Feeds

Bulletproof quantum crypto dinged by implementation weakness

Trust but verify

Protecting against web application threats using SSL

Security researchers have identified possible weaknesses in quantum cryptography implementations. A team from Linköping University in Sweden has also come up with suggestions about how the attack could be blocked.

Quantum cryptography allows two users on an optical fibre network to exchange secret keys. It takes advantage of the particle-like nature of light. In quantum cryptography, each bit of the key is encoded upon a single light particle (photon). Intercepting this data randomly changes the polarisation of the light, irreversibly altering the data.

Because of this quantum mechanics effect, any attempt by an eavesdropper to determine a key corrupts the same key with noise. Quantum cryptography systems discard these corrupt keys and only use codes that are known to be secure. These quantum keys, once exchanged, can be used in a one-time pad.

The technology - long the stuff of cyberpunk novels and hi-tech spy stories - is leaving the laboratory and making its way into commercial markets, particularly in the banking sector.

The Swedish team's work does not undermine the principles that underpin quantum cryptography but rather highlight shortcomings in how systems are implemented in practice, a common source of cryptographic weaknesses. The potential weakness discovered by the Swedes involves how practical quantum cryptography systems authenticate that a received message has not been altered in transit.

Eavesdropping to obtain a quantum key isn't possible, as previously explained. But it may be possible to get clues about this quantum key. Using this information, practical quantum cryptography systems could be tricked into authenticating altered messages, the researchers warn in a paper published in the IEEE Transactions on Information Theory journal last month.

By accessing the quantum channel used in QC [quantum cryptography], the attacker can change the message to be authenticated. This, together with partial knowledge of the key, does incur a security weakness of the authentication. The underlying reason for this is that the authentication used, which is insensitive to such message changes when the key is unknown, becomes sensitive when used with a partially known key.

The research is largely based on a masters thesis by Jörgen Cederlof.

Jan-Åke Larsson, an associate professor of Applied Mathematics at Linköping University and one of the two principal authors of the study, told IT News Australia that adding a small number of random bits to the initial key exchange foils the attack, which he acknowledges would be tricky to pull off even without additional safeguards.

"We weren't expecting to find a problem in quantum cryptography but it is a really complicated system. The security of the current technology is not sufficient," Larsson said. "Authentication does not work as intended." ®

Reducing the cost and complexity of web vulnerability management

More from The Register

next story
Infosec geniuses hack a Canon PRINTER and install DOOM
Internet of Stuff securo-cockups strike yet again
'Speargun' program is fantasy, says cable operator
We just might notice if you cut our cables
Apple Pay is a tidy payday for Apple with 0.15% cut, sources say
Cupertino slurps 15 cents from every $100 purchase
Israeli spies rebel over mass-snooping on innocent Palestinians
'Disciplinary treatment will be sharp and clear' vow spy-chiefs
YouTube, Amazon and Yahoo! caught in malvertising mess
Cisco says 'Kyle and Stan' attack is spreading through compromised ad networks
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
Greater dev access to iOS 8 will put us AT RISK from HACKERS
Knocking holes in Apple's walled garden could backfire, says securo-chap
Microsoft to patch ASP.NET mess even if you don't
We know what's good for you, because we made the mess says Redmond
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Security and trust: The backbone of doing business over the internet
Explores the current state of website security and the contributions Symantec is making to help organizations protect critical data and build trust with customers.