このエラーメッセージに関する原因と対処に関して説明します。
エラーメッセージ(英語)：
pem permissions too open
対処
関連リンク
EC2にSSHで接続しようとしたら、秘密鍵のパーミッションエラーが出る
https://yuichon.com/2013/04/privatekey-permissions/
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SSHで接続しようとしたら秘密鍵のパーミッションでエラーが出た - yachibit.log
http://yachibit.hatenablog.jp/entry/2013/04/25/001912
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https://yoshinorin.net/2017/03/03/windows-filesystem-permission-and-bash-on-windows/
Windows SSH: Permissions for 'private-key' are too open - Super User
https://superuser.com/questions/1296024/windows-ssh-permissions-for-private-key-are-too-open