WolfSSL

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]

wolfSSL

Developer(s)	Todd Ouska
Initial release	February 19, 2006 (2006-02-19)[1]
Stable release	5.7.4[2]  / 24 October 2024
Repository	github.com/wolfssl/wolfssl
Written in	C
Operating system	Multi-platform
Type	Cryptography library
License	GPL-2.0-or-later or proprietary[3]
Website	www.wolfssl.com

Platforms

wolfSSL is currently available for Microsoft Windows, Linux, macOS, Solaris, ESP32, ESP8266, Threadx, VxWorks, FreeBSD, NetBSD, OpenBSD, embedded Linux, Yocto Project, OpenEmbedded, WinCE, Haiku, OpenWrt, iPhone, Android, Wii, and GameCube through DevKitPro support, QNX, MontaVista, Tron variants, NonStop OS, OpenCL, Micrium's MicroC/OS-II, FreeRTOS, SafeRTOS, Freescale MQX, Nucleus, TinyOS, TI-RTOS, HP-UX, uTasker, uT-kernel, embOS, INtime, mbed, RIOT, CMSIS-RTOS, FROSTED, Green Hills INTEGRITY, Keil RTX, TOPPERS, PetaLinux, Apache Mynewt, and PikeOS.^[6]

History

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]

Protocols

Main article: Transport Layer Security

The wolfSSL lightweight SSL library implements the following protocols:^[11]

• SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2, TLS 1.3
• DTLS 1.0, DTLS 1.2, DTLS 1.3
• Extensions: Server Name Indication (SNI), Maximum Fragment Length, Truncated HMAC, Application Layer Protocol Negotiation (ALPN), Extended Master Secret
• Ciphersuites: TLS Secure Remote Password, TLS Pre-Shared Key
• Post-quantum cryptography: ML-DSA added to sigAlgs, ML-KEM added to Supported Groups, QSH (deprecated and removed)
• Public Key Cryptography Standards:
  • PKCS #1 - RSA Cryptography
  • PKCS #3 - Diffie-Hellman Key Agreement
  • PKCS #5 - Password-Based Encryption
  • PKCS #7 - Cryptographic Message Syntax (CMS)
  • PKCS #8 - Private-Key Information Syntax
  • PKCS #9 - Selected Attribute Types
  • PKCS #10 - Certificate signing request (CSR)
  • PKCS #11 - Cryptographic Token Interface
  • 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

By default, wolfSSL uses the cryptographic services provided by wolfCrypt.^[13] wolfCrypt Provides RSA, ECC, DSS, Diffie–Hellman, EDH, NTRU (deprecated and removed), DES, Triple DES, AES (CBC, CTR, CCM, GCM), Camellia, IDEA, ARC4, HC-128, ChaCha20, MD2, MD4, MD5, SHA-1, SHA-2, SHA-3, BLAKE2, RIPEMD-160, Poly1305, Random Number Generation, Large Integer support, base 16/64 encoding/decoding, and post-quantum cryptographic algorithms: ML-KEM (certified under FIPS 203) and ML-DSA (certified under FIPS 204).

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.

Hardware Integration

Secure Element Support

wolfSSL supports the following Secure Elements:

• STMicroelectronics STSAFE
• Microchip CryptoAuthentication ATECC508A
• NXP EdgeLock SE050 Secure Element

Technology Support

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.

AES cipher modes

Device	AES-GCM	AES-CCM	AES-CBC	AES-ECB	AES-CTR
Intel AES-NI (Xeon and Core processor families)	All	All	All	All	All
Freescale Cryptographic Accelerator and Assurance Module (CAAM)		All	All	All	All
Freescale Coldfire SEC (NXP MCF547X and MCF548X)			All
Freescale Kinetis MMCAU K50, K60, K70, and K80 (ARM Cortex-M4 core)	All	All	All	All
STMicroelectronics STM32 F1, F2, F4, L1, W Series (ARM Cortex - M3/M4)			All		All
Cavium NITROX (III/V PX processors)			All
Microchip PIC32 MX/MZ (Embedded Connectivity)	All		All		All
Texas Instruments TM4C1294 (ARM Cortex-M4F)	All	All	All	All	All
Nordic NRF51 Archived 2018-06-19 at the Wayback Machine (Series SoC family, 32-bit ARM Cortex M0 processor core)				128-bit
ARMv8	All		All		All
Intel QuickAssist Technology	All		All
Freescale NXP LTC	All	All	All	All	All
Xilinx Zynq UltraScale+	256-bit
Renesas RX65N (R5F565NEHDFB)	All		All
Renesas RX72N (RTK5RX72N0C00000BJ)	All		All
Renesas RX MPU (R5F571MLDDFC)	All		All
Renesas Synergy DK-S7G2			128-bit

- "All" denotes 128, 192, and 256-bit supported block sizes

DES/3DES cipher modes

Device	DES-CBC	DES-ECB	3DES-CBC
Freescale Coldfire SEC (NXP MCF547X and MCF548X)	64 bit		192 bit
Freescale Kinetis MMCAU K50, K60, K70, and K80 (ARM Cortex-M4 core)	64 bit		192 bit
STMicroelectronics STM32 F1, F2, F4, L1, W Series (ARM Cortex - M3/M4)	64 bit	64 bit (encrypt)	192 bit
Cavium NITROX (III/V PX processors)	192 bit
Microchip PIC32 MX/MZ (Embedded Connectivity)	64 bit		192 bit
Texas Instruments TM4C1294 (ARM Cortex-M4F)	64 bit		192 bit

Stream ciphers

Device	RC4	ChaCha20
AVX1/AVX2 (Intel and AMD x86)		Supported
Cavium NITROX (III/V PX processors)	2048 bit max.

