Encryption/decryption system and key scheduler with variable key length

A system for encrypting or decrypting data, the system comprising:

• a controller;
• a processor;
• and
• a key scheduler;
• wherein the controller is adapted to control the processor and the key scheduler, the processor is adapted to encrypt or decrypt data based on an encryption or decryption key generated by the key scheduler, and the key scheduler further includes,
• a key storage unit for receiving and storing calculation key data items or storage key data items as input key data items in response to load enable signals and a clock signal and outputting the stored input key data items as the storage key data items,
• a key calculating unit for calculating the storage key data items and outputting the calculation key data items as a calculation result in response to calculation control signals, and
• a key output unit for selecting parts of the input key data items and the storage key data items in response to output control signals for each round, and outputting the selected parts as an encryption round key or a decryption round key, wherein the key storage unit includes,
• load enable circuits for outputting the calculation key data items or the storage key data items as the input key data items in response to the load enable signals;
• and
• registers for storing the input key data items received from the load enable circuits in response to the clock signal and outputting the stored input key data items as the storage key data items, wherein a total size of registers is greater than a size of the encryption round key or the decryption round key output from the key output unit for each round.