It would be great to have the opportunity that users/authors of spreadsheet could set a password for accessing their sheet.

Most of the time spreadsheets are used to organize stuff and they contain sensitive data, which should not be exposed to the web.

In addition to the random url, it would be great if the author of the spreadsheet could set a password on his/her own.

Delegating the auth mechanism to apache / nginx as described in #4 , #166 is only an option for the server administrator and not for the users.