-----BEGIN label ----- … -----END label -----.
label include CERTIFICATE
CERTIFICATE REQUEST
PRIVATE KEY
X509 CRL *.pem (
*.cer (Certificates)
*.crt (also Certificates)
*.key (Public or private key) $ openssl genpkey -out the.key -algorithm RSA $ cat the.key -----BEGIN PRIVATE KEY----- MIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSkAgEAAoIBAQDd+IKR9wyKI5jp Yy4abfvcuDebil4av4P7qh1qykOZE5L0MYaAL0pXsC7iYu1/dZSGpqiR0xigwDFQ … -----END PRIVATE KEY-----
BEGIN RSA PRIVATE KEY is stored in a legacy format.