Commanders have long been able to earn extra credits by taking short messages from one station to another. For most this is the most affordable means of sending a new design or other private data, trusting to the reputation of the pilot to deliver the message to the intended recipient.
If on the other hand, you are unable to trust the messenger there is actually now a potential solution. Quantum State Message Systems, or QMSS are widely used by powers throughout space. They are self-contained self-powered computer modules. They will only relinquish their message content if interfaced with a pre-prepared receiver module. They have a complex tamper detection mechanism which will delete the message content if the container has been opened by anyone other than the intended. They contain their own power and sensor systems and typically have a mass of just under 1000kg.
