*Updated on October 17, 2018 with details about changes in other browsers
TLS (Transport Layer Security) is the protocol which secures HTTPS. It has a long history stretching back to the nearly twenty-year-old TLS 1.0 and its even older predecessor, SSL. Over that time, we have learned a lot about how to build secure protocols.
TLS 1.2 was published ten years ago to address weaknesses in TLS 1.0 and 1.1 and has enjoyed wide adoption since then. Today only 0.5% of HTTPS connections made by Chrome use TLS 1.0 or 1.1. These old versions of TLS rely on MD5 and SHA-1, both now broken, and contain other flaws. TLS 1.0 is no longer PCI-DSS compliant and the TLS working group has adopted a document to deprecate TLS 1.0 and TLS 1.1.
In line with these industry standards, Google Chrome will deprecate TLS 1.0 and TLS 1.1 in Chrome 72. Sites using these versions will begin to see deprecation warnings in the DevTools console in that release. TLS 1.0 and 1.1 will be disabled altogether in Chrome 81. This will affect users on early release channels starting January 2020. Apple, Microsoft, and Mozilla have made similar announcements.
Site administrators should immediately enable TLS 1.2 or later. Depending on server software (such as Apache or nginx), this may be a configuration change or a software update. Additionally, we encourage all sites to revisit their TLS configuration. Chrome’s current criteria for modern TLS is the following:
- TLS 1.2 or later.
- An ECDHE- and AEAD-based cipher suite. AEAD-based cipher suites are those using AES-GCM or ChaCha20-Poly1305. ECDHE_RSA_WITH_AES_128_GCM_SHA256 is the recommended option for most sites.
- The server signature should use SHA-2. Note this is not the signature in the certificate, made by the CA. Rather, it is the signature made by the server itself, using its private key.
Over the coming Chrome releases, we will improve the DevTools Security Panel to point out deviations from these settings, and suggest improvements to the site’s configuration.