Continuously charged isolated supply network for secure logic applications

#Secure systems, including encryption systems, are vulnerable to cryptographic attacks. Secret, cryptographic “keys” used to communicate information between intra-system components (and even extra-system components) and various other circuit operations can be determined by monitoring the power supply currents of the system as well as by way of complex mathematic means to deduce the secure information attributes. To prevent secure information from leaking to the integrated circuit power supply, it is necessary to isolate the secure logic in a way that prevents or greatly attenuates measurable indications of the energy required to operate the secure network.

#The energy required to operate the secure network is typically in the form of current impulses that charge or discharge node capacitance present at a logic gate output. Logic gates simply determine whether a node is pulled high (to the positive supply rail) or low (to the negative supply rail) dependent on the inputs to the logic gate. If a node is pulled high, then an impulse current from the positive supply is provided to charge the capacitance at that node to a high value. If a node is pulled low, then the charge present on the capacitor is discharged to the negative supply and is visible as a current impulse. These current impulses may be used by attackers to deduce secure information.

#This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

#FIG. 1A shows a high level schematic diagram of a continuously charged isolated supply system.

#FIG. 1B shows a network of continuously charged isolated supply systems.

#FIG. 2 shows a single ended equivalent circuit of a continuously charged secure system.

#A floating core network for secure isolation of a circuit from an external supply interface is described. The floating core network requires no special charge control or clocking networks. Instead, a control network provides AC (alternating) or pulsating isolation for the core, while for the DC (direct) component, the core is directly connected to the external supply. The information signal is greatly attenuated by the ratio of the information bandwidth to the control loop bandwidth.

#Through the described continuously charged isolated supply network, a core of logic cells and other circuit blocks can be secured for a variety of applications including cryptographic applications involving “crypto” or “cryptographic” blocks such as encryption blocks, authentication engines, hardware math accelerators, and coprocessors.

#Various implementations can reduce current components containing secure information, reduce or obscure circuit operational related information derivable from device current leakage, improve side channel immunity, and minimize power consumption.