Abstract:
With recent developments in quantum communications, much of the focus
has been put on development of di erent Quantum Key Distribution(QKD)
protocols that can successfully generate a symmetric key over insecure quan-
tum channel.
In this thesis, I have discussed in-depth security proof of a well known secure
protocol named as BB84 protocol. This simple version of proof was rst pro-
posed by Shor and Preskill[1], in year 2000. It involves two step derivation
of BB84 protocol from a 'Lo-Chau' protocol, which has already been proven
secure. I shall provide proof of exponentially lower bounds on mutual infor-
mation shared between sender/receiver and an adversary, therfore proving
its security.
Along with it, I have also introduced another varient of Lo-Chau protocol
which is more e cient in terms of shared resources, i.e. it uses almost 50%
lesser quantum states exchanged over channel. I shall also prove it to be
secure using the same technique used for BB84.
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