1. Extract the key-pair
openssl pkcs12 -in sample.pfx -nocerts -nodes -out sample.key
2. Get the Private Key from the key-pair
openssl rsa -in sample.key -out sample_private.key
3. Get the Public Key from key pair
openssl rsa -in sample.key -pubout -out sample_public.key
4. Need to do some modification to the private key -> to pkcs8 format
openssl pkcs8 -topk8 -inform PEM -in sample_private.key -outform PEM -nocrypt
Copy the output and save it as sample_private_pkcs8.key
5. Get those files
public key: sample_public.key
private key: sample_private_pkcs8.key
6. If you need base64 file run this command
openssl enc -base64 -in sample_public.key -out base64_public.key