Practical Industrial Internet of Things Security

Symmetric keys

In symmetric key cryptography, the sender and receiver share a common secret to encrypt and decrypt messages. Unlike a password, in symmetric-key-based authentication, keys are not required to be sent between the parties at the time of the authentication event. The keys are usually established before a session is initiated using a public key algorithm. The key is sent either out-of-band, or ahead of time to the devices, encrypted using key encryption keys (KEK). Figure 3.4 shows the workflow involved in symmetric-key-based cryptography:

Figure 3.4: Event flow in Symmetric key cryptography

There are multiple symmetric encryption ...