I will need to distribute a file to people for a challenge and I need them to open the file at the same time. The file will be provided a couple of days before the challenge. For maximum compatibility (so no need for 3rd party software, just OS supplied tools) I was thinking of using a password protected Zip 2.0 file.
After some reading I think this will be OK, but I'm not sure. I can't seem to find information on my specific use case (the file only needs to be secret for a short amount of time).
There will be only one file and I will use a 5 word diceware password to make it easy for entering the password while keeping quite a bit of enthropy.
Will this keep my file secure for about a week, assuming people don't have access to big computing clusters?