You're talking about sleepers, who are human beings. A message for them is just encoded. Either they decode the message with software, or it's a subliminal message that gets received by some other part of the brain (not that I believe such a thing is actually possible, but a lot of people do).
Vs. a computer virus that runs in your computer/phone and either exfiltrates information, or spreads further.
Why make it a message a human being can see/hear?
Wouldn't it be easier to just use a back door or silent message?
You're talking about sleepers, who are human beings. A message for them is just encoded. Either they decode the message with software, or it's a subliminal message that gets received by some other part of the brain (not that I believe such a thing is actually possible, but a lot of people do).
Vs. a computer virus that runs in your computer/phone and either exfiltrates information, or spreads further.