4. In the key change operation of 20.15.7 Key Changes, suppose the manager simply transmitted delta2...

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4. In the key change operation of 20.15.7 Key Changes, supposethe manager simply transmitted delta2 = oldkey XOR newkey to theagent.
Suppose an eavesdropper discovers delta2 and also knows a fewbits of oldkey. What can the eavesdropper learn about newkey? Wouldthe same vulnerability apply to the mechanism of 20.15.7 KeyChanges?
Suppose an eavesdropper later discovers newkey. Explain how torecover oldkey, and why this does not work when the mechanism of20.15.7 Key Changes is used.

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Principle behind the proposed quantum cryptography protocol Thefinal single bit value is calculated from many bits through a pairof numbers ij announced by the receiver Bob The upper panelcorresponds to the actual scheme in which Bob measures thewavelike nature of the received light sent by Alice to learn thefinal bit value Notice that the value of ij might be controlledby an eavesdropper Eve through the signal II fed to Bobsmeasurement process M so looking at this panel alone the securityis ambiguous If Bob now measures the particlelike nature of thereceived light he no longer learns the final bit but can stillexactly produce the same pair ij Lower panel Here it is seenthat ij is directly randomized by the random number generatorTherefore the possibility that Bob could have measured theparticlelike nature of the received light ensures that therandomness of ij is not rigged by Eve Credit ToshihikoSasakCryptography the art and science of providing securecommunications typically employs three methods to authenticateusers and prevent data theft secret key See Answer

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