSL/TLS Interception Proxies
Proxy Test Framework:

As of March 22, 2018 at 8:57am CMT, the “Proxy Test Framework” URL does not exist – the data from the table is shown below.

Test Result
Mismatched CN


Unknown CA


Self Signed




Basic Constraints




Null Char (Must Trust CA)


Article on Security Fundamentals for Embedded Software

We recently read a good article from EE Times about security fundamentals for embedded software. This article points out that embedded software and device developers should take security precautions into consideration, as many developers assume that their applications or devices are not vulnerable to attack.

Topics covered in the article include doing a “threat analysis” to determine how attackers could attack an embedded device, things to keep in mind when developing embedded software systems, and common mistakes made by embedded developers which can easily lead to vulnerability.

Article: Security fundamentals for embedded software

GCM Encryption Mode Coming Soon to wolfSSL

A while back, we posted that the wolfSSL embedded SSL library would be getting support for Galois/Counter Mode (GCM) encryption in the near future. This is still true! If everything goes as planned, GCM support should be generally available for wolfSSL in June of this year. Specifically, GCM will be used in wolfSSL with AES and as a cipher suite for SSL.  

One of the benefits of GCM is its efficiency and performance in both hardware and software. Galois/Counter Mode (GCM) for block ciphers incorporates both CTR (counter mode) as well as a message authentication code (MAC), providing both integrity and confidentiality. It is designed for block ciphers with a block size of 128 bits and is able to take full advantage of parallel processing and pipelining. Referencing the Wikipedia article on GCM, “the key feature is that the Galois field multiplication used for authentication can be easily computed in parallel thus permitting higher throughput than the authentication algorithms that use chaining modes, like CBC.”

To learn more about the performance and security details of GCM, you can visit the Wikipedia page listed below. We expect to see GCM more widely adopted in the near future.  If you`re interested in testing AES with GCM or have any question or comments please let us know.

GCM (Wikipedia):
RFC 5288 (AES Galois Counter Mode (GCM) Cipher Suites for TLS):

Feedback Requested on wolfSSL and Qt Integration

Would you like to see the wolfSSL embedded SSL library integrated into the popular Qt framework? We’ve been throwing around the idea of adding wolfSSL support to Qt and want to hear your feedback. If wolfSSL was integrated into Qt, it would be available as a build option and alternative to using Qt with OpenSSL.

wolfSSL could provide the Qt framework with a much smaller footprint when compared to using Qt with OpenSSL. Looking at typical build sizes of both wolfSSL and OpenSSL, it is typical to see a 20X decrease in footprint size.

What do you think? Please let us know your thoughts, comments, and feedback at, or by posting in our related thread in our forums.

Qt (Wikipedia):

Article on Wireless Sensor Networks

We would like to recommend an article from EE Times that we recently read which talks about the design and challenges of wireless sensor networks. This article explains some of the challenges faced when implementing a wireless sensor network and the different architectures which can be used, including both clustered sensor architectures and layered architectures.

Sensor networks offer many advantages – they actively provide a robust, reliable, accurate, and fault tolerant network to a wide range of application areas. Applications of wireless sensor networks currently include seismic, thermal, visual, infrared, and other areas within commercial, consumer, government, and academic fields.

One of the challenges that wireless sensor networks face include a necessity for secure, low-power, resource-constrained nodes. The wolfSSL embedded SSL library is ideal for helping secure communication between such nodes because of it’s low resource (ROM/RAM) usage and easy portability to such small devices. To learn more about wolfSSL’s resource usage, you can visit the product page, here.

In the upcoming weeks, yaSSL will be releasing a case study highlighting how one of our customers is using wolfSSL to secure machine-to-machine (M2M) communication, and how wolfSSL has helped overcome some of the challenges outlined in this article. Stay tuned to our blog for updates!

