When defining an OpenVPN connection, up to 2 keys, 2 certs and one dh are to be specified.
The information is stored in NVRAM, mostly in hex and may quickly exhaust the NVRAM available.
As far as I understand, the info stored there is used to generate the configuration, key and certificate files, located in subdirectories of "/tmp/etc/openvpn".
The following would be a solution:
1) The existing input field may accept the real value (as it is now)
2) Or alternatively, a file path may be given, that points to a key or cert file stored somewhere
The program must determine whether the value given is a file path or a real value. I think this is not difficult to do and implement.
A file path would use much less space in NVRAM, and in jffs space there is ample room to accommodate all the certs and keys. In case of the CA-cert, multiple paths may point to the same file for multiple connections.
I know, there may be a workaround by not using the GUI and doing the VPN-setup by scripting. But when there is a GUI, who would not like to take advantage of it?