$ cd ~/.ssh

ssh-keygen -t rsa

下記のようにパスワード3回入力

Generating public/private rsa key pair.

Enter file in which to save the key (/Users/XXX/.ssh/id_rsa): 【パスワード】

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in 【パスワード】.

Your public key has been saved in 【パスワード】.pub.

The key fingerprint is:

SHA256:【パスワード】

 XXX@XXX.local

The key's randomart image is:

■パスワード入力しないとid_rsa.pubが作成される
$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/Users/XXX/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /Users/XXX/.ssh/id_rsa.

Your public key has been saved in /Users/XXX/.ssh/id_rsa.pub.

The key fingerprint is:

■公開鍵確認

$ cat ~/.ssh/id_rsa.pub

■参考URL