Certificate Framework Overview

The certificate framework shields the differences between third-party certificate algorithm libraries. It provides the capabilities of parsing and validating a certificate, certificate extensions, and a certificate revocation list (CRL), and validating a certificate chain.

You can use the APIs provided by the certificate framework to easily complete your development.

NOTE The certificate framework provides the capabilities of processing certificates and CRL data, but does not provide the capabilities of generating or issuing certificates or CRLs. Certificates and CRLs are issued by a certificate authority (CA) rather than a single application.

Basic Concepts

The certificate framework provides APIs for parsing, serializing, signing an X.509 certificate, verifying the signature of an X.509 certificate, and operating X.509 CRLs and the certificate chain validator.

Before you get started, familiarity with the basic certificate concepts is helpful, which include but are not limited to the following:

  • Digital certificate
  • X.509 (also referred to as "X509" in this document)
  • Certificate chain
  • To Be Signed (TBS)
  • CRL

Certificate Specifications

The following describes certificate specifications.

Certificate Chain Validation

The certificate chain validator does not verify the certificate validity period because the device system time is always untrusted. To check the validity of a certificate, use checkValidityWithDate() of X509Cert.

Certificate Format

Currently, only the certificates in DER and PEM formats are supported.

X.509 Certificate Structure

Certificate example:

X.509 CRL Structure

CRL example:

Constraints

The certificate framework depends on the basic algorithm capabilities of the Crypto Architecture Kit, which does not support multi-thread concurrent operations. For details, see Constraints.

Development

You can use the certificate framework to implement the following functionalities. Before you start, be sure to familiarize yourself with Certificate Specifications.

The certificate framework provides the following classes.

Name Class Description
X.509 certificate X509Cert Provides APIs for parsing, serializing, and signing an X.509 certificate, verifying an X.509 certificate signature, and obtaining certificate information.
Certificate extension CertExtension Provides APIs for obtaining X.509 certificate extensions, such as CA and CRL distribution points.
X.509 CRL X509CRL Provides APIs for parsing and serializing an X.509 CRL, and obtaining X.509 CRL information.
Certificate chain validator CertChainValidator Provides APIs for validating a certificate chain (excluding the certificate validity period) and obtaining the certificate chain algorithm.
Certificate and CRL collection CertCRLCollection Provides APIs for obtaining information about the certificate and CRL collection.
X.509 certificate chain X509CertChain Provides APIs for obtaining the certificate list and validating a certificate chain.