Adaptive Echo

Adaptive Echo allows auxiliary nodes to direct data via pseudo-private
tokens. Buzz data is not directed.

Please consider the following examples.

Example #1

Let A, B, C, and D be server nodes and let a, b, c, and d be four
client nodes.

Suppose the network topology is as follows (a drawing will help):

a - A - B - b
B - C - c
C - D - d

Let t_B_1 and t_B_2 be two tokens that B is aware of.

Suppose none of the private nodes know the tokens. If so, all echo
communications will behave as they would do without Adaptive Echo.

Now suppose that node a and node d know t_B_1. As B begins to receive echo
data from A and C, it will become aware that A and C are aware of t_B_1.
Once it establishes this knowledge, it will direct traffic having special
signatures from A to C and from C to A. Until node b provides a special
signature, it will not receive data from either A or C if that data includes
the special signature. Although nodes b and c do not know t_B_1, they will be
able to communicate via B.

Example #2

Let S, a, and e be client and server nodes. Let b, c, d, and f be client
nodes. Let d be a server node. Suppose S, a, c, and f are aware of
the secret token t_1.

The network topology is as follows (again, a drawing will help):

f - e - a - S
d - S
b - S
c - S

If f transmits a message intended for d, d will receive the message via S
because S connects to d.
