# 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.

## 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.

## 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. yaSSL, alternatively, was developed and dual-licensed under both a commercial license and the GPL. yaSSL offered a more modern API, commercial style developer support and was complete with an OpenSSL compatibility layer. The first major user of wolfSSL/CyaSSL/yaSSL was MySQL. 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.

## Protocols

The wolfSSL lightweight SSL library implements the following protocols:
* 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.

## Algorithms

wolfSSL uses the following cryptography libraries:

### wolfCrypt

By default, wolfSSL uses the cryptographic services provided by wolfCrypt. 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 (where it can be enabled using a build option).

### NTRU

CyaSSL+ includes NTRU public key encryption. The addition of NTRU in CyaSSL+ was a result of the partnership between yaSSL and Security Innovation. 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) - 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
*** 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)

## 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.