ssh Github

Mac from Terminal

ssh-keygen -t ed25519 -C "yourmail@domain.com"

output:

Generating public/private ed25519 key pair.
Enter file in which to save the key (/Users/<xxxxx>/.ssh/<yyyy>): /Users/<xxxxx>/.ssh/github_id 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /Users/<xxxxx>/.ssh/github_id
Your public key has been saved in /Users/<xxxxx>/.ssh/github_id.pub
The key fingerprint is:
.....
The key's randomart image is:
+--[ED25519 256]--+
|    ..   .=..    |
|     .o  ..S..   |
|     ..  ..o. . .|
|  . o. ..o . . o |
|   =+...S = . +  |
|  oS.++  o + .   |
|    o+.+    . o  |
|      o..    . . |
|       o..E      |
+----[SHA256]-----+

go to https://github.com/settings/keys

click to New SSH Key

write a title, select Authentication Key, copy content of <yyyy>.pub file to the Key area