LDPC Code Design Aspects for Physical-Layer Key Reconciliation

In this work, we investigate a physical-layer key reconciliation protocol for a reciprocal, flat fading channel between two legitimate users. We consider the scenario when the n bits of the secret key are measured independently by Alice and Bob without a transmission over the channel. Due to reciprocity, the generated keys are identical except for noise at both ends. We assume Gaussian noise and ignore non-ideal behavior of circuitry and alike. Redundancy information required to reconciliate the key is transmitted from one legitimate user to the other. LDPC codes are employed for the reconciliation procedure. The main focus of this work lies in designing the code structure through density evolution for a multi-edge-type description.