openssl create private key from public code example

Example 1: Command to create the private key using the openssl command :

openssl genrsa -out private.pem 2048

Example 2: Command to create the private key and public using the openssl command :

openssl genrsa -out private.pem 2048
openssl rsa -in private_key.pem -outform PEM -pubout public.pem