Network

The North Korean diplomatic shortwave network follows a forwarding tree structure, as they limit contacts between their stations to hops of usually no more than 5000 kilometers. Pyongyang sits at the root at the tree structure, as ultimate origin or recipient of all messages between it and embassies. Messages from Pyongyang are transmitted and relayed by North Korean embassies across the world, hop by hop along each branch of the distribution tree, until they are received by their final recipients. Messages from embassies are relayed and forwarded back to Pyongyang in the reverse way.

Embassies in the network are typically equipped with an 8-element shortwave LPDA. Stations are identified in two different ways:

• The address appears as the first byte of each packet in the DPRK-ARQ protocol, and identifies the peer station on the link - the destination of the packets rather than their source.
• The ID is used in the message headers to identify the origin or recipients of the messages. Historically they already appeared in former DPRK diplomatic transmission formats, prior to the DPRK-ARQ modem.

Station locations can be determined from signal propagation observations, direction-finding and triangulation, the presence and orientation of antennas on embassy buildings, contents of cleartext messages, and identifying information (countries, time zones, phone numbers...) mentioned in cleartext operator chatter.