Is 7-Zip enough?

For example I got a document file containing nuke codes, or the outline to the next great novel series since The Lord of the Rings, or the audio files for the biggest album since Thriller, is 7-Zip enough to protect it from people who might be interested in leaking it? If I keep that 7-zip file on a hard drive, laptop, or cloud and someone got access to those, will they not be able to open the 7-zip file and …

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