openssl - generate private key and extract the public key from it

Generating a private RSA key

 

openssl genrsa -out privatekey.pem 2048

 

openssl rsa -in privatekey.pem -outform PEM -pubout -out publickey.pem

 

 

 

 

 

 

Generating a private EC key

 

openssl ecparam -name prime256v1 -genkey -noout -out key.pem

openssl ec -in key.pem -pubout -out public.pem