Some lady brings in a bike lock and...

[MAME]

assumes the lockshop can magically break the code. There's 4 numbers from 0-9 each so that's 10,000 possibilites.

We tried factory defualts but that rarely works. So she expected us to figure it out for her (HAHA, YEAH RIGHT) but instead of wasting hours randomly picking combinations, we just threw it on the table.

But now I'm curious, is there any algorithm that isn't the brute force method of finding the combination (making no illogical assumtions)?

Brute force works ok, O(n), but for 10,000 combinations, that's not very great. I doubt it's possible but I thought I'd ask the community first.


NOTE: she's a fellow state employee, there aren't any charges. She wanted it done from the kindness of our big hearts.

 

[Kelvrick]

How much would a replacement cost?

Tell her you opened her lock, and even polished and removed all teh scratches, then charge her how much the new one cost.

 

[IcemanJer]

without knowning any information, brute force is your only option.

 

[z0mb13]

brute force: cut it off!!

 

[Electric Amish]

I've actually done this before.

It just takes a little patience. Charge her by the hour.

 

[Jzero]

The biggest problem with a combo lock is the time it takes to spin the dials. You could try 10k combinations in a second on a computer, but when turning all the dials by hand takes forever. It took me an hour to brute force a 3-position lock once.

 

[MAME]

Originally posted by: Kelvrick
How much would a replacement cost?

Tell her you opened her lock, and even polished and removed all teh scratches, then charge her how much the new one cost.

You could get a brand new one for $15 at the local bike shop. She's a fellow state employee, we don't charge money or anything.

Otherwise you're right, it's not worth it.

 

[MAME]

Originally posted by: Jzero
The biggest problem with a combo lock is the time it takes to spin the dials. You could try 10k combinations in a second on a computer, but when turning all the dials by hand takes forever. It took me an hour to brute force a 3-position lock once.

nm, read it wrong.


turning the dials isn't hard if you only increment one of them by one 9 times out of ten

 

[MAME]

Originally posted by: z0mb13
brute force: cut it off!!

hahha, nice

 

[aircooled]

We have same laptop locks at work and when you hit the right number, you can just "feel" it settle in or something. hard to explain, but you can tell when you've hit the right number.

 

[DrPizza]

Do you have a pic of the type of lock? I used to have a blast when I was a kid by picking the locks, taking them apart, changing the combination, and putting them back together.

It was hilarious (to me) when someone couldn't unlock their own lock. You'd see them kinda scratch their head and try again.

 

[DrPizza]

btw, on most locks that I've run across that have so many possible combinations (permutations is a better word for it though), I've found that there's a little leeway on each number... That is, on a safe, if the combo is 10-20-30, it can be anything from 8 to 12, 18 to 22, 28 to 32. Thus, using brute force, you could start with 0 0 0, then 0 0 3 then 0 0 6 then 0 0 9 then 0 0 12, 0 0 15, ...

 

[Description]

tw, on most locks that I've run across that have so many possible combinations (permutations is a better word for it though),

It's a combination, not a permutation.

We have same laptop locks at work and when you hit the right number, you can just "feel" it settle in or something. hard to explain, but you can tell when you've hit the right number.

I've found that there's a little leeway on each number.

Those are extremely poor quality toys. I suppose it's worth a try.

 

[MAME]

http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments


NOTE: this is just a picture of the style of lock, not the actual model.

 

[Electric Amish]

# Flexible steel cables for strong cut resistance
# Combination locking mechanisms for keyless convenience
# Protective coating helps prevent scratching
# Ideal for bicycles, skateboards, and sports equipment

How do you lock up a skateboard???

 

[Kelvrick]

Originally posted by: MAME
http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments

What do you usually use to pick?

 

[Ogg]

Originally posted by: Electric Amish
I've actually done this before.

It just takes a little patience. Charge her by the hour.

I did too and got lucky. Opened after only about 20 minutes of trying number combos

 

[MikeyIs4Dcats]

Originally posted by: MAME
http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments

FOUR dollars and 99 fvcking CENTS!?!

 

[DrPizza]

Originally posted by: Description

tw, on most locks that I've run across that have so many possible combinations (permutations is a better word for it though),

It's a combination, not a permutation.

We have same laptop locks at work and when you hit the right number, you can just "feel" it settle in or something. hard to explain, but you can tell when you've hit the right number.

I've found that there's a little leeway on each number.

Those are extremely poor quality toys. I suppose it's worth a try.

it's a permutation. Suppose you make a lock out of 10 digits, 0 through 9. And, you can only use each digit once. There are 10*9*8 different locks you can make. 123 is different from 213. Thus, it's a permutation. A combination lock is a permutation.

Using 3 different digits out of 10, there are 720 permutations, but only 120 combinations.

 

[ElFenix]

Originally posted by: Electric Amish

# Flexible steel cables for strong cut resistance
# Combination locking mechanisms for keyless convenience
# Protective coating helps prevent scratching
# Ideal for bicycles, skateboards, and sports equipment

How do you lock up a skateboard???

with a lock, duh

 

[Eli]

With those turney dial type of locks, I can usually get a feel for when the number is in the right position, and get them undone within a few tries.

Maybe not the more professional masterlock ones, but the cheapo bike ones, definately.

 

[MAME]

Originally posted by: Kelvrick

Originally posted by: MAME
http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments

What do you usually use to pick?

we RARELY do bike locks. Quikset, Corbin Russwin, Best and random cabinet locks are the only thing we'd pick (but RARELY CR and Best since we have the master keys).

 

[DrPizza]

Originally posted by: MikeyIs4Dcats

Originally posted by: MAME
http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments

FOUR dollars and 99 fvcking CENTS!?!

You've gotta be kidding me!!! Those are the crappiest locks, period! Just put a little tension on the lock and start from left to right. When it's on the right number, you'll see the gap between the numbers move over ever so slightly.

 

[Eli]

Originally posted by: DrPizza

Originally posted by: MikeyIs4Dcats

Originally posted by: MAME
http://www.masterlock.com/cgi-bin/product_detail.pl?sub_cat_id=D8143&template=style


combination cable lock. can't pick it, no cylinder. Otherwise it'd be open in moments

FOUR dollars and 99 fvcking CENTS!?!

You've gotta be kidding me!!! Those are the crappiest locks, period! Just put a little tension on the lock and start from left to right. When it's on the right number, you'll see the gap between the numbers move over ever so slightly.

Yup.. that works too.

When you pull on it, you can feel tension on the keys as you turn them. You'll feel when the slot is in the right spot, because the tension will change or shift or whatever.

 

[DrPizza]

Heck, whenever I see a kid with a bike lock like that, I show them how easy it is to open it, as a public service. I hate to see kids bikes get stolen. With a little practice, you can open those things without a combination just as fast as someone who HAS the combination.

edit: and those are the easiest ones to change the combinations on too! Unlock, remove a snap ring, rearrange the order (you can't change the numbers), replace snap ring... done!


LMAO, just remembering the rude kid at the pizza shop 2 years ago. Frequent customer, I warned him that he should quit being rude. He didn't learn. I changed his combination, got a coworker to help, and locked his bike up out of his reach.