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Developer(s) Todd Ouska
Initial release February 19, 2006 (2006-02-19)[1]
Stable release 3.7.0 (October 26, 2015; 23 days ago (2015-10-26)[2]) [±]
Development status Active
Written in C language
Operating system Multi-platform
Type Security library
License GNU General Public License or Commercial Distribution License
Website www.wolfssl.com/wolfSSL/Home.html

wolfSSL (formerly CyaSSL or yet another SSL) 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, and DTLS 1.0 and 1.2) written in the C language. It includes SSL/TLS client libraries and an SSL/TLS server implementation as well as support for multiple API's, including those defined by SSL and TLS. wolfSSL also includes an OpenSSL compatibility interface with the most commonly used OpenSSL functions.[3]

A predecessor of CyaSSL, yaSSL is a C++ based SSL library for embedded environments and real time operating systems with constrained resources.


wolfSSL is currently available for Win32/64, Linux, Mac OS X, Solaris, Threadx, VxWorks, FreeBSD, NetBSD, OpenBSD, embedded Linux, WinCE, Haiku, OpenWrt, iPhone, Android, Nintendo Wii and Gamecube through DevKitPro support, QNX, MontaVista, Tron variants, NonStop, OpenCL, Micrium's MicroC/OS-II, FreeRTOS, SafeRTOS, Freescale MQX, Nucleus, TinyOS, TI-RTOS, and HP-UX.


The genesis of yaSSL, or yet another SSL, dates to 2004. OpenSSL was available at the time, and was dual licensed under the OpenSSL License and the SSLeay license.[4] yaSSL, alternatively, was developed and dual-licensed under both a commercial license and the GPL.[5] yaSSL offered a more modern API, commercial style developer support and was complete with an OpenSSL compatibility layer.[3] The first major user of wolfSSL/CyaSSL/yaSSL was MySQL.[6] Through bundling with MySQL, yaSSL has achieved extremely high distribution volumes in the millions.

Today wolfSSL is used in both open source[7] and commercial[citation needed] projects. wolfSSL is included in many[citation needed] types of network devices such as smart devices on automobiles, IP phones, mobile phones, routers, printers, and credit card scanners.


The wolfSSL lightweight SSL library implements the following protocols:[8]

  • SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2
  • DTLS 1.0, DTLS 1.2

Protocol Notes:

SSL 2.0 - wolfSSL does not support SSL 2.0 as it is insecure
SSL 3.0 - wolfSSL has disabled SSL 3.0 at compile time as of wolfSSL 3.6.6


wolfSSL uses the following cryptography libraries:


By default, wolfSSL uses the cryptographic services provided by wolfCrypt.[9] wolfCrypt Provides RSA, ECC, DSS, Diffie–Hellman, EDH, NTRU, DES, Triple DES, AES (CBC, CTR, CCM, GCM), Camellia, IDEA, ARC4, HC-128, ChaCha20, MD2, MD4, MD5, SHA-1, SHA-2, BLAKE2, RIPEMD-160, Poly1305, Random Number Generation, Large Integer support, and base 16/64 encoding/decoding. An experimental cipher called Rabbit, a public domain stream cipher from the EU's eSTREAM project, is also included. Rabbit is potentially useful to those encrypting streaming media in high performance, high demand environments.

wolfCrypt also includes support for the recent Curve25519 and Ed25519 algorithms.

wolfCrypt acts as a back-end crypto implementation for several popular software packages and libraries, including MIT Kerberos[10] (where it can be enabled using a build option).


CyaSSL+ includes NTRU[11] public key encryption. The addition of NTRU in CyaSSL+ was a result of the partnership between yaSSL and Security Innovation.[11] 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 is Open Source, licensed under the GNU General Public License GPLv2.[12]


2011 Tomorrow's Technology Today - Mobile Encryption[13]

2015 Cybersecurity 500 - wolfSSL[14]

See also[edit]


External links[edit]