Embodiments include apparatuses, methods, and systems for generation of an encryption key. In various embodiments, an authentication circuit may include a first bank of spin-torque nano-oscillators (STNOs) including a plurality of STNOs to generate respective oscillation signals and a second bank of STNOs including a plurality of STNOs to generate respective oscillation signals. The authentication circuit may further include a key generation circuit to select a first oscillation signal from the plurality of oscillation signals associated with the first bank of STNOs and a second oscillation signal from the plurality of oscillation signals associated with the second bank of STNOs. The key generation circuit may generate an encryption key based on a frequency of the first oscillation signal and a frequency of the second oscillation signal.