Verifying the trustworthiness of Integrated Circuits (ICs) is of utmost importance, as hardware Trojans may destroy ICs bound for critical applications. A novel methodology combining on-chip structure with external current measurements is proposed to verify whether or not an IC is Trojan free. This method considers Trojans' impact on neighboring cells and on the entire IC's power consumption, and effectively localizes the measurement of dynamic power. To achieve this, we develop a new on-chip ring oscillator network structure distributed across the entire chip and place each ring oscillator's components in different rows of a standard-cell design. By developing novel statistical data analysis, the effect of process variations on the ICs' transient power will be separated from the effect of Trojans. Simulation results using 90nm technology and experimental results on Xilinx Spartan-6 FPGAs demonstrate the efficiency of our proposed method.