Hashing algorithm support

Device	MD5	SHA1	SHA2	SHA-256	SHA-384	SHA-512
AVX1/AVX2 (Intel and AMD x86)				Supported	Supported	Supported
Freescale Kinetis MMCAU K50, K60, K70, and K80 (ARM Cortex-M4 core)	Supported	Supported		Supported
STMicroelectronics STM32 F1, F2, F4, L1, W Series (ARM Cortex - M3/M4)	Supported	Supported
Microchip PIC32 MX/MZ (Embedded Connectivity)	Supported	Supported		Supported
ARMv8				Supported
Intel QuickAssist Technology	Supported	Supported	Supported
Freescale NXP LTC		Supported		Supported
Xilinx Zynq UltraScale+					Supported
Renesas Synergy DK-S7G2		Supported		Supported
Renesas RX65N (R5F565NEHDFB)				Supported		Supported
Renesas RX72N (RTK5RX72N0C00000BJ)	Supported			Supported		Supported
Renesas RX MPU (R5F571MLDDFC)				Supported	Supported	Supported

Key operations: generation and exchange, elliptic curve cryptography

Device	RSA	ECC	ECC-DHE	X25519	Ed25519
Cavium NITROX (III/V PX processors)	512–4096 bit	NIST Prime 192, 224, 256, 384, 521
Microchip/Atmel ATECC508A (compatible with any MPU or MCU including: Atmel SMART and AVR MCUs)		256 bit (NIST-P256)
Intel QuickAssist Technology	512–4096 bit	128, 256 bit
Freescale NXP LTC	512 - 4096 bit	128, 256 bit	128, 256 bit	256 bit	256 bit
Xilinx Zynq UltraScale+	2048–4096 bit

MAC algorithms

Device	HMAC-MD5	HMAC-SHA1	HMAC-SHA2	HMAC-SHA256	SHA-3	Poly1305
AVX1/AVX2 (Intel and AMD x86)						Supported
Cavium NITROX (III/V PX processors)	Supported	Supported		Supported	Supported
Microchip PIC32 MX/MZ (Embedded Connectivity)	Supported	Supported		Supported
Intel QuickAssist Technology		Supported	Supported
Renesas RX65N (R5F565NEHDFB)	Supported			Supported
Renesas RX72N (RTK5RX72N0C00000BJ)
Renesas RX MPU (R5F571MLDDFC)	Supported			Supported
Renesas Synergy DK-S7G2				Supported

Random number generation

Device	RNG
STMicroelectronics STM32 F1, F2, F4, L1, W Series (ARM Cortex - M3/M4)	Supported
Cavium NITROX (III/V PX processors)	Supported
Nordic NRF51 Archived 2018-06-19 at the Wayback Machine (Series SoC family, 32-bit ARM Cortex M0 processor core)	Supported

Certifications

wolfSSL supports the following certifications:

• Federal Information Processing Standards (FIPS 140)
  • FIPS 140-2 and FIPS 140-3^[17]
    • wolfCrypt FIPS Module: 3.6.0 (NIST certificate #2425) - Historical
    • wolfCrypt FIPS Module: 4.0 (NIST certificate #3389) - Historical
    • wolfCrypt FIPS Module: v5.2.1 (NIST certificate #4718) - Active
• Radio Technical Commission for Aeronautics (RTCA)
  • DO-178C
    • 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.

See also

• Free and open-source software portal

• Transport Layer Security
• Comparison of TLS implementations
• Comparison of cryptography libraries
• GnuTLS
• Network Security Services
• OpenSSL

References

1. "wolfSSL ChangeLog".
2. "Release 5.7.4". 24 October 2024.
3. "LICENSING". GitHub.
4. wolfSSL – Embedded Communications Products
5. "What You Need to Know About the TLS 1.3 Protocol and wolfSSL's SSL/TLS Libraries". www.allaboutcircuits.com. Retrieved 2018-12-28.
6. "wolfSSL Embedded SSL/TLS Library | wolfSSL Products". Retrieved 2019-01-31.
7. OpenSSL: Source, License
8. wolfSSL – License
9. "MySQL, Building MySQL with Support for Secure Connections". Archived from the original on 2017-07-06. Retrieved 2016-06-12.
10. Daniel Stenberg, founder and Chief Architect of cURL, joins wolfSSL
11. wolfSSL – Docs | CyaSSL Manual – Chapter 4 (Features)
12. "wolfSSL 3.6.6 is Now Available".
13. wolfSSL – Docs | wolfSSL Manual – Chapter 10 (wolfCrypt Usage Reference)
14. Kerberos: The Network Authentication Protocol
15. NTRU CryptoLabs Archived 2013-02-02 at archive.today
16. wolfSSL – wolfSSL with Intel® SGX
17. WOLFCRYPT FIPS 140-2 and FIPS 140-3
18. wolfSSL Support for DO-178C DAL A

External links

• wolfSSL/CyaSSL Homepage
• wolfSSL Now With ChaCha20 and Poly1305