How to generate RSA public and private key pair in PKCS #8 format

This article explains how to create RSA public and private key pairs in PKCS#8 format.

This might be required if an upstream supplier asks you for the public in PKCS#8 format.

The key to achieving this is basically a three-step process:

1. Create key pair

openssl genrsa -out keypair.pem 2048

2. Extract public part

openssl rsa -in keypair.pem -pubout -out publickey.crt

At this point you have your public key called publickey.crt

3. Extract private part

openssl pkcs8 -topk8 -inform PEM -outform PEM -nocrypt -in keypair.pem -out pkcs8.key

At this point, you have your private key and it’s called pkcs8.key

Reference

https://stackoverflow.com/questions/44474516/how-to-create-public-and-private-key-with-openssl