I remember end-to-end vs. point-to-point from my crypto class back in the Pleistocene, so I thought I'd share the analogy my professor used just because I loved

I remember end-to-end vs. point-to-point from my crypto class back in the Pleistocene, so I thought I'd share the analogy my professor used just because I loved it: In WW2, the Allied Navies faced two main naval code strategies: Germany's and Japan's. Roughly, the Japanese Navy sent their routing information in plaintext, while the Kriegsmarin sent it in ciphertext. Because the German routing instructions were encrypted, each node had to be able to decrypt universally. Capture one U-boat, and, well, we all saw the movie. In contrast, the Japanese navy sent the routing information in the clear, so transceiving stations only had to read the routing information and transmit the ciphertext verbatim: capture a Japanese sub and you can only decode messages sent to that sub. However, because the routing information was visible in all transmissions, a lot of sideband avenues were opened up (you may not know what Yamamoto was sending to the Coral Sea fleet, but you're damn sure interested in the fact that he was talking to them at 2am this morning, particularly since you can then watch what they do.) Anyways, not directly relevant to the article but a cool example of how far back this question goes.