uniqueness of car keys

One day as my mother was leaving the house in a hurry, she accidentally picked up the wrong set of car keys. She did not realize this until after she got back home, however, because the keys she had picked up worked fine. She had been driving her 1995 Ford Escort around all day with the key to my grandfather’s 1995 Ford Ranger. This struck me as being particularly odd, considering the differences between the two vehicled involved - if it were two Escorts I wouldn’t be that surprised, but a compact car and a pickup truck?? (By the way, this was definitely not an issue of stripped keys or old ignitions, because the incident happened in 1996.)

The Mailbag item: Are car keys unique? Can you unlock someone else’s car with your key?.

The subject of opening other cars with your key has been covered in depth in this forum before, but I don’t think anyone addressed keyless entry systems?
Have the designers of those been lazy as well? You’d think you could have billions of combinations easily programmed in, but is that in fact the case?
Just wondering, now that I finally have a vehicle with keyless entry. :slight_smile:

If keyless entry systems are properly designed, with good random-number generators, zero knowledge protocols, and secure encryption, they’re completely secure (at least, until the crook breaks in a window, or cuts out the lock mechanism, or whatever). That said, I have no clue whether they’re properly designed.

FWIW, I used to work for a company with a fleet of Ford Escorts. One day, we discovered that the key to a certain one would open and start every Escort in the fleet. Nice.

In my office I found out that I can get copies made of all the Yale brand keys we have in the office. My office manager finally told me I can just go get copies made and I don’t have to wait for her slow ass to get them. Thanks! Perhaps I’m thinking of hotels where the key blanks are proprietary, and not trivially obtainable, and security is often as thick as a glass window. The possiblilities for abuse are awful great. Its kind of like how I walk right out past the Guard with a loaner laptop, but when I bring out the broken monitor he wants to see my property pass. But wait! if I unload 40 macintoshes out the back loading dock the property pass is not needed, just ask the elevator man. It sure must be hard to setup effective security.

Now that is one classy company!

On the early '80’s to early '90’s Fords, Lincolns, and Mercurys with keyless entry, the process was controlled by a smallish black box which mounts on the underside of the package tray in the back window. Each one has a sticker with the code for that box right on it, and in years of dismantling cars I’ve sorta noticed (and yesterday I picked through the ones I still have) that the 5 digit code seems pretty random. None of the ones I still have match or seem to share any other simularity besides having 5 numbers.

SDSTAFF Dogster

Emerald Rogue! Wronger of Rights! Pincher of Sensitive Areas! - Zorak

Suddenly, the scenes in Ghost Dog seem much more credible.
How long could it take a generator to go through 100,000 combinations?
Ok. A little over a day at one combination per second, but if the system allows, say, one per microsecond, I could unlock any of these pathetic 5 digit keyless entries in a minute or two.

Is it really that complicated to use PGP and/or rotating cyphers with a 1024 bit ranges?

There was a 20/20 or dateline or one of those that did a segment on this topic. It seems the keyless thing is just like a garage opener that sends a code chosen among a large number.

Crooks have a receiver that catches the code and can reproduce it.

They did this multiple times at a big parking lot. Someone comes in and parks and locks / unlocks the car using the remote. The TV crew use the gizmo to catch the code and then walk up to the person and proceed to demonstrate they can open their car. All car owners were very surprised.

Two items:

  1. SDSTAFF Jill says:

I’ve got the sneaking suspicion that Bob probably said 1,048,576 rather than 1,480,576. The reason is that the former is 2^20 (2 to the 20th power), which would be the number of ways to make a key that either had, or didn’t have, any or all of 20 properties, whereas the latter is 269 x 43 x 2^7, with 43 and 269 being primes. For this to be correct, there would have to be something about the key that could be done in exactly 43 ways, and something else that could be done in exactly 269 ways. It’s possible, I suppose, but speaking as a combinatorist, I’m betting that it’s a hell of a longshot.

  1. Jill also says:

Just three days ago, I lost one of the keys to my 2000 Honda Accord. My wife had had a duplicate made at the local hardware store (we were unaware that it had one of these chips in it), and it got us into the car just fine. It would even enable us to turn the key to the setting that enables one to turn on the radio, and so forth. But it wouldn’t let us start the engine. (Fortunately, there had been two original keys, and we still had the other.)

