Self-Destructing Security

It is a fact that no safe can ever be impregnable. Even a meter thick titanium box could be cut through eventually. Security measures are designed with the intent of making any attempted break in so time consuming and recognizable that the thieves will be apprehended before they can succeed. So long as the thieves were somehow able to secure themselves sufficient time and privacy however, there are ways of penetrating just about any physical security.

But while you can't make it impossible for thieves to get in, you can make it impossible to get anything out intact if they don't use the proper access method. So long as it's more important that the contents stay out of the wrong hands than in one piece, you setup a failsafe that will destroy the contents before an attempted break in can be completed. The technique also has the advantage of not requiring any staff to check on the security regularly, and so is good for security that will be unattended for long periods.

This is typically used to protect information rather than unique objects, as it's easier to have a backup copy so that the loss of any single copy doesn't mean it's lost forever. However it can also be found used with unique items that would be dangerous in the wrong hands, under the logic that it's better for no-one to have it than the wrong people.

Compare Self-Destruct Mechanism, which is typically deliberately triggered by the owner of vehicles, buildings and bases, and This Page Will Self-Destruct where messages self destruct on a timer to avoid falling into the wrong hands, rather than being triggered by an attempted theft.

See also Booby Trap, which the intent is to destroy the thief more than the loot. When this technique is used by a person to kill themselves to avoid torture/giving up secrets, that's Cyanide Pill.

Examples of Self-Destructing Security include:

Anime and Manga

Death Note: Light goes to great lengths to protect the Death Note. Not only is it hidden in his locked bedroom in a secret panel of his desk drawer, but opening the panel without first deactivating the failsafe will incinerate the notebook before it can be found. After all, if someone else takes it he's unlikely to get it back, and it links him to hundreds of murders.

Comic Books

Batman has this on his Batmobile. He has a number of deterrents to prevent crooks from jacking the Batmobile, up to five levels. The fifth level being detonating the Batmobile. Batman nearly became a victim of this in the final part of the Knightfall storyline, KnightsEnd when he attempts to use the Batmobile to hunt down the rouge "Az-Bats" Jean-Paul Valley and it ends up blowing up on him. The incident causes Nightwing to go on a Roaring Rampage of Revenge on Jean-Paul, but Robin later finds out Bats is safe. Turns out he realized that Valley did the same thing he would have - just not that deadly.

Film

The Holy Grail in Indiana Jones and the Last Crusade is protected by many layers of secrets, guards and traps. The final resort, however, is that the Grail can never pass beyond "The Great Seal". Doing so results in the entire place self destructing and the Grail being lost forever.
James Bond
- From Russia with Love: Bond's attache case has numerous built-in gadgets including a magnetically attached tear-gas canister stored inside. Opening the case without first rotating the clasps triggers the grenade and gives any would-be-snoop a face full of the gas. This turns out to be just the edge Bond needs when held at gunpoint by Red Gran, whose greed Bond uses to trick him into opening the case.
- Goldfinger: As a shout out, it's implied that Bond's case still has similar defensive measures in the following film, even though they're never explicitly mentioned. After being captured, he talks to one of Goldfinger's henchwomen on the plane.

Bond: Did any of my luggage survive with me? And my attache case?
Mei-Lei: Black attache case damaged when examined. So sorry.
Bond: Apologies quite unnecessary.

- For Your Eyes Only: Bond's car has an anti-theft measure which blows it up if it's broken into. Considering all the high tech gear in every car Bond drives, it's probably more to protect those things than the car itself.

Literature

In The Da Vinci Code, the cryptex protects its contents with a combination lock. Attempting to force the cryptex open will break the vial of vinegar inside, which would dissolve the papyrus along with its message before it could be read. As a result, only the right password will grant access to the message.
- And yet no one thought to put the canister in a freezer for a few hours and crack open the thing worry-free.
  - That's...that's brilliant.
The Matthew Reilly short story Altitude Rush (Available in pdf on his website) has documents protected by a self destructing case that will release hydrofloric acid on the papers unless properly accessed. The case also has an altitude sensor that will trigger the self destruct if it goes above 1000 feet or below 10 feet, necessitating the thieves to execute a frantic escape across the NY skyline.
In The Dresden Files the stolen Shroud of Turin is kept like this, with a remote to deactivate the security. In this case it's a precaution against the seller being subjected to You Have Outlived Your Usefulness after handing it over.
The Dark Is Rising series novel The Dark is Rising. The Book of Gramarye is kept in a grandfather clock with a magical security mechanism. If the Book touches the clock's pendulum while it's being removed or returned, it is totally destroyed. The same thing will occur if an Old One tries to remove the book and they're not touching a specific human being at the time.
Tom Clancy novel The Cardinal Of The Kremlin. The information from the title spy would be typed up in the American Embassy on flash paper and inserted into a container which would ignite if anyone tried to mess with it. It was then transported by diplomatic pouch to CIA headquarters, where it was disarmed in the office of the CIA Director.
Robert A. Heinlein's The Number of the Beast. Computer software expert Deety mentions that if anyone except herself attempts to access her college computer account it would show them her "clean" financial records while secretly deleting the "dirty" copy.
In Jeffery Kooistra's Dykstra's War, the eponymous Dykstra receives a thumbprint-coded package that, if accessed by the wrong person, will explode with sufficient force to take out the whole building. Clearly one wants to be very careful about checking the address labels.

