Security Experts:

CloudFlare Introduces Keyless SSL

Content delivery network and web security provider CloudFlare has introduced a new feature that allows customers to take advantage of the company's solutions without ever having to hand over their private SSL keys.

Private SSL keys are highly sensitive because they can be leveraged by a malicious actor to spoof an organization's identity and intercept traffic. That is why, over the past two years, CloudFlare has been working on introducing keyless SSL.

The idea emerged after CloudFlare had a meeting in the fall of 2012 with representatives of a major bank, which at the time was targeted with distributed denial-of-service (DDoS) attacks by alleged Iranian hackers of the Izz ad-Din al-Qassam Cyber Fighters group.

"The bankers all acknowledged what they needed was a cloud-based solution that could scale to meet the challenges they faced. Unfortunately, since they needed to support encrypted connections, that meant the cloud-based solution needed to terminate SSL connections," Matthew Prince, the CEO and co-founder of CloudFlare, wrote in a blog post.

Losing an SSL key is considered a critical security event which, as Prince describes it, could turn into a "nightmare," and financial institutions can't afford to take such risk. CloudFlare has been working since the 2012 meeting with the bank representatives on finding a practical way of helping organizations benefit from the cloud without the need to take possession of their SSL keys.

One of CloudFlare's engineers came up with a solution by the next day, but it took two years to perfect the solution and make it secure, fast and scalable.

"To make it work, we needed to hold connections open between CloudFlare's network and agents running on our customers' infrastructure. Moreover, we needed to share data about crytographic sessions setup for a visitor between all the machines that could serve that visitor," Prince explained. "Making it work was one thing, making it fast was another. And, today, Keyless SSL clients are experiencing 3x+ faster SSL termination globally using the service than they were when they were relying only on on-premise solutions."

On Friday, CloudFlare security engineer Nick Sullivan published a blog post providing technical details on how they've managed to achieve keyless SSL.

"We’ve seen how private keys can be stolen, and investing in techniques to limit their exposure makes the Internet a safer place. Our review of Keyless SSL indicates the keys themselves do not leave your infrastructure, and a secure channel with CloudFlare both protects the communication and reduces the attack surface for your key," a spokesperson from NCC Group’s Cryptography Services group commented.

"One of the core principles of computer security is to limit access to cryptographic keys to as few parties as possible, ideally only the endpoints. Application such as PGP, Silent Circle, and now Keyless SSL implement this principle and are correspondingly more secure," Jon Callas and Phil Zimmermann of encrypted communications firm Silent Circle said in a joint statement.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.