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This thesis explores the potential of using Received Signal Strength Indicators (RSSIs) as a Shared Secret Source for generating secret keys between two small IoT (Internet of Things) devices, notably for wearables and implantable medical devices. The main goal is to create an efficient algorithm, decreasing the computational cost required for key generation without compromising security. The algorithm consists of three main parts: preparing the data, quantizing the data into bits for key generation, and reconciling errors. The results suggest a promising potential for the use of RSSI as a shared source for secret key generation, with efficiency at a peak bit generation rate of 1.27 valid key bits per RSSI value for 64-bit keys with 8-bin quantization while blocking 97.6% of intrusion attempts. Future work for improving the results further includes exploring a narrower requirement for what values are to be used at the quantization stage as well as implementing a more sophisticated error reconciliation algorithm.