Interestingly, this is something Julian Assange worked on several year before starting Wikileaks:
Starting around 1997, he co-invented the Rubberhose deniable encryption
system, a cryptographic concept made into a software package for the Linux
operating system designed to provide plausible deniability against
rubber-hose cryptanalysis;[68] he originally intended the system to be used
"as a tool for human rights workers who needed to protect sensitive data in
the field."
