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Your iPhone just got less secure. Blame the FBI

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Re: Your iPhone just got less secure. Blame the FBI

#181

Post by titzer »

the_ancient wrote: post #163
studentrob wrote: post #97

Earlier quoted context omitted.

Here's the oath stated by FBI agents when they join [1], > I [name] do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the…

That oath is worth nothing given the Greatest threat to the Constitution is the FBI, NSA and other parts of the Federal Government They may swear a oath to the constitution, but they are actually Loyal to the Federal Government, not the Constitution.

Your comment is snarky but on the money. I have a very, very bad feeling we're losing our Republic to the State and its various apparatuses.

Re: Your iPhone just got less secure. Blame the FBI

#182

Post by pklausler »

ricardobeat wrote: post #178
wrsh07 wrote: post #170

Earlier quoted context omitted.

I find it clearer if you have 100 doors. Pick one. The host eliminates 98 doors [with no prize behind them]. Do you switch? Or do you stick with your original guess? As the parent mentioned, switching gives you a 99/100 chance of being correct, staying gives you a mere 1/100 chance.

I don't see why the other door has 99x more probability of being correct. It's still 50/50, original door or remaining door, the other 98 don't change the odds.

Your initial pick has a 1/100 chance of being right. If you switch, and you were right, you lose. On the other hand, your initial pick has a 99/100 chance of being wrong, and if you were wrong, and you switch, you win. So switch.

Re: Your iPhone just got less secure. Blame the FBI

#183

Post by gravypod »

kazinator wrote: post #91

This is awful reporting. For weeks, the experts in security had been saying that FBI does not in fact need Apple's help to get into that phone; that they are just posturing in order to obtain a back door. This was posted on the ACLU website: https://www.aclu.org/blog/free-future/one-fbis-major-claims-... The FBI can simply remove this chip from the circuit board (“desolder” it), connect it to a device capable of read…

I don't know about anyone else, but the iPhones seem to be the focus of all the academics that do security research.

I'm always seeing X done to the iPhone.

Just these past few weeks I remember seeing a key extraction done via EM emitted from the phone.

Re: Your iPhone just got less secure. Blame the FBI

#184

Post by woodman »

jfoster wrote: post #164
woodman wrote: post #127

Earlier quoted context omitted.

So have you not heard that this would set a legal precedent? Apple would get pestered until they finally create an automatic gateway for turn key security breaking, not unlike the wiretap portals setup by telecoms - or the frequently abused youtube DMCA mechanisms.

It wouldn't set a legal precedent unless a court ruled on it. It would only have come to that if Apple continued to decline the FBI's request.

Again, victim blaming. How is that any different from the false choice "We can do this the hard way, or the easy way"?

Have you considered what will happen to the number of such requests as devices continue to become more secure?

Re: Your iPhone just got less secure. Blame the FBI

#186

Post by pklausler »

pklausler wrote: post #180
adekok wrote: post #88

Earlier quoted context omitted.

> The probabilities change, even when a door you didn't pick [and doesn't hold the prize] is opened. That's the common misunderstanding of the problem. Most people think that the probabilities go fro 1/3, 1/3, 1/3 to 1/2, 1/2, after choosing a door and having Monty Hall open one of the others. The probabilities don't change. The probabilities are 1/3, 1/3, 1/3 at the start. After you choose a door, they're still 1/3,…

This is good reasoning. Unlike other probability puzzles, the new information isn't useful in this one. P(my first choice was right) = P(my first choice was right | given that I've been shown a goat in another door) It's my second-favorite probability puzzle; my favorite is the one in which the new information has no relevance at all but still changes the probabilities, the "not both daughters" problem.

I should have just given the other problem, sorry for the laziness.

Your friend tells you that she has two children. They're not both boys, she adds. What are the odds that they're both girls? (Obviously 1/3).

When she tells you that one child is named Mary, the odds that they're both girls change (to 1/2)! Even though you knew that at least one of the children was a girl, and the name might as well be arbitrary, and the new information seems useless... the odds have changed.

It's nontrivial to work this one out; exercise for the reader.

Re: Your iPhone just got less secure. Blame the FBI

#187

Post by jinfiesto »

zodPod wrote: post #165
adekok wrote: post #88

Earlier quoted context omitted.

> The probabilities change, even when a door you didn't pick [and doesn't hold the prize] is opened. That's the common misunderstanding of the problem. Most people think that the probabilities go fro 1/3, 1/3, 1/3 to 1/2, 1/2, after choosing a door and having Monty Hall open one of the others. The probabilities don't change. The probabilities are 1/3, 1/3, 1/3 at the start. After you choose a door, they're still 1/3,…

This is a great clarification of how this problem works. I STILL can't grasp why you'd switch. Since you have no idea which door it is, couldn't the 2/3 probability be applied to either his door or your door? For all you know, the one that he removed was just one random one of the goat doors. Your chance of picking the car was 1/3 before, if you could have the car already, why would it be better to switch now that he…

From the initial setup you have a 1/3 chance of choosing the correct door and a 2/3 chance of choosing the wrong door.

The key to this problem is the behavior of the game host as he will never reveal the door with the car. So, after he reveals the contents of one of the doors, if you choose not to switch, you still only have a 1/3 chance of having chosen the door with the car.

