Do the rules specify how an action like doubletalk (or something like it) works?
By "doubletalk", I am referring to a character conveying a message to allies while hiding that message from enemies. There are probable other words for it, as well.
An opposed Deception vs. Insight roll may be exactly what I am looking for, but I am looking for verification. Do the rules specify anywhere that Deception can be used in this way?
At this point, there are many campaign-specific books, so if the rules do exist, I suspect they are in one of the expansion books. I have not seen anything in any of the core books detailing rules for doubletalk.
The reason why I am interested:
I'm asking as a DM with NPCs attempting to use coded talk in front of the party. In the moment, it was an easy decision; I had the NPCs all understand each other, and the party could roll Insight to see if they could decipher the hidden meaning. But then the players started talking about doing the same thing, and I wanted to have some way of standardizing it for them.
Deception vs. Insight for enemies could make for an interesting mechanic if there were some additional suggestion for it.
I usually find it funny in books and movies when an ally does not get the inside joke. So, having both allies and enemies roll to see if they catch the hidden meaning could be fun. Alternately, if allies and enemies have the same DC to understand the inside joke, then doubletalk becomes as harmful as it is helpful, which makes it far less useful (and less fun). So, I am hoping to find rules that may help make this mechanic a bit more enjoyable.
Specifically, might I use different DCs for allies vs. enemies?
Do allies get automatic advantage?
Or is it just safest to allow allies to auto-succeed, and this ability is only vs. enemies?