Cryptogenography

Brody, Joshua; Jakobsen, S.; Scheder, Dominik; Winkler, Peter

doi:10.1145/2554797.2554800

Cited by 7 publications

(26 citation statements)

References 11 publications

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“…Brody et al [4] studied the following cryptogenographic problem. We flip a coin, and tell the result to one out of n people.…”

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

“…We assume that both Frank and Eve make their guesses to maximise the probability that they win, rather than maximise the probability of being correct. 6 For n = 2, Brody et al [4] showed that the group would win with probability 1 3 but no protocol can ensure winning with probability above 3 8 . Doerr and Künnemann [12] later improved this upper bound to 0.3672 and the lower bound to 0.3384.…”

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

“…Doerr and Künnemann [12] later improved this upper bound to 0.3672 and the lower bound to 0.3384. For general values of n, Brody et al [4] showed that the probability that the group wins is always below 3/4 and for sufficiently high n it is at least 0.5644. In this section we will generalise the problem to a situation where more people are leaking and X contains more information.…”

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

“…We use the elimination strategy used in [4]. Let n > n and let π be a protocol for parameters h, l, n. We now construct a sequence of protocols π k for parameters h, l, n .…”

Section: Proposition 28 Succ(h L N) Is Non-decreasing In Nmentioning

confidence: 99%

“…Brody, Jakobsen, Scheder and Winkler [4] defined a game where a third option, "hinting at X ", is better. Here "hinting" means sending a message with a probability distribution which may or may not depend on the value of X .…”

Section: Introductionmentioning

confidence: 99%

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Information Theoretical Cryptogenography

Jakobsen

2016

J Cryptol

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Abstract.We consider problems where n people are communicating and a random subset of them is trying to leak information, without making it clear who are leaking the information. We introduce a measure of suspicion and show that the amount of leaked information will always be bounded by the expected increase in suspicion, and that this bound is tight. Suppose a large number of people have some information they want to leak, but they want to ensure that after the communication, an observer will assign probability at most c to the events that each of them is trying to leak the information. How much information can they reliably leak, per person who is leaking? We show that the answer is − log(1−c) c − log(e) bits.

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“…Brody et al [4] studied the following cryptogenographic problem. We flip a coin, and tell the result to one out of n people.…”

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

Section: The Original Cryptogenography Problemmentioning

confidence: 99%

“…We use the elimination strategy used in [4]. Let n > n and let π be a protocol for parameters h, l, n. We now construct a sequence of protocols π k for parameters h, l, n .…”

Section: Proposition 28 Succ(h L N) Is Non-decreasing In Nmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Information Theoretical Cryptogenography

Jakobsen

2016

J Cryptol

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The Two Sheriffs Problem: Cryptographic Formalization and Generalization

Sugimoto,

Nakai,

Watanabe

et al. 2023

Lecture Notes in Computer Science

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Information Theoretical Cryptogenography

Jakobsen

2014

Automata, Languages, and Programming

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We consider problems where n people are communicating and a random subset of them is trying to leak information, without making it clear who are leaking the information. We introduce a measure of suspicion, and show that the amount of leaked information will always be bounded by the expected increase in suspicion, and that this bound is tight. We ask the question: Suppose a large number of people have some information they want to leak, but they want to ensure that after the communication, an observer will assign probability ≤ c to the events that each of them is trying to leak the information. How much information can they reliably leak, per person who is leaking? We show that the answer is− log(e) bits. IntroductionThe year is 2084 and the world is controlled by a supercomputer called Eve. It makes the laws, carries them out, has surveillance cameras everywhere, can hear everything you say, and can break any kind of cryptography. It was designed to make a world that maximises the total amount of happiness, while still being fair. However, Eve started to make some unfortunate decisions. For example, it thought that to maximise the utility it has been designed to maximise, it must ensure that it survives, so it decided to execute everyone it knew beyond reasonable doubt was trying to plot against Eve (it was designed so it could not punish anyone as long as there is reasonable doubt, and reasonable doubt had been defined to be a 5% chance of being innocent). Everyone agrees that Eve should be shut down. The only person who can shut down Eve is Frank who is sitting in a special control room. Eve cannot hurt him, he has access to everything Eve can see, but he needs a password to shut down Eve. A small number of people, say 100 Londoners, know the password. Eve or Frank have no clue who they are, only that they exist. If one of them simply says the password, Eve will execute the person. So how can they reveal the password, without any of them getting killed? Suppose it is known that the password is the name of a museum in London. Frank then announces a date and time, and if you have the password, you show up at the correct museum that day and time, and if you do not have the information, you do as you would otherwise have done. If the museum is not too big, Frank will notice that there is one museum with more visitors than usual, so he gets the password. At the same time, if the museum is not too small, a large fraction of the visitors will just be there by chance, so Eve cannot punish any of them.1 If the password is not necessarily the name of a museum, Frank can simply define a one-to-one correspondence between possible passwords and museums (or, if there are many possible passwords, take one letter at a time, with different people leaking each letter). We do not actually need museums to use this idea, the important part is that many people sends some messages, that will follow a fixed distribution if they do not think about it, and that if they want to, they can choose a specific message. For example, ...

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Cryptogenography

Cited by 7 publications

References 11 publications

Information Theoretical Cryptogenography

Information Theoretical Cryptogenography

The Two Sheriffs Problem: Cryptographic Formalization and Generalization

Information Theoretical Cryptogenography

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