'Three Spies Problem'.

By node in this post we understand internet device, network of such form a graph.

Communication from node A to node B can go through other transitory node T or through
transitory nodes T₁, T₂, ... T_n.

Then we can reach node B with message with 100% success rate if transitory node(s) won't fail.

We can send messages via transitory nodes in many ways.

Let's assume we have three transitory nodes, that is - T₁, T₂ and T₃.

Then we can transmit a message:

1. Via random or predetermined node.

If that node fails, signal needs to be retransmitted.

2. Via all nodes at once, whole message.

It succeeds as long as at least one transitory node does not fail, but signal can be captured easier.

3. Via all nodes, 1/3 of message through each.

Transmission fails if at least 1 node fails. But lost part(s) of message can be resent later. There's less risk of capturing whole signal by opposing forces as well.

4. Via all nodes, 2/3 of message through each. (different 2/3 via each).

Transmission succeeds 100% of time when at least two nodes won't fail. Whole signal is captured if 2 transitory nodes are captured. When one node won't fail, 2/3 of signal are sent, then rest can be transmitted again.

When splitting signal into 2/3, whole has to be encrypted, then split into 3 parts, concatenated (joined) appropriately, then ecrypted each 2/3 again. It's difficult to decrypt message or its parts that way if one has no private keys.

For security, transmission can occur via different nodes (different internet route paths for example), and not at the same time. This can be done via three different internet cafes for example.


See also, if You wish, ... :
- 'Incoming Cipher Crisis'.