Support loading keys and certificates as variables (bytes) in particular in the load_cert_chain function

Proposal:

In MutualTLS Authentication scenarios it's useful to maintain client credential (private_key) confidentiality by allowing loading of the credential from encrypted key archives for example PKCS12. Python Cryptography and other modules allow loading of private keys into memory and at present we need to write those sensitive files to disk temporarily in order to load them into our TLS Client context.

This appears to be the existing code https://github.com/python/cpython/blob/a9c304cf020e2fa3ae78fd88359dfc808c9dd639/Modules/_ssl.c#L3899

    if (keyfile && !PyUnicode_FSConverter(keyfile, &keyfile_bytes)) {
        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
            PyErr_SetString(PyExc_TypeError,
                            "keyfile should be a valid filesystem path");
        }
        goto error;
    }

Has this already been discussed elsewhere?

There is one somewhat similar feature request relating to loading from PKCS11 tokens. This is not related.

Links to previous discussion of this feature:

No response

Comienza en Modules/_ssl.c, en la implementación de load_cert_chain y en la conversión de rutas del sistema de archivos que se muestra en el issue. Revisa cómo la función actual acepta rutas de claves y certificados y, a continuación, determina la API y la cobertura de pruebas necesarias para entradas de bytes en memoria. Se considera terminado cuando las credenciales pueden cargarse desde bytes sin requerir archivos temporales sensibles.