  Quantum key distribution (QKD) and quantum message encryption protocols
promise a secure way to distribute information while detecting eavesdropping.
However, current protocols may suffer from significantly reduced eavesdropping
protection when only a subset of qubits are observed by an attacker. In this
paper, we present two quantum cryptographic protocols leveraging the quantum
Fourier transform (QFT) and show their higher effectiveness even when an
attacker measures only a subset of the transmitted qubits. The foremost of
these protocols is a novel QKD method that leverages this effectiveness of the
QFT while being more practical than previously proposed QFT-based protocols,
most notably by not relying on quantum memory. We additionally show how
existing quantum encryption methods can be augmented with a QFT-based approach
to improve eavesdropping detection. Finally, we provide equations to analyze
different QFT-based detection schemes within these protocols so that protocol
designers can make custom schemes for their purpose.
