The movie features a device called a “cryptex” which holds a secret message. It appears to be a combination lock with five dials (26 letters each), not unlike a bike lock. I believe the message is stored in a hollow compartment within the pin. The message is written on a piece of very thin papyrus paper wrapped around a glass tube containing vinegar. There is some sort of hair trigger inside the mechanism that will shatter the glass, releasing the vinegar which supposedly dissolves the message.
It looks like it’s made of brass with marble insets.
And here is a behind the scenes video describing the prop, including the movie clip showing the interior of the device in action at 4:25. (Protip, you can use ‘,’ and ‘.’ to move frame-by-frame on YouTube.)
In the movie, it was apparently out of the question to bypass the lock. “The only way
to access the information is to spell out the password”.
My question is, how secure is this device?
Does vinegar actually dissolve papyrus paper, and would it dissolve fast enough to prevent us from salvaging the message? I am imagining a high speed camera setup. Break the device, quickly remove the solid debris, then review footage.
Can’t you freeze the contraption, then break it? Frozen vinegar presumably won’t dissolve anything.
What about carefully sawing through the end caps?
Multi-dial combination locks of this style are usually vulnerable to attack. By creating tension between the pin and the gates, then turning the dials, you can feel where the gates are. There is such a thing as false gates but these are detectable too. Is the cryptex device vulnerable to such an attack?
Here is a video explaining how this kind of combination lock works.
In principle, water in the vinegar may expand enough before it freezes to crack the vial.
Vinegar is just dilute acetic acid. An appropriate ink might be rendered invisible by an acid. But not in an unrecoverable manner. Actual unrecoverable destruction of the message seems rather unlikely. Papyrus is still just cellulose, ordinary vinegar won’t attack that, certainly not at any speed.
The vinegar may be concentrated, it isn’t too difficult, so the vial may be more dangerous, but even then, there is no instantaneous reaction. It seems it takes quite some time to degrade cellulose with even concentrated acetic acid.
Filling the vial with some form of incendiary chemical would seem a much better plan. A two part mix with its own oxidiser would make for a much more difficult problem.
Even then, there are lots of ways of defeating the mechanism. Bomb disposal workers got pretty good at bypassing anti-tamper mechanisms. Pot the entire thing in wax or a polymer. See how well the trigger mechanism works then.
X-ray the device. There are miniature CT scanners that could just about read the message without opening it, but could certainly get you a very high resolution 3D model of the entire mechanism. Instant decoding.
Use a fine drill into the vial and drain it by holding the device vertical. If necessary, use a vacuum chamber to evaporate the vinegar.
I assume the real thought would be to dissolve a conveniently cooperative ink so the papyrus is blank or unreadably smudged, but that wouldn’t be thrilling enough for Hollywood.
I read about an experiment to CT-scan hyper-baked papyrus scrolls from Herculaneum (near Pompeii). As a result of heat exposure during the eruption, these are simple scrolls of intact charcoal - but the theory is the ink can be detected by a CT scan and therefore the scroll “unrolled” by computer.
You can often open such locks by probing for the gates with a thin shim. I assume this is a real custom puzzle box (not merely a fake prop) someone constructed, and the goal is to open it without damaging it? If you are willing to cheat, the Gordian solution for such things is to X-ray them.
If you assume x-rays can be used, then looking at that video, it’s trivially easy. You x-ray it, which will reveal that the booby trap is a mechanism involving gears. You simply drill into it and insert a pin that jams the gears. Then cut it open. Or figure out a spot where you can drill into the vial, and drain or neutralize the acid
If you assume for the sake of the argument that no x rays are allowed, or that the booby trap is (somehow…) so clever there is no way to do anything invasive without triggering the mechanism, then it’s harder. One possibility is that you put it in a bath of a buffer solution, then use a very small amount of explosives that cut open the tube at both ends. While the acid will be released it will be neutralized by the buffer solution and (hopefully) won’t have time to wipe the message. I don’t know enough about explosives to be able to say whether it would be realistic to be able to blow both ends off a tube without destroying the papyrus.
I read the book (my IQ is now 10 points lower) but I don’t remember the plot well enough to remember whether there was time pressure. If not, a basic mechanism to try all the combinations that could flip the numbers at 5 per second could try every combination in about four weeks.
Drilling into it counts as damage! I said to X-ray it because then you can read the combination.
I thought this was a real puzzle box, and not a hypothetical Harvey’s Resort bomb? Maybe someone has already acquired a reproduction and videoed themselves picking it…
The device in the movie never showed the anti-tamper mechanism except conceptually, and the demonstrated working device was pretty simple. They claimed to be inspired by da Vinci level tech capabilities.
The usual problem with combination locks like this is that there is always some slop in the mechanism, so applying pressure and feeling how it behaves can allow you to feel for the gates. Adding false gates makes breaking it harder. But if you add the idea of an anti-tamper mechanism, the obvious first trick is to make the false gates trigger the anti-tamper. So you cheerfully go ahead and try to crack the device feeling your way through the gates, only to discover that pulling the ends apart when you think you have the right combination just shatters the vial. One might also built the device such that any release of tension on the ends of the cylinder causes the vial to fracture. Anti shimming could be easily designed into the wheels. It is really only the cheapest and nastiest of combination locks that can be decoded with a simple shim. Someone designing it is going to immediately try to come up with clever ways to crack it, and then redesign to cover them. But experience is a good teacher, and there probably wasn’t a lot of experience when the device was claimed to have been built.
One of the big problems building such a device for real is that you need it not to self destruct unnecessarily when faced with ordinary extremes of environment. So you would have to make it proof against self destruction when subjected to freezing temperatures. Also proof against just being dropped. This gives a cracker some wiggle room.
That seems to be a standard movie trope to indicate success. Gives the scene a nice little dramatic jolt as well.
If there were false combinations and/or false gates the spring wouldn’t help. You need to tension the device yourself to feel the movement of the mechanism if you are cracking it, so the spring doesn’t really help. If you are just running through all the combinations it might speed things up. Much would depend on the tolerances it was made to. Realistically they wouldn’t be all that good.
Dammit Terminus_Est!
When I read the OP, my first thought was “I’m the LockPickingLawyer and what I have for you today is a cryptex with a hidden message inside.” Followed later by “Click on 1. 2 is binding.”
All we have to go by, unless there are more details in the book, are the couple seconds from the movie where they go inside the device. I don’t think the prop itself was built with the trigger, but it is supposed to be feasable with tech available c. 1500AD.
I’m guessing it is a hair trigger not unlike a mouse trap where the trip is held up by the pin instead of being pressed against the base plate. When the pin moves the trip gives, thus setting off the device. I assume there is a mechanism such that a correct combination will hold the trip independently of the pin.
Here’s a diagram of what I’m thinking of, excuse the MSPaint.
There is no history, the device is a MacGuffin dreamed up for The Da Vinci Code. The device in the story was sitting in a vault for hundreds of years.
There was no “self-destruct” trigger. The idea is just that if someone who doesn’t know about the mechanism tries to force it open, it’ll ruin the inside.
I don’t think that’s right. It’s been a long time since I read it, but I’m pretty sure the one in the story is brand new.
Right, I assumed by “self-destruct” Chronos meant the message dissolving. Not an explosive.
I’m going by the movie so it may be different, or I may have misinterpreted something. It was at least decades old because the vault manager said explicitly that it hadn’t been opened in decades.
