mbedtls_md5_starts(), mbedtls_md5_update() and mbedtls_md5_finish()
have been marked deprecated since mbedtls version 2.7 and may go
away in the future.
These function have been superseded by versions with a return
value. They are suffixed with "_ret". We do not actually check
return values.
Also the header "mbedtls/net.h" has been superseded by
"mbedtls/net_sockets.h".