wolfSSL is a small, portable, embedded SSL/TLS library targeted for use by embedded systems developers. It is an open source implementation of TLS (SSL 3.0, TLS 1.0, 1.1, 1.2, 1.3, and DTLS 1.0, 1.2, and 1.3) written in the C programming language. It includes SSL/TLS client libraries and an SSL/TLS server implementation as well as support for multiple APIs, including those defined by SSL and TLS. wolfSSL also includes an OpenSSL compatibility interface with the most commonly used OpenSSL functions.[4][5]
The genesis of wolfSSL dates to 2004. OpenSSL was available at the time, and was dual licensed under the OpenSSL License and the SSLeay license.[7] yaSSL, alternatively, was developed and dual-licensed under both a commercial license and the GPL.[8] yaSSL offered a more modern API, commercial style developer support and was complete with an OpenSSL compatibility layer.[4] The first major user of wolfSSL/CyaSSL/yaSSL was MySQL.[9] Through bundling with MySQL, yaSSL has achieved extremely high distribution volumes in the millions.
In February 2019, Daniel Stenberg, the creator of cURL, was hired by the wolfSSL project to work on cURL.[10]
PKCS #12 - Certificate/Personal Information Exchange Syntax Standard
Protocol Notes:
SSL 2.0 – SSL 2.0 was deprecated (prohibited) in 2011 by RFC 6176. wolfSSL does not support it.
SSL 3.0 – SSL 3.0 was deprecated (prohibited) in 2015 by RFC 7568. In response to the POODLE attack, SSL 3.0 has been disabled by default since wolfSSL 3.6.6, but can be enabled with a compile-time option.[12]
Algorithms
wolfSSL uses the following cryptography libraries:
wolfCrypt also includes support for the recent X25519 and Ed25519 algorithms.
wolfCrypt acts as a back-end crypto implementation for several popular software packages and libraries, including MIT Kerberos[14] (where it can be enabled using a build option).
NTRU
CyaSSL+ includes NTRU[15] public key encryption. The addition of NTRU in CyaSSL+ was a result of the partnership between yaSSL and Security Innovation.[15] NTRU works well in mobile and embedded environments due to the reduced bit size needed to provide the same security as other public key systems. In addition, it's not known to be vulnerable to quantum attacks. Several cipher suites utilizing NTRU are available with CyaSSL+ including AES-256, RC4, and HC-128.
wolfSSL supports the following hardware technologies:
Intel SGX (Software Guard Extensions) [16] - Intel SGX allows a smaller attack surface and has been shown to provide a higher level of security for executing code without a significant impact on performance.
Hardware Encryption Support
The following tables list wolfSSL's support for using various devices' hardware encryption with various algorithms.
wolfCrypt COTS DO-178C certification kit (DAL A) [18]
Licensing
wolfSSL is dual licensed:
Licensed under the GPL-2.0-or-later license. This is good for GPL open source projects and evaluation.
Licensed under a commercial non-GPL license. This comes with additional support and maintenance packages and is priced at 6,000 USD per product or SKU as of 2022.
