A method for authenticating a device in a system using electrical properties of the device, the method comprising: receiving, by an authenticator, from a requestor (414, 1104), a plurality of input seed values; generating, by the authenticator, for each input seed value, load stimuli to produce an electrical load sequence on a power delivery network (100, 1112) of the device, each electrical load sequence relating to at least one magnitude and phase component in a specific frequency band; generating, by a load stimuli unit of the authenticator, said each electrical load sequence from the load stimuli; measuring, using one or more sensors (402 1, 402 2,... 402 N; 1118) located on the power delivery network (100, 1112) of the device, noise induced in the power delivery network (100, 1112) of the device in response to each electrical load sequence; determining, by the authenticator, from the measured induced noise, a dynamic response of the power delivery network (100, 1112) of the device corresponding to each input seed value, each dynamic response including at least one magnitude and phase component in a specific frequency band; generating, by the authenticator, from each dynamic response of the power delivery network (100, 1112) of the device, an authentication response value, each authentication response value relating to at least one magnitude and phase component in the specific frequency band corresponding to the dynamic response; transmitting, by the authenticator, to the requestor (414, 1104), the authentication response values; and comparing, by the requestor (414, 1104), the authentication response values to expected authentication response values to authenticate the device. receiving, by an authenticator, from a requestor (414, 1104), a plurality of input seed values; generating, by the authenticator, for each input seed value, load stimuli to produce an electrical load sequence on a power delivery network (100, 1112) of the device, each electrical load sequence relating to at least one magnitude and phase component in a specific frequency band; generating, by a load stimuli unit of the authenticator, said each electrical load sequence from the load stimuli; measuring, using one or more sensors (402 1, 402 2,... 402 N; 1118) located on the power delivery network (100, 1112) of the device, noise induced in the power delivery network (100, 1112) of the device in response to each electrical load sequence; determining, by the authenticator, from the measured induced noise, a dynamic response of the power delivery network (100, 1112) of the device corresponding to each input seed value, each dynamic response including at least one magnitude and phase component in a specific frequency band; generating, by the authenticator, from each dynamic response of the power delivery network (100, 1112) of the device, an authentication response value, each authentication response value relating to at least one magnitude and phase component in the specific frequency band corresponding to the dynamic response; transmitting, by the authenticator, to the requestor (414, 1104), the authentication response values; and comparing, by the requestor (414, 1104), the authentication response values to expected authentication response values to authenticate the device.