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In addition, wolfSSL now has a support-specific blog page dedicated to answering some of the more commonly received support questions.

wolfSSL 3.15.7 Now Available

Happy Holidays! wolfSSL release 3.15.7 is now available!

The holiday release of the wolfSSL embedded SSL/TLS library contains many feature additions, bug fixes, and improvements. Some of these changes include improved API documentation, RSA-verify-only and RSA-public-key-operations-only builds, and several new port additions. More details about what is included with the new version of wolfSSL are listed below.

  • New Feature Additions And Ports:
  • Support for Espressif ESP-IDF development framework
  • PKCS#7 support for generating and verify bundles using a detached signature.
  • Port update for Micrium uC/OS-III
  • Feature to adjust max fragment size post handshake when compiled with the macro WOLFSSL_ALLOW_MAX_FRAGMENT_ADJUST
  • The addition of multiple languages in wolfSSL’s bundled examples can cause problems for embedded devices that can not handle the special characters. Having NO_MULTIBYTE_PRINT defined compiles out code used for printing the special characters.
  • RSA verify only (--enable-rsavfy) and RSA public only (--enable-rsapub) builds added. These are builds that can be used with --enable-cryptonly that compile out portions of RSA code. Giving the option for an even smaller build of wolfSSL in the case that only RSA public key operations or only RSA verify operations are needed.

One of the many new exciting updates to existing wolfSSL features was the support for the Intel QuickAssist v1.7 driver being added! This enables wolfSSL to be used in asynchronous mode with newer Intel hardware for a massive performance gain over the previous driver. In addition to the driver update, support for RSA key generation and SHA-3 support was added to the wolfSSL QuickAssist port. The following is a list of some of the other notable additional updates and fixes in the release:

  • Fix for Xcode build with iPhone simulator on i386
  • Fix for building the wolfSSL library with AES-CBC disabled and the opensslextra compatibility layer enabled
  • Updates to sniffer for showing session information and handling split messages across records
  • Updates for Doxygen documentation, including PKCS#11 API and more
  • Enhancements to test cases for increased code coverage
  • Updates to VxWorks port for use with Mongoose, including updates to the OpenSSL compatibility layer
  • Updating --enable-armasm build for ease of use with autotools
  • Lots of improvements were made for ease of use with Yocto. The INSTALL file bundled with wolfSSL has been updated as part of this to help guide users through a Yocto build of wolfSSL.

Some updates and minor fixes were made to the TLS 1.3 code in wolfSSL. Keeping our industry leading TLS 1.3 implementation robust and up to date. These fixes included:

  • Updates to internal code checking TLS 1.3 version with a connection
  • Removing unnecessary extended master secret from ServerHello if using TLS 1.3
  • Fix for TLS v1.3 HelloRetryRequest to be sent immediately and not grouped

This release of wolfSSL also included a fix for 1 security vulnerability. It was a medium level fix for a potential cache attack with a variant of Bleichenbacher’s attack. Earlier versions of wolfSSL leaked PKCS #1 v1.5 padding information during private key decryption that could lead to a potential padding oracle attack. It is recommended that users update to the latest version of wolfSSL if they have RSA cipher suites enabled and have the potential for malicious software to be ran on the same system that is performing RSA operations. Users that have only ECC cipher suites enabled and are not performing RSA PKCS #1 v1.5 Decryption operations are not vulnerable. Users with TLS 1.3-only connections are not vulnerable to this attack. Thanks to Eyal Ronen (Weizmann Institute), Robert Gillham (University of Adelaide), Daniel Genkin (University of Michigan), Adi Shamir (Weizmann Institute), David Wong (NCC Group), and Yuval Yarom (University of Adelaide and Data61) for the report. The paper for further reading on the attack along with more details can be found at To view or apply a patch of the changes this is the exact PR on github with the fix:


wolfSSL Yocto Project Recipe

The wolfSSL embedded SSL/TLS library is highly portable, and easy to build on many different platforms. One of these platforms includes the Yocto Project, a project that assists developers with creating Linux-based systems on any architecture.

wolfSSL also includes many recipes and projects that make it easy to build on various platforms, and is maintained in the meta-wolfssl GitHub repository. This repository contains both Yocto and OpenEmbedded recipes for wolfSSL products (wolfSSL, wolfSSH, wolfMQTT, wolfTPM) and wolfSSL example applications. It also includes .bbappend files, which can be used to configure the cURL open-source project with support with the wolfSSL library.