On the other hand, if you choose to switch, 2/3 of the time you will have chosen incorrectly initially, and under the switching strategy, those 2/3ds of the time you are guaranteed to win the car. Hence, you have a 2/3ds chance of winning under the switching strategy, vs a 1/3d chance of winning under the "staying" strategy.

Hope this clarifies things.

Re: Your iPhone just got less secure. Blame the FBI

#188

Post by logfromblammo »

zodPod wrote: post #165
adekok wrote: post #88

Earlier quoted context omitted.

> The probabilities change, even when a door you didn't pick [and doesn't hold the prize] is opened. That's the common misunderstanding of the problem. Most people think that the probabilities go fro 1/3, 1/3, 1/3 to 1/2, 1/2, after choosing a door and having Monty Hall open one of the others. The probabilities don't change. The probabilities are 1/3, 1/3, 1/3 at the start. After you choose a door, they're still 1/3,…

This is a great clarification of how this problem works. I STILL can't grasp why you'd switch. Since you have no idea which door it is, couldn't the 2/3 probability be applied to either his door or your door? For all you know, the one that he removed was just one random one of the goat doors. Your chance of picking the car was 1/3 before, if you could have the car already, why would it be better to switch now that he…

The important bit is that Monty will never choose to show you the winning door, and he will always show you a door after you pick a door and before asking you if you want to switch. He always opens a losing door.

The location of the prize and the player choice of door are independent events. Monty's choice is dependent on whether the player choice and the prize location are the same. Monty will never open the door the player picked. Monty will never reveal the prize. Those rules generate exploitable information for the player.

Here is the complete probability tree, and two possible strategies of play:

  Prize behind door A;  P = 1/3                           ALWAYS STAY strategy:
    Player picks door A;  P = 1/3 * 1/3 = 1/9               P(WIN) = 1/18 + 1/18 + 1/18 + 1/18 + 1/18 + 1/18
      Monty shows Door B;  P = 1/3 * 1/3 * 1/2 = 1/18              = 6/18
        Player stays with A;  WIN                                  = 1/3
        Player switches to C;  LOSS                         P(LOSS) = 1/9 + 1/9 + 1/9 + 1/9 + 1/9 + 1/9
      Monty shows Door C;  P = 1/3 * 1/3 * 1/2 = 1/18               = 6/9
        Player stays with A;  WIN                                   = 2/3
        Player switches to B;  LOSS
    Player picks door B;  P = 1/3 * 1/3 = 1/9             ALWAYS SWITCH strategy:
      Monty shows Door C;  P = 1/3 * 1/3 * 1/1 = 1/9        P(WIN) = 1/9 + 1/9 + 1/9 + 1/9 + 1/9 + 1/9
        Player stays with B;  LOSS                                 = 6/9
        Player switches to A;  WIN                                 = 2/3
    Player picks door C;  P = 1/3 * 1/3 = 1/9               P(LOSS) = 1/18 + 1/18 + 1/18 + 1/18 + 1/18 + 1/18
      Monty shows Door B;  P = 1/3 * 1/3 * 1/1 = 1/9                = 6/18
        Player stays with C;  LOSS                                  = 1/3
        Player switches to A;  WIN
  Prize behind door B;  P = 1/3
    Player picks door A;  P = 1/3 * 1/3 = 1/9
      Monty shows Door C;  P = 1/3 * 1/3 * 1/1 = 1/9
        Player stays with A;  LOSS
        Player switches to B;  WIN
    Player picks door B;  P = 1/3 * 1/3 = 1/9
      Monty shows Door A;  P = 1/3 * 1/3 * 1/2 = 1/18
        Player stays with B;  WIN
        Player switches to C;  LOSS
      Monty shows Door C;  P = 1/3 * 1/3 * 1/2 = 1/18
        Player stays with B;  WIN
        Player switches to A;  LOSS
    Player picks door C;  P = 1/3 * 1/3 = 1/9
      Monty shows Door A;  P = 1/3 * 1/3 * 1/1 = 1/9
        Player stays with C;  LOSS
        Player switches to B;  WIN
  Prize behind door C;  P = 1/3
    Player picks door A;  P = 1/3 * 1/3 = 1/9
      Monty shows Door B;  P = 1/3 * 1/3 * 1/1 = 1/9
        Player stays with A;  LOSS
        Player switches to C;  WIN
    Player picks door B;  P = 1/3 * 1/3 = 1/9
      Monty shows Door A;  P = 1/3 * 1/3 * 1/1 = 1/9
        Player stays with B;  LOSS
        Player switches to C;  WIN
    Player picks door C;  P = 1/3 * 1/3 = 1/9
      Monty shows Door A;  P = 1/3 * 1/3 * 1/2 = 1/18
        Player stays with C;  WIN
        Player switches to B;  LOSS
      Monty shows Door B;  P = 1/3 * 1/3 * 1/2 = 1/18
        Player stays with C;  WIN
        Player switches to A;  LOSS
If your simulation does not conform with the mathematically derived result, your simulation is incorrect.

Re: Your iPhone just got less secure. Blame the FBI

#190

Post by chopin »

wolf550e wrote: post #144
tptacek wrote: post #120

Earlier quoted context omitted.

There is no such thing as "responsible disclosure". That's a term invented by vendors to coerce independent researchers into doing free work for them. Semantic drift has somewhat legitimized the term, but I think it's important we remember why it was conjured in the first place.

How would you call Google Project Zero's 90 day policy?

Doesn't Google do free work for the vendors with this project? I would assume so.
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