  When analysing Quantum Key Distribution (QKD) protocols several metrics can
be determined, but one of the most important is the Secret Key Rate. The Secret
Key Rate is the number of bits per transmission that result in being part of a
Secret Key between two parties. There are equations that give the Secret Key
Rate, for example, for the BB84 protocol, equation 52 from [1, p.1032] gives
the Secret Key Rate for a given Quantum Bit Error Rate (QBER). However, the
analysis leading to equations such as these often rely on an Asymptotic
approach, where it is assumed that an infinite number of transmissions are sent
between the two communicating parties (henceforth denoted as Alice and Bob). In
a practical implementation this is obviously impossible. Moreover, some QKD
protocols belong to a category called Asymmetric protocols, for which it is
significantly more difficult to perform such an analysis. As such, there is
currently a lot of investigation into a different approach called the
Finite-key regime. Work by Bunandar et al. [2] has produced code that used
Semi-Definite Programming to produce lower bounds on the Secret Key Rate of
even Asymmetric protocols. Our work looks at devising a novel QKD protocol
taking inspiration from both the 3-state version of BB84 [3], and the
Twin-Field protocol [4], and then using this code to perform analysis of the
new protocol.
