Patent ID: 9306739
Filing Date: 2016-04-05
CPC Classification: H04L

Claim Text:
1. A communication process for sending a qubit message between first and second communicants using a quantum channel for obviating a faked-state attack by an eavesdropper, said qubit message composed of ensemble bits and transmitted as a plurality of photons into the quantum channel, each photon having a corresponding bit value, said process comprising: preparing three uniformly random bit strings each of length 4N by the first communicant to produce a first string R, a second string P and a third string U, where N is an integer corresponding to a number of the ensemble bits, said first string R represents raw key bit values, said second string P establishes a first eigenstate basis for the ensemble bits, and said third string U determines a first unitary operator ν to apply to the plurality of photons in the qubit message; preparing two uniformly random bit strings each of length 4N by the second communicant to produce a fourth string M and a fifth string V, where fourth string M that represents a second eigenstate basis for strong measure of the ensemble bits, and said fifth string V determines a second unitary operator υ to apply to the plurality of photons in the qubit message; broadcasting said second string P by the first communicant and said fourth string M by the second communicant; applying said first unitary operator υ to the plurality of photons to be sent by the first communicant; recording a first time-ordered weak measurement of polarization as a sixth string α by the first communicant; transmitting the plurality of photons that form the qubit message into the quantum channel by the first communicant to the second communicant; applying said second unitary operator υ to the plurality of photons received by the second communicant; recording a second time-ordered weak measurement of polarization by the second communicant as a seventh string β; recording a strong measurement of polarization by the second communicant as an eighth string D; segregating data that correspond to differing eigenstate bases between second and fourth strings P and M by the first communicant to truncate said first and sixth strings R and α, and thereby respectively produce ninth and tenth strings R broadcasting said ninth string R truncating said seventh and eighth strings β and D by the second communicant based on said differing eigenstate bases to thereby respectively produce eleventh and twelfth strings β calculating a first average of results from said eleventh string β comparing said first average to a statistical security threshold by the second communicant to determine satisfaction or failure of said first average as a first condition; and communicating said first condition by the second communicant to the first communicant, wherein for said first condition being unsatisfactory the protocol aborts, and otherwise; broadcasting said twelfth string D calculating a second average of results from said tenth string α comparing said second average to said statistical security threshold by the first communicant to determine satisfaction or failure of said second average as a second condition, wherein for said second condition being unsatisfactory the protocol aborts, and otherwise; segregating said data that correspond to agreeing eigenstate bases by the first communicant to truncate said first string R to produce a thirteenth string R