How to build stronger password hashes? Hold a contest

A new contest proposes to spur innovation in hashing methods used to secure passwords and other sensitive data

In the password security arms race, the bad guys are winning. Once-sturdy cryptographic "hashing" algorithms -- pillars of online data security -- are proving vulnerable to brute force attacks that use souped-up hardware to make tens of billions of password guesses a second.

Now a new contest proposes to shake things up, spurring what some security and cryptography experts say is much-needed innovation in the tools and methods used to secure passwords and other sensitive data.

Put simply, hashing algorithms are used to turn a piece of sensitive information -- like your password -- into a different, but still unique value, referred to as a hash value or checksum that can be stored safely. For a party with the right information (the key used to create the hash value), the sensitive information can easily be reconstructed from its hash. Without the key, it should be impossible to figure out the original value from its hashed value.

Lately, however, the protections offered by hashing have been diminishing. Moore's Law means would-be password crackers with a modest budget can assemble a rig outfitted with superfast GPUs. The hardware coupled with free software like hashcat and expansive "rainbow tables" of known hashes and their corresponding cleartext values (also available for free, in many cases) make short work of any encrypted password collection. The tools have thrown open the door to everything from account takeovers to (potentially) spying by retailers and other commercial entities.

What's to be done? The Password Hashing Competition is the brainchild of a group of leading security and cryptography experts, including some leading figures in the online password cracking scene. They say a competition is the best way to spur new thinking in response to the arms race that has rendered once solid encryption technologies like MD5 obsolete.

The organizers include technologists and crypto experts from tech firms like Microsoft and Square, as well as government and academic researchers (NIST, Johns Hopkins) and noted password crackers, including Jeremi Gosney of Stricure Consulting Group and Jens Steube of the Hashcat Project.

Jean-Philippe Aumasson, the creator of the competition, said the contest has many goals. One is to suggest new cryptographic functions that could secure passwords and other sensitive data but be resistant to attack.

Aumasson said that any new algorithms that are highlighted by the Competition would still need to be vetted by experts before being adopted, but he noted that the process is the same used by standards groups like NIST. "NIST's SHA-3 competition had about four years between the initial publication and the selection of a winner," he said.

Another objective is to come up with ways to address poor hashing implementation. Behind the hacks and weak password security that make headlines is a tangle of problems, organizers say, including poor encryption algorithm choices and lack of expert guidance in how to properly deploy and configure encryption technology.

Not everyone is convinced that a competition to improve password hashing algorithms is the right idea. "While it's great to see focus on data protection through the lens of a competition, the issue isn't really about new algorithms," said Mark Bower, VP of product management and solutions architecture for Voltage Security. "Though algorithms used need to be proven and validated, NIST already has a process for that."

Faulty password handling implementations that use outdated hashing methods like MD5 or fail to appropriately "salt" (or randomize) hashes to prevent brute force attacks are a bigger problem, said Bower. "The result is password files which are relatively trivial to break after theft."

Aumasson agrees with that assessment. However, organizers say that even robust password hashing schemes have flaws that demand improvement: low memory requirements that facilitate cracking efforts, or complicated "nested" constructions in which multiple encryption algorithms are called in sequence. Besides, headlong advances in computing power may make even robust encryption algorithms and password encryption schemes subject to automated cracking, they say.

Aumasson said that the competition will also aim to improve hashing implementations. Noting the recent leak of Adobe passwords along with a database of password recovery hints for each account, Aumasson said that the hints allowed crackers to guess the weaker passwords and, from there, to find all users with the same password.

Submissions to the Password Hashing Competition are due by Monday, March 31. Organizers say they want proposals from any interested party. Submissions that comply with the submission requirements will be made available on the project's website.

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