Article: Building wireless M2M & IoT sensor networks: issues and challenges

Your Feedback Requested on Camellia Cipher in wolfSSL

Team yaSSL has recently been considering the addition of the Camellia block cipher to the wolfSSL embedded SSL library, and we would like to request your feedback on this addition. Do you think it would be a beneficial addition? If it was added to wolfSSL, would you be interested in using it? Because we strive to shape our SSL library around what our users want and need, we greatly value your feedback.

If you are unfamiliar with the Camellia block cipher, you can find a Wikipedia article on the cipher here:, or the Camellia cipher’s English homepage, here:

Please send any feedback to!

Team yaSSL

wolfSSL 2.0.8 is Now Available

Version 2.0.8 of the wolfSSL embedded SSL/TLS library has been released and is now available for download.  This release contains bug fixes, some feature enhancements, and is a recommended update for all users:

– A fix for malicious certificates pointed out by Remi Gacogne (thanks!) resulting in NULL pointer use.
– Respond to renegotiation attempt with no_renegoatation alert
– Add basic path support for load_verify_locations()
– Add set Temp EC-DHE key size
– Extra checks on RSA test when porting into 

To download the open source, GPLv2-licensed version of wolfSSL 2.0.8, please visit our Download Page.  If you have any questions or comments or would like more information on commercial versions of wolfSSL, please contact us at

For build instructions, a full feature list, API reference, and more, please see the wolfSSL Manual.

CyaSSL working with Nginx

Hi!  We have been asked a number of times about CyaSSL integration with the Nginx web server.  If you are not familiar with Nginx, it is a high performance, high concurrency web server that is becoming extremely popular these days.  You can learn more about Nginx at

Nginx and CyaSSL make a likely pairing because they are both lean, compact, fast, and scale well under high volumes of connections.  The big news today is that CyaSSL is now working with Nginx in the lab, and we expect it to become generally available in the near future.  At this time, we are seeking feedback from those who are particularly interested in using CyaSSL with Nginx and would like to work with us as beta testers.  Let us know what you think at

OpenSSL in Devices gets cracked when trying to “enhance” randomness

Hi!  The security world has been buzzing this week about two new sets of research into what we will call statistical key cracking.  The hack is one that we would not expect out of your average script kiddie, because it combines sophisticated scanning with mathematical prowess.  The overview story is the first link below.  The second and third links take you to the researchers previews.

We are particularly interested in the work from Nadia Heninger and her team, given that our user base is skewed towards embedded systems.

Our takeaways from this new research are high entropy seeds are vital to proper key generation.  If a high entropy device is available use it, if not, don`t try to write your own.  Connect securely to a remote server where a high entropy seed can be relayed over the SSL/TLS connection.  And don`t stir the RNG between (p) and (q) generation.  This crack is based on a low entropy seed and the stirring between (p) and (q) generation.  wolfSSL avoids this problem in two ways, by using a high entropy seed from /dev/random and by not stirring between (p) and (q) but before each (p) instead.

wolfSSL and LibSCS

wolfSSL is now available as a crypto provider for KoanLogic’s SCS library, LibSCS. SCS, a small cryptographic protocol layered on top of the HTTP cookie facility [RFC6265], allows its users to produce and consume authenticated and encrypted cookies, as opposed to usual cookies, which are un-authenticated and sent in clear text.

From the LibSCS README, “By having a non-tamperable proof of authorship attached, each SCS cookie can always be validated by the originator, making it possible for a server to handle clients` session state without the need to store it locally. In fact, an SCS enabled server could completely delegate the application state storage to the client (e.g. a web browser) and use it, in all respects, as a remote storage device. The result of the cryptographic transformations applied to state data can be used to ensure that its information authenticity and confidentiality attributes are the same as if they were stored privately on server-side.”

You can build LibSCS with wolfSSL by running the following commands. You must have KoanLogic’s makl installed on your development machine ( to build the package. See the libscs README and INSTALL files for more detailed instructions.

makl-conf –crypto=cyassl

libscs GitHub repository:

If you have any questions about wolfSSL with LibSCS, please contact KoanLogic (info@koanlogic) or yaSSL (

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