One of the unique wolfSSL features is the ability to run wolfSSL on bare-metal without any Real-Time Operating System (RTOS). Supporting bare-metal has always been a requirement for our libraries from initial development. Having a pure C code base, no external dependencies, portable design and modular build options enables this feature and provides a tiny build size. This is a huge differentiator compared to libraries like OpenSSL that won’t even build without a POSIX layer. The build options to enable bare-metal are (–disable-filesystem –enable-singlethreaded) or (SINGLE_THREADED and NO_FILESYSTEM).
Another unique feature of wolfSSL is our support for managing and handling longer asymmetric math computations, which may have non-deterministic execution times. We achieve this by dividing the workload into smaller chunks, allowing the CPU time to perform other tasks concurrently. We call this feature non-blocking cryptography. We support it for RSA, ECC (256/384/521) and Curve25519. Our goal is to limit any blocking on an embedded target to a maximum of 1ms. We used a generic Cortex M4 at 100MHz as our reference. This functionality, for example, allows you to service real-time events while performing a TLS handshake or signature validation. We take pride in being the only open source TLS/Cryptographic library supporting this non-blocking cryptography feature.
From the caller’s perspective, non-blocking cryptography appears much like a non-blocking socket, where the API will return a FP_WOULDBLOCK status and requires being called again. This capability is supported both through the TLS API’s and wolfCrypt directly.
For additional information, please consult the related documentation links and pull request provided below:
- ECC (–enable-ecc=nonblock or WC_ECC_NONBLOCK):
- RSA (WC_RSA_NONBLOCK):
- Curve25519 (WC_X25519_NONBLOCK):
If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.