Encrypting as much web traffic as possible to prevent data theft and other tampering is a critical step toward building a safer, better Internet. We’re proud to be the first Internet performance and security company to offer SSL protection free of charge.
SSL (Secure Socket Layer) is the standard security technology for establishing an encrypted link between a web server and a browser. This secure link ensures that all data transferred remains private. It’s also called TLS (Transport Layer Security). Millions of websites use SSL encryption everyday to secure connections and keep their customer’s data safe from monitoring and tampering.
Every website on the Internet should be served over HTTPS. Here’s why:
Manually configuring SSL requires several steps, and a misconfiguration can prevent users from getting to your website. Cloudflare allows any Internet property to become HTTPS-enabled with the click of a button. You’ll never need to worry about SSL certificates expiring or staying up to date with the latest SSL vulnerabilities when you’re using Cloudflare SSL.
HTTPS isn’t what it used to be. It’s faster, more secure, and used by more websites than ever before. SSL enables HTTP/2, which has the potential to make websites up to two times faster with no changes to existing codebases. Modern TLS also includes performance-oriented features like session resumption, OCSP stapling, and elliptic curve cryptography that uses smaller keys (resulting in a faster handshake). TLS 1.3 reduces latency even further and removes insecure features of TLS making HTTPS more secure and performant than any previous version of TLS and its non-secure counterpart, HTTP.
Cloudflare has even worked to improve the performance of OpenSSL. We implemented ChaCha20-Poly1305, a cipher suite that runs three times faster than AES-128-GCM on mobile devices. We care about performance.
Cloudflare SSL operates in different modes depending on the level of security required and the amount of configuration you’re willing to do. Traffic to the end user will always be encrypted, which means your website will always enjoy the benefits of HTTPS. However, traffic between Cloudflare and your origin server can be configured in a variety of ways.
Flexible SSL encrypts traffic from Cloudflare to end users of your website, but not from Cloudflare to your origin server. This is the easiest way to enable HTTPS because it doesn’t require installing an SSL certificate on your origin. While not as secure as the other options, Flexible SSL does protect your visitors from a large class of threats including public WiFi snooping and ad injection over HTTP.
Full SSL mode provides encryption from end users to CloudFlare and from CloudFlare to your origin server. This requires an SSL certificate on your origin server. In Full SSL mode, you have three options for certificates to install on your server: one issued by a Certificate Authority (Strict), one issued by Cloudflare (Origin CA), or a self signed certificate. It is recommended that you use a certificate obtained through Cloudflare Origin CA.
Origin CA uses a Cloudflare-issued SSL certificate instead of one issued by a Certificate Authority. This reduces much of the friction around configuring SSL on your origin server, while still securing traffic from your origin to Cloudflare. Instead of having your certificate signed by a CA, you can generate a signed certificate directly in the Cloudflare dashboard.
Cloudflare automatically provisions SSL certificates that are shared by multiple customer domains. Business and Enterprise customers have the option to upload a custom, dedicated SSL certificate that will be presented to end users. This allows the use of extended validation (EV) and organization validated (OV) certificates.
PCI 3.2 compliance requires either TLS 1.2 or 1.3, as there are known vulnerabilities in all earlier versions of TLS and SSL. Cloudflare provides a “Modern TLS Only” option that forces all HTTPS traffic from your website to be served over either TLS 1.2 or 1.3.
Opportunistic Encryption provides HTTP-only domains that can't upgrade to HTTPS, due to mixed content or other legacy issues, the benefits of encryption and web optimization features only available using TLS without changing a single line of code.
Geo Key Manager provides the ability to choose which Cloudflare data centers have access to private keys in order to establish HTTPS connections. Cloudflare has preconfigured options to select from either US or EU data centers as well as the highest security data centers in the Cloudflare network. Data centers without access to private keys can still terminate TLS, but they will experience a slight initial delay when contacting the nearest Cloudflare data center storing the private key.
Supporting the HTTP Strict Transport Security (HSTS) protocol is one of the easiest ways to better secure your website, API, or mobile application. HSTS is an extension to the HTTP protocol that forces clients to use secure connections for every request to your origin server. CloudFlare provides HSTS support with the click of a button.
Automatic HTTPS Rewrites safely eliminates mixed content issues while enhancing performance and security by rewriting insecure URLs dynamically from known (secure) hosts to their secure counterpart. By enforcing a secure connection, Automatic HTTPS Rewrites enables you to take advantage of the latest security standards and web optimization features only available over HTTPS.
Cloudflare’s Mutual Auth (TLS Client Auth) creates a secure connection between a client, like an IoT device or a mobile app, and its origin. When a client attempts to establish a connection with its origin server, Cloudflare validates the device’s certificate to check it has authorized access to the endpoint. If the device has a valid client certificate, like having the correct key to enter a building, the device is able to establish a secure connection. If the device’s certificate is missing, expired, or invalid, the connection is revoked and Cloudflare returns a 403 error.
Dedicated SSL Certificates provide high-level encryption and compatibility, along with lightning fast performance, served through our global content distribution network. With a few clicks within the Cloudflare dashboard, you can easily and quickly issue new certificates, securely generate private keys and more. Dedicated SSL Certificates are available for purchase on all Cloudflare pricing plans. Learn More
Cloudflare engineers deal with billions of SSL requests on a daily basis, so when a new security vulnerability is discovered, we have to act fast. Many vulnerabilities don’t affect users due to our strict security standards, but we love explaining how encryption breaks.
In early 2016, we saw web client support for AEAD ciphers increase from under 50% to over 70% in only six months. Learn why cipher block chaining is no longer considered completely secure. Read more ›
Cloudflare customers were never affected by the Logjam vulnerability, but we did create a detailed writeup explaining how it works. Read more ›
Cloudflare encrypts all traffic between its datacenters using its own internal certificate authority. We built our own open-source PKI toolkit to do it. Read more ›
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Minimum Supported Browser Versions for Cloudflare SSL Free Users:
Note: Operating systems, when specified above, are the minimum version required. If you need more compatibility with older browsers, such as Windows XP SP2 and Android <3.0, please use the SSL on our Pro, Business, or Enterprise plans. If you have further questions please see our FAQ.