# cd /usr/local/apache/conf/ssl.key
# cp -p server.key server.key.org
# openssl rsa -in server.key.org -out server.key

# cd /usr/local/apache/conf/ssl.key/
# openssl rsa < server.key > server.key.out 
read RSA key
Enter PEM pass phrase: (パスフレーズを入力)
writing RSA key
# mv server.key server.key.org
# mv server.key.out server.key