So (for late-model Hondas, anyway) the key from the local Ace Hardware will keep you from getting locked out of your car - and the local locksmith can also get you in. (Found this out from experience, too.) But if the key that you got from the dealer isn’t in there, you’re SOL.

Jill adds:

Thank goodness, replacement keys to the Accord are only $90 each. But I’m getting a couple of them, just in case.

[[I’ve got the sneaking suspicion that Bob probably said 1,048,576 rather than 1,480,576.]] No, he said the latter, but … jeez, RT! I gotta watch those details.
(Or you need to go outside more… one or the other :))

I have a newish car that has one of those transponders in the keys, and Toyota quoted me some really high price to get copies made (although not anything like $2900), but I found that a local locksmith could make copies for $35. They had some sort of cheat-sheet for lots of different models of cars, and could actually program the code for the key by engaging in an elaborate sequence of actions that apparently differed for each of the cars. I wasn’t watching that carefully, but in my case they had to start and stop the car , remove the old key, put the new one in, turn the key on, push the gas pedal in a few times, hit the brake, push the gas pedal, <some more steps that I’ve forgotten>, and wait a couple of minutes while some light on the dash was blinking. The first 3 or 4 times they tried it didn’t work somehow, but eventually they got the sequence down, and I had them make 3 keys for me (my wife loses things all the time). So apparently not all of the car companies are trying to create a monopoly on making duplicate keys. I recommend that Lexus owners try calling higher-end locksmiths in the area to see if they can duplicate keys before shelling out thousands of dollars at the dealership.

Hardlyb is correct.
A dupicate key can be made and programed into a car if a locksmith has the proper tools. The programming for additional keys differs from car to car. (my shop manual on this is… in the shop) Some are simple (fords) Others are a royal pain in the ass (Mazda)
Now Loosing the egsiting keys is a whole different ball game.
Chrysler and Mazda require the Locksmith to make a key then program the key in thru an elaborate system designated by a code the factory has on file with the VIN number. Fords and GMs can be programed thru the Diagnostic computer.
Toyotas CANNOT be reprogramed if ALL existing keys are missing. They require the replacement of the ECM chip at around 2900 dollar.
Many locksmiths have gotten out of the automotive industry because the expense of the equipment is to great to realize a profit.
As more and more newer cars come out more locksmiths will jump on the automotive bandwagon.
Till, then. Make lots of phone calls to get the best deal.

Osip

I agree with all of what’s been said about new cars, Hondas particularly. My sister recently bought a 2000 Honda Civic in Minneapolis, which someone promptly tried to steal from her (and I thought Eagan was a nice place!). Apparently they had a Honda Civic key to insert into the ignition to start the car, but unfortunately not the right one. My father told me (so this is a little hearsayish–I don’t have direct evidence) that the incorrect key shorted out the car’s electrical system.

Hoohah! Major billage. But they didn’t get the car, FWIW.

DO NOT BELIEVE THE LOCKSMITHS quoted on this one.

They have done the math on the Possible number of combinations, which is just wrong.

No car company (nor any other key manufacturer) uses random combinations.

They all use the Master/ Slave concept. This changes the numbering considerably. For many models, the door contains fewer cylinders than the ignition for the same key. It’s just cheaper that way.

They also simply don’t care if combinations are repeated, so they do it. Less instructions for the key cutting machine.

If you’ve ever had to copy keys (I did when I once worked in a harware store) you’ll notice that the “extreme” combinations never appear, i.e. Level 1 trough followed by Level 5, followed by Level 1 again. That would make the key very sharp and also very fragile, since the 5 spike would have little side support.

In addition, on models as late as the 50’s, they had master keys to issue to police and locksmiths to enter a car without the classic coathanger.

Actually those are try out keys. It is to damn big of a headache to master a car lock. Try-out keys rely on half cuts and the tolerance in the lock. An example would be the newer 10 cut ford system. The 10 cut system has 10 cuts on the key, 1-6 in the door and 4-10 in the ignition. The number of keys in a typical try-out set for these models are just over 100 keys.
Osip