[root@centos ~]# cd /etc/pki/tls/certs
[root@centos certs]# openssl genrsa -des3 -out server.key 2048
Generating RSA private key, 2048 bit long modulus
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e is 65537 (0x10001)
Enter pass phrase for server.key: ←パスフレーズ入力
Verifying - Enter pass phrase for server.key: ←パスフレーズ再入力