generate rsa key.txt

Generating an SSH key
An SSH key consists of a pair of files. One is the private key, which should never be shared with anyone. 
The other is the public key. The other file is a public key which allows you to log into the containers and VMs you provision.
When you generate the keys, you will use ssh-keygen to store the keys in a safe location so you can bypass the login prompt when connecting to your instances.

To generate SSH keys in macOS, follow these steps:

Enter the following command in the Terminal window.

ssh-keygen -t rsa
This starts the key generation process. When you execute this command, the ssh-keygen utility prompts you to indicate where to store the key.

Press the ENTER key to accept the default location. The ssh-keygen utility prompts you for a passphrase.

Type in a passphrase. You can also hit the ENTER key to accept the default (no passphrase). However, this is not recommended.
Warning! You will need to enter the passphrase a second time to continue.

After you confirm the passphrase, the system generates the key pair.
The key's randomart image is:
+--[ RSA 2048]----+
|                 |
|         .       |
|        E .      |
|   .   . o       |
|  o . . S .      |
| + + o . +       |
|. + o = o +      |
| o...o * o       |
|.  oo.o .        |
+-----------------+
Your private key is saved to the id_rsa file in the .ssh directory
Never share your private key with anyone!

Your public key is saved to the id_rsa.pub;file
pbcopy < ~/.ssh/id_rsa.pub