Mozilla’s Common CA Database (CCADB) promotes Transparency and Collaboration

The Common CA Database (CCADB) is helping us protect individuals’ security and privacy on the internet and deliver on our commitment to use transparent community-based processes to promote participation, accountability and trust. It is a repository of information about Certificate Authorities (CAs) and their root and subordinate certificates that are used in the web PKI, the publicly-trusted system which underpins secure connections on the web. The Common CA Database (CCADB) paves the way for more efficient and cost-effective management of root stores and helps make the internet safer for everyone. For example, the CCADB automatically detects and alerts root store operators when a root CA has outdated audit statements or a gap between audit periods. This is important, because audit statements provide assurance that a CA is following required procedures so that they do not issue fraudulent certificates.

Through the CCADB we are extending the checks and balances on root CAs to subordinate CAs to provide similar assurance that the subordinate CAs are not issuing fraudulent certificates. Root CAs, who are directly included in Mozilla’s program, can have subordinate CAs who also issue SSL/TLS certificates that are trusted by Firefox. There are currently about 150 root certificates in Mozilla’s root store, which leads to over 3,100 subordinate CA certificates that are trusted by Firefox. In our efforts to ensure that all subordinate CAs follow the rules, we require that they be disclosed in the CCADB along with their audit statements.

Additionally, the CCADB is making it possible for Mozilla to implement Intermediate CA Preloading in Firefox, with the goal of improving performance and privacy. Intermediate CA Preloading is a new way to hande websites that are not properly configured to serve up the intermediate certificate along with its SSL/TLS certificate. When other browsers encounter such websites they use a mechanism to connect to the CA and download the certificate just-in-time. Preloading the intermediate certificate data (aka subordinate CA data) from the CCADB avoids the just-in-time network fetch, which delays the connection. Avoiding the network fetch improves privacy, because it prevents disclosing user browsing patterns to the CA that issued the certificate for the misconfigured website.

Mozilla created and runs the CCADB, which is also used and contributed to by Microsoft, Google, Cisco, and Apple. Even though the common CA data is shared, each root store operator has a customized experience in the CCADB, allowing each root store operator to see the data sets that are important for managing root certificates included in their program.


  • Makes root stores more transparent through public-facing reports, encouraging community involvement to help ensure that CAs and subordinate CAs are correctly issuing certificates.
    • For example the website combines information from the CCADB and Certificate Transparency (CT) logs to identify problematic certificates.
  • Adds automation to improve the level and accuracy of management and rule enforcement. For example the CCADB automates:
  • Enables CAs to provide their annual updates in one centralized system, rather than communicating those updates to each root store separately; and in the future will enable CAs to apply to multiple root stores with a single application process.

Maintaining a root store containing only credible CAs is vital to the security of our products and the web in general. The major root store operators are using the CCADB to promote efficiency in maintaining root stores, to improve internet security by raising the quality and transparency of CA and subordinate CA data, and to make the internet safer by enforcing regular and contiguous audits that provide assurances that root and subordinate CAs do not issue fraudulent certificates. As such, the CCADB is enabling us to help ensure individuals’ security and privacy on the internet and deliver on our commitment to use transparent community-based processes to promote participation, accountability and trust.