Synchronous Key Expansion for Implantable Device Encryption

The patent applies dynamics by implementing a key expansion mechanism that generates different encryption keys dynamically based on the message counter. Instead of using a static key, the system derives multiple keys from a master key through a key expansion function that processes the message counter, ensuring that each message is encrypted with a unique key. This dynamic key generation maintains strong security while avoiding the need for complex continuous key derivation operations.

The patent applies preliminary action by pre-expanding the master key into multiple derived keys before actual encryption occurs. The key expansion function is executed in advance to generate a sequence of keys based on the message counter, and these pre-computed keys are then used for encryption. This preliminary key expansion reduces the computational burden during message transmission, lowering power consumption while maintaining security.

The patent applies segmentation by dividing the encryption process into distinct functional components: a key expansion function that generates keys from a master key, and a cipher function that performs actual encryption. The key expansion function processes the message counter to derive multiple keys, while the cipher function uses these keys for encryption. This segmentation allows each component to be optimized independently, reducing overall computational complexity while maintaining security.

The patent applies parameter changes by varying the encryption key based on the message counter parameter. Instead of using a fixed key, the system changes the key parameter dynamically by processing the message counter through the key expansion function. This parameter variation introduces diversity in the encryption keys without requiring complex computational operations, as the key expansion function efficiently derives new keys from the counter value.