More information about Yocto Linux and wolfSSL can be found in the meta-wolfssl readme, located in the GitHub repository here:

For more information on using wolfSSL, please contact

wolfSSL 24×7 support

wolfSSL provides support on four levels, one of which is the 24x7 support level. This support level includes many key features not available on the others, such as an unlimited number of support incidents, around-the-clock support from dedicated members of the wolfSSL support team, and remains in effect for an entire year.

wolfSSL provides three other levels of paid support, which also include some of the same features provided by 24x7 support. More details on the wolfSSL support packages and levels can be viewed here:

wolfSSL also provides support for the latest version of the TLS protocol, TLS 1.3! Read more about wolfSSL's implementation and the protocol itself here:

For more information, please contact

TLS 1.3 combined with FIPS (#FIPS #TLS13)

wolfSSL is a lightweight TLS/SSL library that is targeted for embedded devices and systems. It has support for the TLS 1.3 protocol, which is a secure protocol for transporting data between devices and across the Internet. In addition, wolfSSL uses the wolfCrypt encryption library to handle its data encryption.

Because there is a FIPS 140-2 validated version of wolfCrypt, this means that wolfSSL not only has support for the most current version of TLS, but it also has the encryption backbone to support your FIPS 140-2 needs if required.

Some key benefits of combining TLS 1.3 with FIPS validated software include:

  1. Software becomes marketable to federal agencies - without FIPS, a federal agency is not able to use cryptographic-based software
  2. Single round trip
  3. 0-RTT (a mode that enable zero round trip time)
  4. After Server Hello, all handshake messages are encrypted.

And much more! For more information regarding the benefits of using TLS 1.3 or using the FIPS validated version of wolfCrypt, check out wolfSSL's TLS 1.3 Protocol Support and our wolfCrypt FIPS page.

FIPS 140-2 is a government validation that certifies that an encryption module has successfully passed rigorous testing and meets high encryption standards as specified by NIST. For more information or details on FIPS 140-2, it may be helpful to view this Wikipedia article:

For more details about wolfSSL, TLS 1.3, or if you have any other general inquiries please contact

To find out more about FIPS, check out the NIST FIPS publications or contact

wolfSSL Asynchronous release 3.15.7 features

Release 3.15.7 of wolfSSL Async has bug fixes and new features including:


  • All wolfSSL v3.15.7 fixes and features.
  • Fixes for additional static analysis warnings and async edge cases (
  • Added QAT v1.7 driver support including support for QAT 8970 hardware.
  • Added QAT SHA-3 support.
  • Added QAT RSA Key Generation support.
  • Added support for new usdm memory driver.
  • Added support for detecting QAT version and features.
  • Added `QAT_ENABLE_RNG` option to disable QAT TRNG/DRBG.
  • Added alternate hashing method to cache all updates (avoids using partial updates).

Here are the latest benchmarks with various build configurations:

Asymmetric ops/sec SW (CPU) SW (SP) HW QAT HW Nitrox V Symmetric MB/sec SW (CPU) SW (AESNI) HW QAT HW Nitrox V
RSA 2048 key gen 12 12 147 AES-128-CBC Enc 939 5,028 3,454 238
RSA 2048 public 10,679 118,922 271,142 140,699 AES-128-CBC Dec 926 5,585 3,464 238
RSA 2048 private 866 3,767 42,460 8,266 AES-128-GCM 22 5,517 3,341 133
DH 2048 key gen 2,915 7,559 48,931 MD5 608 3,257 2,095
DH 2048 key agree 3,026 7,477 68,351 SHA 394 1,533 2,225
ECDHE 256 agree 4,376 54,119 56,805 10,503 SHA-224 157 1,003 2,400
ECDSA 256 sign 4,153 140,668 60,038 22,165 SHA-256 152 1,003 2,401
ECDSA 256 verify 5,404 43,689 32,853 7,361 SHA-384 256 1,458 2,343
SHA-512 263 1,458 2,314
SHA3-256 742 860 2,565

Performed on an Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, 16GB RAM, 8 threads, wolfSSL v3.15.7, QuickAssist v1.7 8970 PCIe 16x OR Cavium Nitrox V CNN5560-900-C45

CPU: ./configure --enable-keygen --enable-sha3
SP/AESNI: ./configure --enable-sp --enable-sp-asm --enable-aesni --enable-intelasm --enable-intelrand --enable-keygen --enable-sha3
QAT: ./configure --with-intelqa=../QAT1.7 --enable-asynccrypt --enable-keygen --enable-sha3
Nitrox V: ./configure --with-cavium-v=../CNN55XX-SDK --enable-asynccrypt

If you are interested in evaluating the wolfSSL Asynchronous support for Intel QuickAssist or Cavium Nitrox, please email us at

wolfSSL Embedded SSL for Bare Metal and No OS Environments

Are you looking for an SSL/TLS library which will seamlessly integrate into your bare metal or No-OS environment? If so, continue reading to learn why the wolfSSL lightweight SSL library is a perfect fit for such environments.

wolfSSL has been designed with portability and ease of use in mind, allowing developers to easily integrate it into a bare metal or operating systemless environment. As a large percentage of wolfSSL users are running the library on small, embedded devices, we have added several abstraction layers which make tying wolfSSL into these types of environments an easy task.

