Earlier this year, wolfSSL introduced the first official and fully supported wolfssl encryption library library for Arduino!
https://www.arduino.cc/reference/en/libraries/wolfssl/
Check out this Getting Started Guide:
https://www.wolfssl.com/getting-started-with-wolfssl-on-arduino/
I've been able to get TLS working with as little as 32KB RAM on the Arduino Nano 33 IoT SAMD21 (see micro blog).
Take your project to the net level by using commercial grade, industrial quality encryption software.
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 1.3, 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.