Law Of Naval Warfare

Yes, not surprisingly, Naval warfare between 2 or more states in an armed conflict is bounded Laws.

And today was when I learn why to reveal your true self can also be said to reveal one's true colours.

In Navyspeak, colours also mean flags. And that can be the unique flag that your navy uses. According to some Law, it states that while a warship can use ruses like flying flags of other countries, the warship must at the point just before engagement on the enemy, fly the real flag. True colours.

Neat huh?

There is also this San Remo Manual (1994) that governs laws applicable in armed conflicts at sea.

There is this clause that restrict hospital ships from using secret codes. Hence hospital ships cannot use any form of encryption.

171. In order to fulfil most effectively their humanitarian mission, hospital ships should be permitted to use cryptographic equipment. The equipment shall not be used in any circumstances to transmit intelligence data nor in any other way to acquire any military advantage.

The interesting bit is this. Let's say Pulau Ubin is at war with Pulau Tekong. Pulau Tekong's hospital ship, for some reason, needs to communicate with Pulau Tekong warship and arrange for a rendezvous to evacuate the injured. Since no cryptographic equipment can be use, the communication between the hospital ship and warship will be in the clear (free from encryption). So all Pulau Ubin warships need to do is to listen in on the hospital ship's communications, follow the hospital ship which is heading for a rendezvous with the Pulau Tekong warship then blow the latter to smithereens.....

I am not so smart to think up that contentious example. I am not so clever. Far from it.