History Main / PublicSecretMessage

* In ''Literature/DoubleOrDie'', Bond's teacher (who is also a cryptic crossword compiler) is kidnapped. The kidnappers allow him to submit his final crossword as failure to submit it would have alerted people to the fact he was missing. He uses the crossword to conceal clues as to his location.

* In the ''Literature/YoungBond'' novel ''Literature/DoubleOrDie'', Bond's teacher (who is also a cryptic crossword compiler) is kidnapped. The kidnappers allow him to submit his final crossword as failure to submit it would have alerted people to the fact he was missing. He uses the crossword to conceal clues as to his location.

-->'''A'''ll the
-->'''T'''alk
-->'''O'''f the
-->'''M'''arket!"

* In John Twelve Hawks' (a {{pseudonym}}) ''Literature/TheFourthRealm'' trilogy, this is how the Harlequins communicate with each other and with Travelers. They leave graffiti or other notes in public places that have easily detectable second meanings decodable only by other Harlequins or Travelers.
* Creator/RobertAHeinlein's novel ''{{Literature/Friday}}''. In Vancouver, Friday is reading the personal ads in a newspaper and sees an ad that says "W.K.-Make your will. You have only a week to live. A.C.B." More than a week later she sees another ad in a Vicksburg, Mississippi newspaper that says "W.K.-Make your will. You have only ten days to live. A.C.B." Her traveling companion Georges realizes that the messages are a code -- the first message meant "number seven" (1 week = 7 days), while the second message meant "number ten".
* In ''[[Literature/GiantsSeries Giants' Star]]'' by Creator/JamesPHogan, Vic Hunt needs to send a secret message from Earth to his friend Joe Shannon on board the distant spacecraft ''Jupiter Five'', when Shannon doesn't even know to expect such a message, let alone how to decode it. Hunt sends a plaintext email that subtly directs Shannon to specific answers in that day's newspaper crossword puzzle. The original email alone means nothing, the crossword puzzle answers are just crossword puzzle answers, but when they're combined, they give Shannon instructions that lead him to the ''real'' message, which is buried in a bunch of data files also sent from Earth.

* In Creator/RobertAntonWilson's ''Literature/{{Illuminatus}}'', a secret society places personal ads reading "In thanks to St. Jude for favors answered -- A.W." as a code to their other members.

* In ''Literature/SemperMars'' by Creator/IanDouglas, after [[spoiler:[[UnitedNationsIsASuperpower UN troops]] take over the Heinlein Base and "relocate" all [[SemperFi US Marines]] there to a tiny remote outpost]], Major Mark Garroway sends a coded message to his daughter Kaitlin back on Earth, asking her to pass a message to "Uncle Walt". Since he knows [[spoiler:the UN]] is likely to block any message with certain key words, he peppers the message with enough American and Marine-specific references to slip under the radar. The message is "Walt, you sorry-assed son of a bitch, listen up and listen good. The blue boys pulled a Pearl Harbor 1207 GMT 27 May. The boss is down, but okay. Forcibly relocated to Red Planet. Have capped guards and secured cat. Am marching on Derna, with complete openness." "Blue boys" refers to [[spoiler:UN troops, who wear blue uniforms]], "Pearl Harbor" refers to a sneak attack, "the boss is down" means Garroway is in command, "forcibly relocated" means "imprisoned", "Red Planet" is a reference to the Heinlein Base (''Literature/RedPlanet'' is a novel by Creator/RobertAHeinlein), "have capped guards and secured cat" means that Garroway and his people have managed to escape, kill their guards, and obtain transportation. "Marching on Derna" is a reference to a key piece of USMC history - the [[https://en.wikipedia.org/wiki/Battle_of_Derna_(1805) Battle of Derna]] in 1805, which was preceded by a 600-mile march through the desert. This lets the brass know that Garroway and his people plan to make a similar trek across the Martian desert to secure the city of Mars Prime. While it's true that anyone with access to internet would eventually be able to figure out the message, the reason for wording it thus is to avoid automated filters in place by [[spoiler:UN]].
* In ''Literature/ASeriesOfUnfortunateEvents'' VFD members communicate with "Sebald code", in which every eleventh word between two bell rings (or two mentions of bells ringing, if the communication is text-based) is the message. The character of Gustav Sebald, the Volunteer who developed the code, was a famous film director and sent messages with the code in his movies.