Available abstraction layers include:

  • Custom Input/Output
  • Standard C library / Memory
  • File system (Able to use cert/key buffers instead)
  • Threading
  • Operating System

In addition to abstraction layers, we have tried to keep wolfSSL’s memory usage as low as possible. Build sizes for a complete SSL/TLS stack range from 20-100kB depending on build options, with RAM usage between 1-36kB per connection.

To learn more about how to integrate wolfSSL into your environment or get more information about reducing wolfSSL’s memory usage, please see the wolfSSL Manual or contact us directly.

wolfSSL FAQ page

The wolfSSL FAQ page can be useful for information or general questions that need need answers immediately. It covers some of the most common questions that the support team receives, along with the support team's responses. It's a great resource for questions about wolfSSL, embedded TLS, and for solutions to problems getting started with wolfSSL.

To view this page for yourself, please follow this link here.

Here is a sample list of 5 questions that the FAQ page covers:

  1. How do I build wolfSSL on ... (*NIX, Windows, Embedded device) ?
  2. How do I manage the build configuration of wolfSSL?
  3. How much Flash/RAM does wolfSSL use?
  4. How do I extract a public key from a X.509 certificate?
  5. Is it possible to use no dynamic memory with wolfSSL and/or wolfCrypt?

Have a  question that isn't on the FAQ? Feel free to email us at

wolfSSH Pseudo Terminal and Execution Feature Addition

wolfSSH is a portable embedded SSH solution developed by wolfSSL. Recently we have made an exciting new feature enhancement to allow for client side support of pseudo terminal connections. This feature can be turned on by using the configure flag --enable-term and running the example client with “-t” ( i.e. ./examples/client/client -t -h <ip> -u <username> -p <port #> ). In addition to the added enhancement of using pseudo terminals, a function was added to support console code translations from Linux to Windows terminals. This allows usage of client side wolfSSH pseudo terminals on a Windows machine when connecting to a Linux server.

Another feature that was added is the ability for sending execution commands from the client to a server. An SSH connection to execute a command can be done by using the “-c” flag with the example SSH client. (i.e. ./examples/client/client -h <ip> -u <username> -p <port #> -c <command> ) There are many use cases for this, one being the case where an embedded system wants to startup a program on another device or server and pipe input / output through the secure wolfSSH connection.

These new features can be found at the wolfSSH github repository and in the next release version of wolfSSH on the wolfSSL website here

For more information contact us at

Added wolfSSL Support for STSAFE-A100 Public Key Callbacks with TLS (#STSAFEA100)

Recently, wolfSSL released version 3.15.5 of the wolfSSL embedded SSL/TLS library. This new release features many feature additions and updates, one of which is the added support for using public key callbacks with TLS on an STSAFE-A100.

The STSAFE-A100 is a highly secure solution that acts as a secure element providing authentication and data management services to a local or remote host.  When paired with wolfSSL, this results in a robust and secure device that is able to effectively prevent external malicious attacks and provide high-strength, fast encryption.

For more information about the release or about wolfSSL, please contact

wolfSSL version 3.15.5 release notes:

wolfSSL Renesas RX e2studio Project Files (#e2studio)

Recently, wolfSSL released version 3.15.5 of the wolfSSL embedded SSL/TLS library. This new release contains various updates and feature additions to the wolfSSL library, including the addition of Renesas RX e2 studio project files.

Renesas e2 studio is a development environment based on the Eclipse IDE. It covers various building tasks (editing, compiling, linking, etc.) and also provides a debug interface. It can use a wide range of compilers, including all Renesas compilers. This tool allows developers to more easily create and manage their project on their Renesas embedded controllers.

The addition of the wolfSSL studio project files for this tool is a great game changer, as it allows developers to use the portable, low-resource use wolfSSL library. wolfSSL uses the most secure and up-to-date encryption schemes that are offered by the wolfCrypt encryption engine, and also provides support for TLS 1.3! This way, Renesas embedded controllers can use high-end encryption with the latest version of the TLS protocol.

To find out more information, please contact

wolfSSL v3.15.5 release notes:

wolfSSL STM32L4 Hardware Acceleration Support (#stm32l4)

Recently, wolfSSL released version 3.15.5 of the wolfSSL embedded SSL/TLS library. This new release features many new additions and updates, including the addition of a port for the STM32L4 MCU.

The STM32L4 is an ultra-low-power device with high flexibility, and as a member of the STM32 family, is easily integratable with the wolfSSL library. As wolfSSL is highly portable and the STM32L4 is highly flexible, if your device has any special features that interfere with the wolfSSL port, they are easily remedied.

The new wolfSSL STM32 port functionality was added into the existing STM32 port, and the STM32L4 functionality can be enabled by either defining the "WOLFSSL_STM32L4" option in the user_settings.h file, or by including the option CPPFLAGS="-DWOLFSSL_STM32L4" to the configure script if building the wolfSSL library with autotools.

Additionally, wolfSSL also provides support for the latest version of the TLS protocol, TLS 1.3! Find more information about TLS 1.3 here:

For more information, please contact



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