I hate to say it, but if what you're communicating could risk your life or that of someone else you might want to avoid using computers to communicate it altogether.
Old-school techniques such as physically smuggling microdots[1] seem much safer than relying on any computer technology, which can always be hacked.
Old-school techniques such as physically smuggling microdots[1] seem much safer than relying on any computer technology, which can always be hacked.
[1] - https://en.wikipedia.org/wiki/Microdot