The shared secret is either shared beforehand between the communicating parties , in which case it can also be called a pre-shared key , or it is created at the start of the communication session by using a key-agreement protocol , for instance using public-key cryptography such as Diffie-Hellman or using symmetric-key cryptography such as Kerberos .
The shared secret is either shared before parties start to communicate ; in this case it can also be called a pre-shared key . Or it is created at the start of the communication session by using a key-agreement protocol , for-instance using public-key cryptography such as Diffie-Hellman or using symmetric-key cryptography such as Kerberos .