Live Action TV

In Season 4 of Burn Notice, an important MacGuffin is buried in a graveyard in an airtight container, which also contains highly reactive chemicals that would explode when exposed to the air. Filling the grave with machine oil allows them to get inside safely.
In the New Year's Day 2012 Sherlock episode "A Scandal in Belgravia" Irene Adler's phone, containing lots of politically-sensitive data, contains miniature explosives that will destroy it if anyone attempts to physically remove the hard drive.
The pilot episode for the show White Collar features this in the beginning. Peter and his team are attempting to crack open a safe that has a counterfeiter's information in it. If they can get into the safe, they'll have enough evidence to arrest the counterfeiter. Unfortunately, as soon as they crack the safe, an explosive charge destroys everything inside, showing Peter and his men with confetti.
In Farscape, the ancient Luxan ship is equipped with a self-destructing security mechanism powerful enough to blow up the ship it's parked in. Thankfully, it also loops through a vocal message explaining how to defuse it: It requires any one of three keys only a Luxan is supposed to have.
One episode of It Takes a Thief had hostile foreign agents coerce Al Mundy to deactivate a high-explosive version in a courier's briefcase — after they'd accidentally triggered the mechanism. Al warned them that he didn't do his best work under that kind of pressure. In the end, though, he swapped the red "Armed" and green "Safe" filters over the "Status" light, making the agents think the bomb was now shut down. They walked out with it, not troubling to murder Al or the courier, and were in their car before—

Tabletop RPG

Shadowrun.
- Matrix software
  - The Scramble IC program is often used to protect computer datastores with valuable information. If a decker tries to break through the Scramble and fails, it will overwrite the stored information with random characters, rendering it worthless.
  - A decker tries to disarm a Data Bomb protecting a file and fails. If the Data Bomb was programmed to do so, it will erase the file it was protecting.
Dungeons and Dragons
- Explosive Runes spell (before 4th edition) could be used like this. The caster would cast the spell on the object to be protected. If anyone read the runes, they would explode and destroy the object and whatever it contained (unless immune to magical fire). The caster and those instructed by the caster can avoid triggering it.
  - The classic two-pronged approach is Explosive Runes (or other similar trap) plus Illusionary Script or Secret Page: there are several Anti-Magic effects that can disable or remove such traps, but they would also suppress or destroy the magic text.
- Basic D&D module CM1 Test of the Warlords, Encounter 1 "The Ruins of Alinor". The PCs can find a golden box that radiates magic. If they smash or pry open the box, its contents burn up in a flash. If it is unlocked normally or its lock is picked by a thief, they will find two magical scrolls and a diary.
- Occurs twice in the adventure T1-4 The Temple of Elemental Evil.
  - In one room there's a chest with a chlorine gas trap that functions no matter how the PCs try to disarm it. When they open the chest they find what appears to be spell books and a magical scroll that have been partially dissolved by the gas. In fact they were covered with gibberish and therefore worthless - it was just a trick to make the PCs think they had lost a chance to gain valuable items.
  - Senshock, one of the demon lord Iuz's minions, knows some of his master's secrets. If anyone (such as a group of PCs) uses Charm or any other Mind Control effect to make him reveal these secrets, Senshock will suddenly and mysteriously die, slain by luz himself.
- Module DA1 Adventures in Blackmoor. All of the Iron Duke's agents in the Comeback Inn (as well as the Warden in the Prison Out Of Time) have a special Geas placed on them. If anyone uses torture or magic to try to force them to tell about the plane to kidnap King Uther, the Geas will kill them.
Hot Chicks RPG. Escorts from the Arcturus Escort Corporation have built-in cybernetic data recorders to capture their clients' secrets. If anyone tries to tamper with an escort's recorder it overloads, destroying the stored data and killing the escort.

Video Games

In the videogame Uplink one of the security measures you can purchase for your gateway is a self destruct mechanism as a last resort if the Feds are closing in on you. You lose all the hardwear, but get to keep your reputation and avoid being disavowed (ie, gameover).
In Infocom's Enchanter there's an mechanical egg with a scroll inside. No matter how you open it, the egg shreds the scroll so it's unusable. You later get a spell that allows you to reconstitute the scroll and learn the spell on it.
In System Shock 2, if you trigger an ICE node when hacking open a security crate, it sets off a built-in explosive charge, destroying the crate and its contents (and on any difficulty higher than Easy, probably kills you in the process).

Western Animation

Star Trek: The Animated Series episode "The Slaver Weapon". The title device had an AI computer programmed to make sure its user was a Slaver authorized to operate it. When the Kzinti that found it asked ignorant questions of it, it assumed that it had captured by its master's enemies and tricked them into activating a self-destruct setting which destroyed it...and them.

Real Life

U.S. top-secret documents are carried in briefcases that are booby-trapped with oxidizer bricks, which incinerate the documents if the case is opened without the disarm key inserted.
WW 2 Uboat codebooks were printed on paper that would dissolve in water. Not only did this make the codebook easy to destroy, even if the crew were killed before they could do so, an attack on the sub would be very likely to cause the codebooks' destruction anyway.