# Use Cases

## Self-protection With Key K

* **Alice** encrypts plaintext _P_ with key _K_.
  * **A**:C = {_P_}_k_
* **Alice** decrypts cryptogram _C_ with key _K_.
  * **A**:P' = {_C_}_k_
* _**P**_' should be equal to _P_ (requires checking).

<figure><img src="https://3450804385-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FRIg06sTkCh60KyuJiT39%2Fuploads%2Fa2hStsVhEs4wHxgJRICY%2F2023-09-15_21-58.png?alt=media&#x26;token=3c9c9e73-30d2-4306-aa82-1f00e5120d6c" alt=""><figcaption></figcaption></figure>

Secure communication with key _K_

* **Alice** encrypts plaintext _P_ with key _K_.
  * **A**:C = {_P_}_k_
* **Bob** decrypts _C_ with key _K_.
  * **B**:P' = {_C_}_k_
* _**P**_' should be equal to _P_ (requires checking).

<figure><img src="https://3450804385-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FRIg06sTkCh60KyuJiT39%2Fuploads%2FN829Hcj6NKi2TcIh0AFD%2F2023-09-16_09-51.png?alt=media&#x26;token=f3c5da8a-c82a-4d35-82f7-e4e2f3b7dfd0" alt=""><figcaption></figcaption></figure>
