Interview with MS today: now updated after

[Yax]

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

 

[Reel]

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

His keys only opens his locks. My keys only open my locks.

 

[crystal]

Originally posted by: ReelC00L

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

His keys only opens his locks. My keys only open my locks.

Lets him send an empty open box to you (Who would want to stole an empty box even if it is open, right? ). You put the diamonds in there and send them back. One round way trip. hehehe.

 

[Yax]

Originally posted by: ReelC00L

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

His keys only opens his locks. My keys only open my locks.

I never mentioned that he should lock the box before sending it.

 

[Alternex]

Originally posted by: crystal

Originally posted by: ReelC00L

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

His keys only opens his locks. My keys only open my locks.

Lets him send an empty open box to you (Who would want to stole an empty box even if it is open, right? ). You put the diamonds in there and send them back. One round way trip. hehehe.

Ok do that.. While the box is on it's way I'll intersept it and substitute it with my box then send it to you. Then when you send out the diamonds I'll intersept the package (again) and have the diamonds. A lot of security algorithms fail to spoofing such as this.

Was it ever mentioned that you can lock a box without the key in the first place?

 

[LongCoolMother]

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: cheapbidder01

Originally posted by: ReelC00L

Originally posted by: ReelC00L
#1: You have 8 balls, 1 is lighter than the others but not visually obvious which. You have a balance scale and are only allowed to weigh them twice. How do you figure which is the lighter one?

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

#3: Define the objects (as in OO Programming) that you would need to create the game pac-man.

#1: my answer has been said here. 3 vs 3, go on from there. I figured this one out pretty quickly.

#2: my first answer was not the best answer but it impressed the interviewer because nobody had ever given that answer before. I had suggested something similar as said above where the receiver sends me a lock locked to the outside of the box but not locking the key in. It wasn't the best answer because security was compromised by sharing the key. Then, I rethought it and gave a better answer. Then he pointed out that it would be wasteful on "bandwidth" to send the diamonds 3 times. The best answer that I came up with was only sending the diamonds once and not sharing a key. I can't remember the details of the solution right now. I'd have to think about it but that should be enough to get some of the guys in the forum thinking of the answer.

#3: We really didn't spend a lot of time on this. I just suggested a few objects: Pac-man, ghost, dot, cells. Those were my framework for the pac-man game. He said we could have spent half an hour on this problem on its own but since time was limited, we would stop there.

Number 2 should be the easiest one. Have him send you an empty box. Put the diamond in it, lock it and ship it back to him. He can open the box with his key.

His keys only opens his locks. My keys only open my locks.

I never mentioned that he should lock the box before sending it.

you dont understand. when he sends the diamonds back, he has to lock it. and if he locks it, the reciever ahs no way of opening and getting to the diamonds.

 

[NogginBoink]

Originally posted by: Alternex

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

This is not possible. Mallory can freely swap boxes in transit.. plus he can just steal the boxes without the keys while in transit so no one can get the diamonds! You need a trusted arbitrator (Trent) to help with key exchange. And then nothing can prevent the loss of the boxes in transit.. in computer cryptography land you just send the data again until the receipient receives it.. in this case you don't have that luxury. Get an armored truck and deliver it yourself

I see someone's been reading his Schneier.

 

[Alternex]

Originally posted by: NogginBoink

Originally posted by: Alternex

#2: You have a lock box and need to ship me some diamonds. Anything shipped in the box must be locked or it will be stolen. You have n locks + keys and I have n locks + keys. Any of your keys works on any of your locks and any of my keys work on any of my locks but not each other's. You can ship the box back as many times as you need. How do you get the diamonds to me?
Bonus: relate it to something in computers.

This is not possible. Mallory can freely swap boxes in transit.. plus he can just steal the boxes without the keys while in transit so no one can get the diamonds! You need a trusted arbitrator (Trent) to help with key exchange. And then nothing can prevent the loss of the boxes in transit.. in computer cryptography land you just send the data again until the receipient receives it.. in this case you don't have that luxury. Get an armored truck and deliver it yourself

I see someone's been reading his Schneier.

Makes good nighttime reading.. seriously
Did Mallory and Trent give it away? I told my wife I wanted to name our first born son Trent - everybody trusts Trent after all!

 

[khlee]

I know what i believe to be the best answer but its long and im too lazy to post it on this board

so ha