Google's Certificate Transparency project fixes several structural flaws in the SSL certificate system, which is the main cryptographic system that underlies all HTTPS connections. These flaws weaken the reliability and effectiveness of encrypted Internet connections and can compromise critical TLS/SSL mechanisms, including domain validation, end-to-end encryption, and the chains of trust set up by certificate authorities. If left unchecked, these flaws can facilitate a wide range of security attacks, such as website spoofing, server impersonation, and man-in-the-middle attacks.
Certificate Transparency helps eliminate these flaws by providing an open framework for monitoring and auditing SSL certificates in nearly real time. Specifically, Certificate Transparency makes it possible to detect SSL certificates that have been mistakenly issued by a certificate authority or maliciously acquired from an otherwise unimpeachable certificate authority. It also makes it possible to identify certificate authorities that have gone rogue and are maliciously issuing certificates.
Because it is an open and public framework, anyone can build or access the basic components that drive Certificate Transparency. This is particularly beneficial to Internet security stakeholders, such as domain owners, certificate authorities, and browser manufacturers, who have a vested interest in maintaining the health and integrity of the SSL certificate system.
To learn more about Certificate Transparency, read the introductory documentation. If you're already familiar with the basic concepts of Certificate Transparency and you want to dive deeper into the implementation details, take a look at the detailed design documentation. We also have an open source project that shows you how to build some of the key components that drive the Certificate Transparency framework.