Fast Quantum Byzantine Agreement: Difference between revisions

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*<math>b_i:</math> input bit of player <math>i</math>
*<math>b_i:</math> input bit of player <math>i</math>
*<math>d:</math> the agreement value at the end of the protocol
*<math>d:</math> the agreement value at the end of the protocol
===Relevant Parameters===
The number of players <math>n</math> and the number of failures <math>t</math> are previously introduced parameters of the agreement protocol. The Quantum Oblivious Common Coin protocol has a single parameter <math>k</math> (used in the [[Verified Quantum Secret Sharing scheme]]), but it is unclear from the works [[Quantum Byzantine Agreement#References|(1), (3)]] how this influences the guarantees of the protocol. Also note that the fairness <math>p</math> of the Quantum Oblivious Common Coin is not a parameter, but rather a result of the specific implementation of the protocol. The global Byzantine Agreement protocol can then tolerate up to <math>t < \left \lfloor{pn}\right \rfloor </math>. The Quantum Oblivious Common Coin subroutine proposed by [[Quantum Byzantine Agreement#References|(3)]] has <math>p > \frac{1}{3}</math> (synchronous case, <math>p > \frac{1}{4}</math> asynchronous case).


==Hardware Requirements==
==Hardware Requirements==
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* tolerates <math>t \leq n/3</math> (synchronous) or <math>t \leq n/4</math> (asynchronous) Byzantine failures;
* tolerates <math>t \leq n/3</math> (synchronous) or <math>t \leq n/4</math> (asynchronous) Byzantine failures;
* reaches ''agreement'' (each player outputs the same bit) under the ''validity'' condition (the agreement value was proposed by at least one player) and is guaranteed to ''terminate eventually'' (infinite executions occur almost never - i.e. have probability measure zero).
* reaches ''agreement'' (each player outputs the same bit) under the ''validity'' condition (the agreement value was proposed by at least one player) and is guaranteed to ''terminate eventually'' (infinite executions occur almost never - i.e. have probability measure zero).
The Quantum Oblivious Common Coin subroutine has a single parameter <math>k</math> (used in the [[Verifiable Quantum Secret Sharing scheme]]), but it is unclear from the works [[Quantum Byzantine Agreement#References|(1), (3)]] how the parameter <math>k</math> influences the guarantees of the protocol. Also note that the fairness <math>p</math> of the Quantum Oblivious Common Coin is not a parameter, but rather a result of the specific implementation of the protocol. The global Byzantine Agreement protocol can then tolerate up to <math>t < \left \lfloor{pn}\right \rfloor </math> failures. The Quantum Oblivious Common Coin subroutine proposed by [[Quantum Byzantine Agreement#References|(3)]] has <math>p > \frac{1}{3}</math> (synchronous case, <math>p > \frac{1}{4}</math> asynchronous case).


==Pseudo Code==
==Pseudo Code==
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