Logjam isn't the only reason your computer might be more vulnerable to internet threats

Logjam isn't the only reason your computer might be more vulnerable to internet threats
Cyber warning. Credit: Shutterstock

There's a hole in the protection surrounding some of the internet's supposedly secure websites. A group of researchers has discovered that cyber criminals and other hackers can attack websites that use the "https" security encryption using a method known as "Logjam". This attack, which is thought to work on around 8% of the top one million websites, allows hackers to see important information that should be protected, such as payment details or private communication.

Encryption is a way of turning information into a secret code in order to stop others from eavesdropping on your conversations. Every time you see a padlock or then letters "https" in the address bar of your web browser, everything being sent between your computer and the remote web server where the you are viewing is stored is encrypted and should be secret. The discovery of the Logjam attack, which is possible because of a flaw in the , means this may not always be the case.

Logjam works by attacking a part of the process called the "Diffie-Hellman key exchange". This is a way of creating and securely sending the key that unlocks the encryption and allows you to read the information. This key is formed using two very large, complex and random prime numbers (numbers that can only be divided by themselves or the number one), which cannot easily be predicted. The larger the key, the stronger the encryption.

Older keys are saved with 1024 bits of , meaning each one has 21024 possible combinations. But computers are now powerful enough to work out what the right combination is. The Logjam attack involves capturing the key data and then using computational power to crack its code. As a result, security experts are advising web sites that still use these keys to move to much longer versions that are harder to predict.

Hackers can also use something called a rainbow table to look up pre-cracked codes and use their computer to match the key against them. The more power a computer has, the faster it can work through the database of pre-cracked codes. There are still multiple combinations to check, but the work has in part already been done for them.

The growing power of computers means many existing security measures are increasingly likely to become obsolete and need replacing. However, it's not just companies failing to keep up with the latest advances that could leave internet users more vulnerable. Most technology companies are trying to create stronger security for their products because we (their customers) demand it. But there is also a trade-off between national security and personal security they have to be aware of.

Agencies such as the FBI have stated that some methods of encryption are now too strong, meaning they want to be able to peek at people's communications. They want encryption to be strong but not impenetrable. This has become a frustrating dilemma and, as Logjam proves by exploiting weaker Diffe-Hellman keys, there are weaker servers at the lower end that may fall foul of this demand to balance the security expectations of their organisation with the policing demands of governmental bodies.

There is already a flurry of activity across the internet as server administrators are attempting to patch the Logjam problem and increase their security level for key exchanges. We'll just have to hope that they can accomplish this before someone compromises their servers. While only a proportional minority of websites are affected by Logjam, you can also check your web browser and see if it needs updating.


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This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
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Citation: Logjam isn't the only reason your computer might be more vulnerable to internet threats (2015, May 25) retrieved 18 June 2019 from https://phys.org/news/2015-05-logjam-isnt-vulnerable-internet-threats.html
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May 25, 2015
Using prime numbers to seed encryption algorithms is not smart. There are a limited set of prime numbers, so the task of decrypting data is simplified, since all a hacker has to do to discover the seed is to match solutions against a limited data set consisting of only prime numbers. Obviously this is information intended to mislead. The government is engaged in a perpetual exercise in futility, that of trying to keep one step ahead in a game invented, played, and managed by others.

May 26, 2015
^^ baud, could you understand cryptography less?...
They don't just use primes, no... They use the multiple of 2 Very very large primes. if you don't use primes you can do a multi-layered attack, where you sequentially remove digits from the key by checking multiple devisors.
the pool of 'very large primes' is huge. logarythms, exponents are very processor intensive activities, and storing the rainbow tables for a 1024bit key would require all the space of every drive we've ever made as a species multiplied by few magnitude. solving them by random chance (checking 2 random primes, or every prime in order against all other possible primes up to 1024 bit) would take longer than the age of the universe to solve if we threw every processor we've ever made into it ON AVERAGE.

with 2 primes you can never tell how close you're getting, you can't target.
untill quantum computers destroy that notion.

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