Monthly Archives: August 2016

Phone networks revealed

unduhan-40The encryption scheme used for second generation (2G) mobile phone data can be hacked within seconds by exploiting weaknesses and using common hardware, researches at Agency for Science, Technology and Research (A*STAR), Singapore, show. The ease of the attack shows an urgent need for the 2G Global System for Mobile Communications (GSM) encryption scheme to be updated.

GSM was first deployed 25 years ago and has since become the global standard for mobile communications, used in nearly every country and comprising more than 90 per cent of the global user base.

“GSM uses an encryption scheme called the A5/1 stream cipher to protect data,” explains Jiqiang Lu from the A*STAR Institute for Infocomm Research. “A5/1 uses a 64-bit secret key and a complex keystream generator to make it resistant to elementary attacks such as exhaustive key searches and dictionary attacks.”

Any encryption scheme can be hacked given sufficient time and data, so security engineers usually try to create an encryption scheme that would demand an unfeasible amount of time to crack. But, as GSM gets older, weaknesses in the A5/1 cipher and advances in technology have rendered GSM communications susceptible to attack.

Straightforward ‘brute force’ attacks by guessing the secret key from the data stream are still intensively time consuming, and although A5/1 was reported to have been successfully attacked in 2010, the details of the attack were kept secret. By exploiting weaknesses in the A5/1 cipher, Lu and his colleagues have now demonstrated the first real-time attack using a relatively small amount of data.

“We used a rainbow table, which is constructed iteratively offline as a set of chains relating the secret key to the cipher output,” says Lu. “When an output is received during an attack, the attacker identifies the relevant chain in the rainbow table and regenerates it, which gives a result that is very like to be the secret key of the cipher.”

Using two specific exploits, Lu’s team was able to reduce the effective complexity of the key to a level that allowed a rainbow table to be constructed in 55 days using consumer computer hardware, making possible a successful online attack, in most cases within just nine seconds.

Capture the crush in biological cells

“Biological processes that make life happen and cause diseases largely take place inside cells, which can be studied with microscopes and other techniques, but not in enough detail,” said Michael Feig, an MSU professor of biochemistry and molecular biology who led the research project. “Our research has revealed unprecedented details about what exactly takes place inside biological cells, and how proteins in particular behave in their natural environment.”

The team set out to examine whether the crowding in biological cells alters the properties of biological molecules and their ability to carry out their function. Armed with access to the “K computer,” a supercomputer housed at the RIKEN Advanced Institute for Computational Science in Kobe, Japan, the research team was able to conduct computer simulations that model the cellular interior of a bacterium, and show a detailed view of how the various molecular components interact in a very dense environment.

“Our computer simulations were not too far away from simulating an entire cell in full atomistic detail,” Feig said. “These simulations exceeding 100 million atoms are the largest simulations of this kind and are several orders of magnitude larger than what is typical research work today.”

The powerful computer simulation led to a discovery that some proteins may not be as stable in very dense environments, losing the structures necessary for biological function. The research also found that this cellular environment might bring proteins involved in related biological processes closer to each other, which would enhance the overall efficiency of the cell in converting food to energy.

“Proteins in cells are squeezed together like people in the Tokyo subway during rush hour, where the crush violates personal space. But for proteins this is sometimes more welcome than we thought,” Feig said.

A third major finding is that smaller molecules, such as those providing food and carrying energy, appear to be distracted by the many opportunities to interact with the larger proteins, affecting their biological function.

“This is a breakthrough achievement in understanding how the molecules that biochemists normally study interact in real life conditions,” said Thomas Sharkey, chair of the Department of Biochemistry and Molecular Biology at MSU. “It will provide critical insights that will be used by people working to cure cancer and other diseases that depend on the cellular processes that are now much better understood.”

But this is just the beginning of detailed whole-cell simulations, according to Feig.

“Future studies will aim to reach longer time scales, and to move towards larger and more complex cells, especially human cells, to better relate to human diseases,” Feig said.