Https - How to generate crt and key files.

@ Change the current directory.
$ cd /usr/local/etc/nginx
$ mkdir ./ssl

@ Generate SSL key, crt files.[openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /usr/local/etc/nginx/ssl/nginx.key -out /usr/local/etc/nginx/ssl/nginx.crt]

$ openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /usr/local/etc/nginx/ssl/nginx.key -out /usr/local/etc/nginx/ssl/nginx.crt
Generating a 2048 bit RSA private key
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writing new private key to '/usr/local/etc/nginx/ssl/nginx.key'
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You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
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Country Name (2 letter code) [AU]:jp
State or Province Name (full name) [Some-State]:tokyo
Locality Name (eg, city) []:shibuya
Organization Name (eg, company) [Internet Widgits Pty Ltd]:ca
Organizational Unit Name (eg, section) []:test
Common Name (e.g. server FQDN or YOUR name) []:test.io
Email Address []:kim_woongjoon@cyberagent.co.jp

openssl: This is the basic command line tool for creating and managing OpenSSL certificates, keys, and other files.

req: This subcommand specifies that we want to use X.509 certificate signing request (CSR) management. The "X.509" is a public key infrastructure standard that SSL and TLS adheres to for its key and certificate management. We want to create a new X.509 cert, so we are using this subcommand.

-x509: This further modifies the previous subcommand by telling the utility that we want to make a self-signed certificate instead of generating a certificate signing request, as would normally happen.

-nodes: This tells OpenSSL to skip the option to secure our certificate with a passphrase. We need Nginx to be able to read the file, without user intervention, when the server starts up. A passphrase would prevent this from happening because we would have to enter it after every restart.

-days 365: This option sets the length of time that the certificate will be considered valid. We set it for one year here.

-newkey rsa:2048: This specifies that we want to generate a new certificate and a new key at the same time. We did not create the key that is required to sign the certificate in a previous step, so we need to create it along with the certificate. The rsa:2048 portion tells it to make an RSA key that is 2048 bits long.

-keyout: This line tells OpenSSL where to place the generated private key file that we are creating.

-out: This tells OpenSSL where to place the certificate that we are creating.