Security and energy-consumptiont are two conflicting challenges in the design and operation of the smart cities that use Internet-of-Things (IoT). Providing power to IoT things (i.e., sensors and their communications) is a challenge as battery have a limited lifetime, and their maintenance and disposal are costly and hazardous. System on chip (SoC) power requirements for IoT ultra-low-power realm is different and is a challenge for the design engineers to provide uninterrupted power. In this paper, a paradigm shift research that addresses a secure self-sustainable solar-energy harvesting system (EHS) with a security mechanism is proposed. This design incorporates Physically Unclonable Functions (PUFs) for the security of EHS along with an aging sensor for recycled IC detection. The control unit monitors the computational load, recharging of the battery, and security mechanism. Capacitor value modulation (CVM) is used for impedance matching between solar cell and converter during maximum power point tracking (MPPT) to avoid quiescent power consumption. The existing resources of EHS used for designing the PUFs and aging sensor. The secure EHS is designed and fabricated in CMOS 90nm technology. The resulting output is in the range of 3-3.55 V with an input 1-1.5 V. The proposed EHS is consuming 22 μW of power, that satisfies the ultra-low-power requirements of IoT smart nodes.