x.509 with OpenSSL

x509-cmd

# Generate root CA
openssl req -newkey rsa:2048 -nodes -keyout root-key.pem -x509 -days 365 -out root-ca.pem

# Generate leaf CSR
openssl req -new -newkey rsa:2048 -nodes -keyout leaf-key.pem -out leaf-csr.pem

# Generate leaf CA
openssl x509 -req -days 3650 -in leaf-csr.pem \
  -CA root-ca.pem -CAkey root-key.pem \
  -CAcreateserial -out leaf-ca.pem
  
# Read pem
openssl x509 -in cert.pem -text -noout

# Read key
openssl rsa -in mykey.key -text -noout

# Read CSR
openssl req -noout -text -in my.csr