Authorities, powered by
step-ca, are the foundation of the Smallstep Platform and provide core certificate signing and management functions (issue, renew, and revoke certificates).
Authorities are used to issue and sign certificates and can run at any level of the PKI trust chain.
- Root CA - At the bottom of the PKI trust chain is the root authority.
Typically, a Root CA is only invoked to sign intermediate CA certificates.
This indirection allows for redundant topologies and facilitates migrations.
It also means root CA private keys can be managed, stored, and accessed with more care.
For the most security-sensitive use cases root signing keys can even be kept offline in a physically secure environment.
- Intermediate CA - Automated certificate management requires an online CA with an API that's capable of authenticating certificate signing requests (CSRs) and issuing certificates.
An intermediate CA is used to sign and issue certificates for devices, people, workloads, or whatever else you need to identify.
- Registration Authority - Not a certificate signer, a Registration Authority accepts and verifies certificate requests.
Upon verification, certificate signing requests are passed to an Intermediate CA or Root CA to sign and catalog.
Registration Authorities are useful for connecting remote sites to a central set of signing authorities.
Authorities are an open-source feature.
The best way to learn about Authorities is to create one for yourself.
Follow the instructions on the
step-ca getting started page and you will have your own Authority in no time at all.