ULTRA LOW POWER CORE FOR LIGHTWEIGHT ENCRYPTION

A processing unit and a method of operating a processing unit. In an embodiment, the processing unit comprises a SIMON block cipher for transforming plaintext data into encrypted data. A key expansion module generates and outputs one or more encryption keys; and the key expansion module includes a first series of adiabatic registers for holding key generation data values, and for using adiabatic switching to transmit the key generation data values through the first series of adiabatic registers. A round function module receives the plaintext data and the one or more encryption keys, encrypts the plaintext data to generate the encrypted data, and outputs the encrypted data; and the round function module includes a second series of adiabatic registers for holding encryption data, and for using adiabatic switching to transmit the encryption data through the second series of adiabatic registers.