CloudFlare can provide its caching service without your SSL keys

CloudFlare said it has engineered a novel way to handle sensitive encryption keys that allows organizations such as financial institutions to still use its caching service to fend off cyberattacks.

The breakthrough, called “Keyless SSL,” is a new method for handling SSL (Secure Socket Layer) keys, which are used to encrypt content between a client and a service and are a fundamental defense to prevent intercepted data from being read by an attacker.

The company’s popular services protect websites from distributed denial-of-service and other attacks by using a network of global data centers to detect and filter attack traffic and keep websites online through extensive caching.

Websites using SSL could be accommodated by CloudFlare, but those operators had to turn over their SSL encryption keys. That’s risky, since the safety of the data is dependent on how well a third-party provider protects those keys.

If a bank’s SSL key is lost, for example, the incident is so serious that it must be reported to the Federal Reserve, wrote Matthew Prince, CloudFlare’s CEO, in a blog post on Thursday.

A stolen SSL key would allow attackers to decrypt traffic they’ve intercepted or set up a fake website that appears to be legitimate.

According to a technical writeup, Keyless SSL works like this: a person’s Web browser connects to the closest CloudFlare server and sends a bit of data, called a secret, that has been encrypted with a bank’s public SSL key.

CloudFlare’s server authenticates itself to a key server and sends its own encrypted secret, which the key server decrypts and sends it back over an encrypted tunnel. The shared secret is then used to connect the Web browser and the bank’s online service via CloudFlare.

One of the company’s edge nodes, or session server, does have to decrypt, inspect and re-encrypt the traffic before it goes back to the bank’s site, CloudFlare said.

Keyless SSL has been audited by iSEC Partners and Matasano Security, according to CloudFlare. The company will offer Keyless SSL initially for customers on its enterprise plan.

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