** A probably-less-deliberate example happens in the game series (see below).

* ''Series/GetSmart'': In one episode, the Chief (disguised as a singing waiter) communicates a message to Max and 99 by slipping code phrases into the song he is singing.

''[[Literature/TheThrawnTrilogy Heir to the Empire]]'':
* A variation is used: Mara Jade needs to send a message to her boss, Talon Karrde, but there's no way to do so without the message being intercepted by an Imperial Star Destroyer in orbit. Luke Skywalker (who is with her at the time), suggests using a "counterpart encrypt" between his astromech droid (also with them) and his X-wing (in Karrde's possession). The unusual encrypt works; the X-wing's computer decodes the message easily, while everyone else is stumped by it (although the Empire, while unable to ''read'' the message, does at least manage to figure out that the message is ''using'' a counterpart encrypt). While this does leave the Empire suspicious of Karrde, they're not ''that'' suspicious because they know he's a smuggler and his subordinates might have any number of things to say that they'd rather the Empire not know about. The important thing is that it doesn't give them any clue that Karrde was harboring ''Luke Skywalker'', who the Empire desperately wants to capture. Karrde later sends a message back using the same method, via the X-wing.
** Winter tells Han about Ackbar's 'kids' acting up, and he inquires about the 'neighbors' -- the New Republic [[HangingSeperately politicians]] and the Empire, respectively. Problem is, this wasn't a code that they'd worked out beforehand -- actually, they never worked it out at all. Winter came up with it on the fly because she knew they'd be listened in on, and just hoped Han would be able to work out enough of it to be useful. Han knows Winter means there's been some problems, but not just what they mean. This incident was, bizarrely, a case of RealLifeWritesThePlot. Long before the book was released Creator/TimothyZahn told some trusted friends about it and met them at a convention to discuss it further, only to realize that they were surrounded by scifi geeks who would know what he meant if he started talking about Luke and Leia and Han and Chewie, and then he'd be in trouble. So on the fly he called them Brother, Sister, Friend, and Copilot... and it worked.
* In Creator/RobertAntonWilson's ''Literature/{{Illuminatus}}'', a secret society places personal ads reading "In thanks to St. Jude for favors answered -- A.W." as a code to their other members.

* {{Hobo}}s left marks called [[http://www.worldpath.net/~minstrel/hobosign.htm "Hobo Signs"]] on people's fences telling other hobos about the nature of those living there.

* ''The Quest for Saint Aquin'' by Creator/AnthonyBoucher is set in a future where Christianity is banned. The protagonist is a priest traveling incognito, who makes contacts with fellow Christians via coded signs. For instance while stopped at a checkpoint he makes the sign of the cross while apparently searching for his papers. The guard in turn draws the symbol of a fish in the dirt, then scuffs it out and lets him through. Other tricks include having a rosary HiddenInPlainSight as the buttons on the priest's coat.

* ''The Quest for Saint Aquin'' by Creator/AnthonyBoucher is set in a future where Christianity is banned. The protagonist is a priest traveling incognito, who makes contacts with fellow Christians via coded signs. For instance while stopped at a checkpoint he makes the sign of the cross while apparently searching for his papers. The guard in turn draws the symbol of a fish in the dirt, then scruffs it out and lets him through. Other tricks include having a rosary HiddenInPlainSight as the buttons on the priest's coat.

* ''The Quest for Saint Aquin'' by Creator/AnthonyBoucher is set in a future where Christianity is banned. The protagonist is a priest traveling incognito, who makes contacts with fellow Christians via coded signs. For instance while stopped at a checkpoint he makes the sign of the cross while apparently searching for his papers. The guard in turn draws the symbol of a fish in the dirt, then scruffs it out and lets him through. Other tricks include having a rosary HiddenInPlainSight as the buttons on priest's coat.

Alice needs to send a message to Bob without Eve overhearing. Unfortunately for Alice, she can't simply meet with Bob in private to discuss it, and sending a private message is either physically impossible or would arouse too many suspicions. The solution? Send a message to everyone, but encode, encrypt, or word it in a way that only Bob will understand the message. Alice might disguise the message in such a way that Eve will think it's a relatively innocent item, such as an advertisement ({{Wiki/Wikipedia}} lists this technique as "[[http://en.wikipedia.org/wiki/Steganography Steganography]]"), worded so that everyone but Bob will misinterpret the meaning, or simply make the message so hard to decode that only Bob could do it.

