TechTarget

Companies forced to reconsider security as SHA-1 code is broken

A widely used method to secure online transactions and financial data using 160-bit encryption can be broken 2,000 times faster...

A widely used method to secure online transactions and financial data using 160-bit encryption can be broken 2,000 times faster than previously thought.

Security researchers at Shandong University in China reported last week that the SHA-1 encryption method can be cracked in days. It was previously thought the code would take decades to break.

This revelation will mean security managers will need to re-evaluate their companies' underlying encryption software.

SHA-1 is a means of scrambling information by creating a string of 160 characters - a hash - which adds a unique fingerprint to a message. This unique identifier makes the code effectively unbreakable.

Richard Brain, technical director at security consultancy Procheckup, said SHA-1 was deployed in nearly every secure electronic transaction, including single socket layer (SSL) for websites and SSH for encoding secure telnets and e-mails, and in some instances for validating ATM transactions.

The researchers found that SHA-1 is not "collision-free", meaning it is possible for code crackers to find two messages with the same hash value and use them to crack the code quickly.

Even so, the researchers said it would take a powerful supercomputer to achieve this. But by extrapolating Moore's Law, which predicts that computing power will double every 18 months, at some point in the future this level of computational power would be readily available.

Cryptography expert Bruce Schneier, chief technology officer at Counterpane Internet Security, said, "This attack builds on previous attacks on SHA-0 and SHA-1, and is a major, major cryptanalytic result. It pretty much puts a bullet into SHA-1 as a hash function for digital signatures.

"It is time for us all to migrate away from SHA-1," he added, but said, "Jon Callas, [security firm] PGP's CTO, put it best, 'It is time to walk, but not run, to the fire exits. You do not see smoke, but the fire alarms have gone off'."

Security firm RSA recommended firms use applications based on a newer hash function, SHA-256, rather than SHA-1. Burt Kaliski, chief scientist at RSA Laboratories, said, "The results certainly underscore the importance of designing systems with a flexible rather than a fixed choice of algorithm."

David Lacey, director, information security at Royal Mail Group, said, there is "no need to panic.If this is correct, then the algorithm is weaker but still fit for purpose." 

ID cards are a waste, says Schneier >>

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