Idiot code

A code whereupon the 'syntax' or 'rules' of communication are worked out between the parties.

Example: Any sentence where 'day' and 'night' are used means 'attack'. The location mentioned in the following sentence specifies the location to be attacked.

Message from person1 to person2: We walked day and night through the streets but couldn't find it! Tomorrow we'll head onto Rome.

The only way to break this code is to: A) Know what the words/phrases/rules are ... OR ... B) To see enough of the messages to work out the 'rules'

The problem with A is that this type of information passing is set up before usage and is extremely hard to decipher as the message is 'hidden' in 'plain sight'. You would not even know it is a communication.

The problem with B is that you would need several 'verified' messages of this type to determine the rules of communication.

The drawbacks of this type of message passing is that is it extremely limited. A 'codebook' would be needed to effectively communicate complex information. Simple information such as 'yes' or 'no' can be built into to phrases and have several varients. However, complex information such as 'Meet a man with red hair under the Bass Bridge at 12:43 and be sure to wear a black cloak and a fedora so he recognises you' would be much harder.. unless you have constructed your 'rules' to allow for this type of information to be passed.

This type of communication is akin to the hand signals used by armies in the field.