They had that code already. "We have a woman's watch here that needs repairing. But I can't find a mainspring. Do you know who might have one?" was one way of saying that there was a woman in need of a hiding place, but none available. Any references to issues with a watch's face meant a Jew whose features were especially Semitic -- "Do you know someone willing to take on the extra risk?" And "This watch cannot be repaired -- do you have a receipt?" meant "Someone has died. We need a burial permit."

* ''Manga/MyHeroAcademia'': [[spoiler: The secret investigation involving TheMole, Hawks, who has infiltrated the [[LegionOfDoom League of Villains]] and discovered they have massively swelled their numbers by taking over the Meta Liberation Army and now have the strength necessary to take on ''all the heroes'' and destroy Japan. The Ppublic Safety Commission can't let anyone know about any of this for fear of moles in their own ranks.]]

* This occurs twice shortly apart regarding the same event in ''Manga/MyHeroAcademia'', specifically [[spoiler: the secret investigation involving TheMole, Hawks, who has infiltrated the [[LegionOfDoom League of Villains]] and discovered they have massively swelled their numbers by taking over the Meta Liberation Army and now have the strength necessary to take on ''all the heroes'' and destroy Japan]]. The public safety commission can't let anyone know about any of this for fear of moles in their own ranks, but the fact something big is going down behind the scenes does unofficially find its way out.
** The safety commission demands that U.A. High restart their student hero internships ahead of schedule, and the U.A. staff quickly (and correctly) deduce the commission has secretly discovered that a major crisis involving the League of Villains looms close and they need every possible hand on deck to combat it.
** [[spoiler:Hawks]] can't directly tell anyone else what he's doing and what's going to go down for fear of being compromised, but is able to give the [[spoiler: #1 Hero, Endeavour,]] the manuscript for the Meta Liberation Army, and tells him to take a look at it sometime, particularly the sections he personally highlighted. [[spoiler: Endeavour [[OutOfCharacterAlert notices something is off about Hawks from his changed demeanour]]]] and reading through the highlighted sections, discovers that the second word of each highlighted section put together assembles a covert message warning him that the endgame approaches.

* In ''Literature/AnneOfGreenGabes'', Anne and Diana signal to each other at night, using their bedroom candles and cardboard to send a certain number of flashes. When Diana sends a "come at once" signal, Marilla is not impressed by this use of candles, fearing a fire.

* ''Manga/FullmetalAlchemist'': Riza Hawkeye uses this to deliver a message to Roy Mustang while she's under surveillance. She gets into a mundane conversation with him over lunch in which she talks about the activities of various people she knows. Mustang is later able to take the first initial of each name Hawkeye mentioned and spell out her message.

* ''Series/ICarly'': In "iPsycho", Carly and the gang need to get a help message out so someone will rescue them from Nora. She's watching their every move, so they ask if they can send a birthday video to their friend Gibby. With Nora watching, they make him a video which contains a secret message.

** "Every fourth!" "Word!" "Every fourth!" "Word!"

* In "The Wedding Job" episode of ''Series/{{Leverage}}'', the sermon Nate delivers at the wedding (while [[BadHabits posing as a priest]]), is clearly intended to be a message to Sofie, who is in the crowd, about their relationship.

* The Special Operations Executive (SOE), which sent many agents into occupied countries during UsefulNotes/WorldWarII, provided them with duress codes and other security checks that would blend in with the normal text[[note]]such as using non-obvious codewords and including/not including certain punctuation characters in certain points of a message[[/note]]. However, when the Gestapo forced captured "pianists" (wireless operators) to send false messages or attempted to use captured equipment themselves SOE headquarters would infamously ignore their own security protocol and keep trusting the communications[[note]]one problem being that radio operators (hastily trained and transmitting under difficult circumstances) would often make mistakes anyway, making it harder to spot actual duress codes[[/note]]. On one occasion, the [[WhatAnIdiot British contact in England told the agent attempting to sound the alarm that they made a mistake]]: "That's the duress code, you need to remember not to use that." Needless to say, things went downhill from there, with many agents being delivered directly into the hands of the Gestapo after the SOE had arranged drops with a captured agent or an enemy operator on the other end.