Who wants a puzzle?

[paulney]

You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Update: if you want a great explanation of the solution, look for QED's post (2nd page)

 

[JJChicken]

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

 

[maziwanka]

Originally posted by: Barack Obama

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

boom. easy.

 

[JJChicken]

Originally posted by: maziwanka

Originally posted by: Barack Obama

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

boom. easy.

In fact, I think it can be done the other way round:

Mail box. Wait for it to be received. Mail key?

 

[paulney]

Originally posted by: Barack Obama

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

Reading comprehension FTL.
You can't mail the key - before or after. Post office people will make a copy and use it on your box later.

 

[jagec]

Originally posted by: paulney

Originally posted by: Barack Obama

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

Reading comprehension FTL.
You can't mail the key - before or after. Post office people will make a copy and use it on your box later.

If you mail the box first and wait for her to recieve it, it doesn't matter if the PO people copy the key or not...as long as they deliver it, which you claim they will.

I would mail a locked box, and then a grinder. Done.

 

[irishScott]

Mail a sledgehammer. Then mail the box.

 

[jagec]

Originally posted by: irishScott
Mail a sledgehammer. Then mail the box.

Err, sledgehammer might not be such a good idea...she might break the diamonds.

 

[paulney]

Originally posted by: jagec

If you mail the box first and wait for her to recieve it, it doesn't matter if the PO people copy the key or not...as long as they deliver it, which you claim they will.

I would mail a locked box, and then a grinder. Done.

Imagine, this is 1800s. Colonization of Frontier or whatever. PO people know who the padlocked box was delivered to, and then they get the key. Boom, your diamonds are gone.

How can you deliver the diamonds _without_ mailing the key?

 

[JJChicken]

Originally posted by: paulney

Originally posted by: Barack Obama

Originally posted by: paulney
You want to mail diamonds to your gf. Suppose, it's the only way to reach her - you have a long distance relationship/whatever.

If you mail diamonds in an open box, post office people will steal them. You can put a padlock on the box, and the diamonds will be delivered safe and secure. You can't mail the key, because it will be compromised right away (post office people will make a copy, then steal your diamonds).

How can you mail the diamonds to the girl, so that she can actually get them out of the box?

Mail her the key first. Wait till it arrives at her destination. Mail the box then.

That was easy

Reading comprehension FTL.
You can't mail the key - before or after. Post office people will make a copy and use it on your box later.

Mail the box first with a note saying "dear sexy lady, open with key i gave you before i left you". Mailman sends box. Wait for her to reply "dear sexy ATOTer, i received the box". Then send her the key. Since the box is already sent and arrived at your GF's place, mailman has no incentive to steal the key.

 

[paulney]

The concept behind this riddle revolutionized crypto industry at some point in time.

 

[JJChicken]

Originally posted by: paulney

Originally posted by: jagec

If you mail the box first and wait for her to recieve it, it doesn't matter if the PO people copy the key or not...as long as they deliver it, which you claim they will.

I would mail a locked box, and then a grinder. Done.

Imagine, this is 1800s. Colonization of Frontier or whatever. PO people know who the padlocked box was delivered to, and then they get the key. Boom, your diamonds are gone.

How can you deliver the diamonds _without_ mailing the key?

Okay, I'll tack on these additional assumptions to try and find the "real" answer to this puzzle.

 

[BigJ]

I get my GF to send her box + padlock unlocked, insert the diamonds, lock the box, and send it back.

 

[paulney]

Originally posted by: BigJ
I get my GF to send her box + padlock unlocked, insert the diamonds, lock the box, and send it back.

How can you lock her padlock without her key?

 

[Kaolccips]

Mail it some other way.


I wasn't aware that you couldn't lock a padlock without a key...
(sarcasm)

 

[BigJ]

Originally posted by: paulney

Originally posted by: BigJ
I get my GF to send her box + padlock unlocked, insert the diamonds, lock the box, and send it back.

How can you lock her padlock without her key?

Should I spoil it instead of trying to dodge it?

<---Comp Sci Major

Hint: Both people can have keys and padlocks, and you can send more than one padlock at a time.

 

[Kaolccips]

Originally posted by: BigJ

Originally posted by: paulney

Originally posted by: BigJ
I get my GF to send her box + padlock unlocked, insert the diamonds, lock the box, and send it back.

How can you lock her padlock without her key?

Should I spoil it instead of trying to dodge it?

<---Comp Sci Major

Spoil it.

 

[elecrzy]

Have her send the padlock while key in her possession...

 

[Kaolccips]

So I'm guessing BigJ got it? That would work unless there was rules left unstated.

 

[irishScott]

Originally posted by: paulney

Originally posted by: BigJ
I get my GF to send her box + padlock unlocked, insert the diamonds, lock the box, and send it back.

How can you lock her padlock without her key?

Easily. IRL, you just close the padlock, it remains locked.

Problem is this is an analogy.

 

[BigJ]

Originally posted by: Kaolccips
So I'm guessing BigJ got it? That would work unless there was rules left unstated.

No I didn't get it. All it was meant to do was to make people aware that you weren't the only one with a padlock.

Bob and Alice are standard names in cryptography. Bob would be you, your GF would be Alice. Eve is the common name for the postal employees trying to steal your shit. We covered this problem at the beginning of the year in my crypto class for HW.

 

[xcript]

Lock -> send -> she adds her own padlock -> sends back -> remove your lock -> send to her again -> she takes off her lock and enjoys the contents. No key was ever sent.

 

[BigJ]

Originally posted by: xcript
Snip

Shhh! You ruined it!

 

[irishScott]

Originally posted by: xcript
Lock -> send -> she adds her own padlock -> sends back -> remove your lock -> send to her again -> she takes off her lock and enjoys the contents. No key was ever sent.

Sweet. Hilariously impractical IRL, but sweet.

 

[Locut0s]

Originally posted by: irishScott

Originally posted by: xcript
Lock -> send -> she adds her own padlock -> sends back -> remove your lock -> send to her again -> she takes off her lock and enjoys the contents. No key was ever sent.

Sweet. Hilariously impractical IRL, but sweet.

That's the concept behind public key encryption, which is anything but impractical.