Why Diffie–Hellman Encryption May Be Past Its Prime

October 21, 2015 @ 6:15 PM
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2 min read

The Diffie–Hellman key exchange has been a standard and successful approach to cryptography for some time. But security researchers say it’s now becoming vulnerable enough that organizations should start considering alternative forms of encryption.

In a paper titled “Imperfect Forward Secrecy: How Diffie–Hellman Fails in Practice,” University of Pennsylvania computer science experts outlined how the key exchange could be easily exposed to cybercriminals with sufficient resources and expertise. Also known as 1024-bit encryption, Diffie–Hellman was called out earlier this year as one of the problems associated with the Logjam vulnerability that put countless websites at risk.

The researchers told Network World that while moving to elliptic curve cryptography might be one solution, enterprises may face a significant challenge in just identifying all the places where Diffie–Hellman is used across their networks. Firms may also risk incompatibilities in application if they merely disable 1024-bit encryption. This is despite the fact that the National Institute of Standards and Technology (NIST) had suggested companies should have moved to a new form of cryptography by 2010.

According to Ars Technica, CISOs and their teams may not have to worry about Diffie–Hellman being exploited by everyday attackers. The research paper suggests it would take an enormous investment — think hundreds of millions of dollars — by the NSA or a similar organization to break the key exchange. That being said, the payoff could be massive, with those who bypass 1024-bit encryption having the power to listen in on connections that number in the trillions.

In some respects, cracking Diffie–Hellman sounds like something out of the movies. In fact, The Register compared it to the famous Enigma cryptanalysis during World War II that was captured in last year’s film “The Imitation Game.”

Truth may be stranger than fiction, though: The research paper suggested that because so many organizations use a hard-coded prime, cracking the encryption through one compute-intensive hack could trigger massive repercussions. Although it may shock people to learn that major organizations would take advantage of such an opportunity, that may be the least of worries if well-financed and highly technical cybercriminals do the same thing.

Shane Schick
Writer & Editor
Shane Schick is a contributor for SecurityIntelligence.