wolfSSL Embedded SSL/TLS Library

The wolfSSL embedded SSL library (formerly CyaSSL) is a lightweight SSL/TLS library written in ANSI C and targeted for embedded, RTOS, and resource-constrained environments - primarily because of its small size, speed, and feature set. It is commonly used in standard operating environments as well because of its royalty-free pricing and excellent cross platform support. wolfSSL supports industry standards up to the current TLS 1.3 and DTLS 1.2, is up to 20 times smaller than OpenSSL, and offers progressive ciphers such as ChaCha20, Curve25519, Blake2b and Post-Quantum TLS 1.3 groups. User benchmarking and feedback reports dramatically better performance when using wolfSSL over OpenSSL.

wolfSSL is powered by the wolfCrypt cryptography library. Two versions of wolfCrypt have been FIPS 140-2 validated (Certificate #2425 and certificate #3389). FIPS 140-3 validation is in progress. For additional information, visit the wolfCrypt FIPS FAQ or contact [email protected].

Why Choose wolfSSL?

There are many reasons to choose wolfSSL as your embedded, desktop, mobile, or enterprise SSL/TLS solution. Some of the top reasons include size (typical footprint sizes range from 20-100 kB), support for the newest standards (SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2, TLS 1.3, DTLS 1.0, and DTLS 1.2), current and progressive cipher support (including stream ciphers), multi-platform, royalty free, and an OpenSSL compatibility API to ease porting into existing applications which have previously used the OpenSSL package. For a complete feature list, see Chapter 4 of the wolfSSL manual.

Notes, Please Read

Note 1

wolfSSL as of 3.6.6 no longer enables SSLv3 by default. wolfSSL also no longer supports static key cipher suites with PSK, RSA, or ECDH. This means if you plan to use TLS cipher suites you must enable DH (DH is on by default), or enable ECC (ECC is on by default), or you must enable static key cipher suites with one or more of the following defines:

WOLFSSL_STATIC_DH
WOLFSSL_STATIC_RSA
WOLFSSL_STATIC_PSK

Though static key cipher suites are deprecated and will be removed from future versions of TLS. They also lower your security by removing PFS.

When compiling ssl.c, wolfSSL will now issue a compiler error if no cipher suites are available. You can remove this error by defining WOLFSSL_ALLOW_NO_SUITES in the event that you desire that, i.e., you're not using TLS cipher suites.

Note 2

wolfSSL takes a different approach to certificate verification than OpenSSL does. The default policy for the client is to verify the server, this means that if you don't load CAs to verify the server you'll get a connect error, no signer error to confirm failure (-188).

If you want to mimic OpenSSL behavior of having SSL_connect succeed even if verifying the server fails and reducing security you can do this by calling:

wolfSSL_CTX_set_verify(ctx, WOLFSSL_VERIFY_NONE, NULL);

before calling wolfSSL_new();. Though it's not recommended.

Note 3

The enum values SHA, SHA256, SHA384, SHA512 are no longer available when wolfSSL is built with --enable-opensslextra (OPENSSL_EXTRA) or with the macro NO_OLD_SHA_NAMES. These names get mapped to the OpenSSL API for a single call hash function. Instead the name WC_SHA, WC_SHA256, WC_SHA384 and WC_SHA512 should be used for the enum name.

wolfSSL Release 5.2.0 (Feb 21, 2022)

Vulnerabilities

[High] A TLS v1.3 server who requires mutual authentication can be bypassed. If a malicious client does not send the certificate_verify message a client can connect without presenting a certificate even if the server requires one. Thank you to Aina Toky Rasoamanana and Olivier Levillain of Télécom SudParis.
[High] A TLS v1.3 client attempting to authenticate a TLS v1.3 server can have its certificate check bypassed. If the sig_algo in the certificate_verify message is different than the certificate message checking may be bypassed. Thank you to Aina Toky Rasoamanana and Olivier Levillain of Télécom SudParis.

New Feature Additions

Example applications for Renesas RX72N with FreeRTOS+IoT
Renesas FSP 3.5.0 support for RA6M3
For TLS 1.3, improved checks on order of received messages.
Support for use of SHA-3 cryptography instructions available in ARMv8.2-A architecture extensions. (For Apple M1)
Support for use of SHA-512 cryptography instructions available in ARMv8.2-A architecture extensions. (For Apple M1)
Fixes for clang -Os on clang >= 12.0.0
Expose Sequence Numbers so that Linux TLS (kTLS) can be configured
Fix bug in TLSX_ALPN_ParseAndSet when using ALPN select callback.
Allow DES3 with FIPS v5-dev.
Include HMAC for deterministic ECC sign build
Add --enable-chrony configure option. This sets build options needed to build the Chrony NTP (Network Time Protocol) service.
Add support for STM32U575xx boards.
Fixes for NXP’s SE050 Ed25519/Curve25519.
TLS: Secure renegotiation info on by default for compatibility.
Inline C code version of ARM32 assembly for cryptographic algorithms available and compiling for improved performance on ARM platforms
Configure HMAC: define NO_HMAC to disable HMAC (default: enabled)
ISO-TP transport layer support added to wolfio for TLS over CAN Bus
Fix initialization bug in SiLabs AES support
Domain and IP check is only performed on leaf certificates

ARM PSA Support (Platform Security Architecture) API

Initial support added for ARM’s Platform Security Architecture (PSA) API in wolfCrypt which allows support of ARM PSA enabled devices by wolfSSL, wolfSSH, and wolfBoot and wolfCrypt FIPS.
Included algorithms: ECDSA, ECDH, HKDF, AES, SHA1, SHA256, SHA224, RNG

ECICE Updates

Support for more encryption algorithms: AES-256-CBC, AES-128-CTR, AES-256-CTR
Support for compressed public keys in messages.

Math Improvements

Improved performance of X448 and Ed448 through inlining Karatsuba in square and multiplication operations for 128-bit implementation (64-bit platforms with 128-bit type support).
SP Math C implementation: fix for corner case in curve specific implementations of Montgomery Reduction (P-256, P-384).
SP math all: assembly snippets added for ARM Thumb. Performance improvement on platform.
SP math all: ARM64/32 sp_div_word assembly snippets added to remove dependency on __udiv3.
SP C implementation: multiplication of two signed types with overflow is undefined in C. Now cast to unsigned type before multiplication is performed.
SP C implementation correctly builds when using CFLAG: -m32

OpenSSL Compatibility Layer

Added DH_get_2048_256 to compatibility layer.
wolfSSLeay_version now returns the version of wolfSSL
Added C++ exports for API’s in wolfssl/openssl/crypto.h. This allows better compatibility when building with a C++ compiler.
Fix for OpenSSL x509_NAME_hash mismatch
Implement FIPS_mode and FIPS_mode_set in the compat layer.
Fix for certreq and certgen options with openssl compatibility
wolfSSL_BIO_dump() and wolfSSL_OBJ_obj2txt() rework
Fix IV length bug in EVP AES-GCM code.
Add new ASN1_INTEGER compatibility functions.
Fix wolfSSL_PEM_X509_INFO_read with NO_FILESYSTEM

CMake Updates

Check for valid override values.
Add KEYGEN option.
Cleanup help messages.
Add options to support wolfTPM.

VisualStudio Updates

Remove deprecated VS solution
Fix VS unreachable code warning

New Algorithms and Protocols

AES-SIV (RFC 5297)
DTLS SRTP (RFC 5764), used with WebRTC to agree on profile for new real-time session keys
SipHash MAC/PRF for hash tables. Includes inline assembly for x86_64 and Aarch64.