- CA - Certificate Authority. CA is an entity that issues digital certificates for use by other parties. It is an example of a trusted third party. CAs are characteristic of many public key infrastructure (PKI) schemes.
- CSR - Certificate Signing Request. CSR is a message sent from an applicant to a certificate authority in order to apply for a digital identity certificate.
- PEM - Privacy-enhanced Electronic Mail. The .pem file name extension is used for a Base64-encoded X.509 certificate.
- CRT - The CRT extension is used for certificates.
DER - The DER extension is used for binary DER encoded.
req_extensions - declares request extensions to be included in PKCS #10 certificate signing request (CSR) objects.