generate self-signed certificate

openssl req -new -x509 -out cert.pem -keyout key.pem

create private key

openssl genrsa -out key.pem 2048

create private key with password protected

openssl genrsa -des3 -out key.pem 2048

generate self-signed certificate by key.pem

openssl req -new -x509 -key key.pem -out cert.pem -days 3650

create certificate request

openssl req -new -key key.pem -out cert.csr

view PEM certficate

openssl x509 -in cert.pem -inform pem -noout -text

view DER certficate

openssl x509 -in cert.der -inform der -noout -text