# Calculating the Shared Secret

The shared secret SS facilitates secure communication between Bob and Alice:

1. An ephemeral key pair is created for the transaction.
2. Using Elliptic Curve Diffie-Hellman (ECDH), the shared secret SS is calculated as:

S=ePrivK⋅vpk

Where:

* ePrivK represents the ephemeral private key generated for the transaction.
* vpk is the recipient’s viewing public key.