spreadsheet in plain HTTP (no HTTPS)

[lesto]

Hi,
i need to collect data from a embedded device (arduino) and put it in a 
spredsheet.
I know i can use plain HTTP but without autentication and the data is lost 
in 24 hour.
How can i use autentication without HHTPS? mybe with a public spreadsheet?
hope it is possible :-)
bye