PolarSSL

PolarSSL is an open-source cryptographic library that provides Transport Layer Security (TLS) and Datagram TLS (DTLS) for embedded systems. It offers a compact, portable C implementation of TLS with support for X.509 public-key infrastructure, certificate parsing, and a set of cryptographic primitives such as RSA, ECC, AES, and hash functions. The library is designed to be easily integrated into resource-constrained environments and to be portable across a wide range of platforms and real-time operating systems (RTOS).

PolarSSL originated as a lightweight TLS library for embedded devices in the late 2000s. It gained attention for its small footprint and straightforward API. In 2015, ARM Holdings (now Arm) acquired the PolarSSL project and rebranded it as mbed TLS. Development continues under the mbed TLS project, with ongoing updates and compatibility with modern TLS features.

Implementation notes: PolarSSL is written in C, aims for portability and ease of integration, and is released under an open-source license. It provides core TLS protocol support, cryptographic algorithms, and certificate handling, with a focus on embedded and Internet of Things (IoT) use cases.

See also: mbed TLS.