Secure implementation of public key cryptography Reading online I've found out that for example the RSA implementation that you usually find on textook is not secure.
Where I can find some secure implementation of algorithm such as RSA, ECDH, ECDSA?

(written in C or C++ or python)
Libsodium is written/implementable in C++, C and Python. It implements lots of crypto systems, such as public key cryptography. Here is the intro in the docs: https://libsodium.gitbook.io/doc/