How to create a private key

To create a RSA private key,

you can use the following command:

openssl genrsa -des3 -out privkey.pem 2048

To create a DSA private key,

you can use the following commands:

openssl dsaparam -out dsaparam.pem 2048

openssl gendsa -des3 -out privkey.pem dsaparam.pem

Reference:
https://www.openssl.org/docs/HOWTO/keys.txt