Cryptographers Break Commonly Used RC4 Cipher

Sparrowvsrevolution writes "At the Fast Software Encryption conference in Singapore earlier this week, University of Illinois at Chicago Professor Dan Bernstein presented a method for breaking TLS and SSL web encryption when it's combined with the popular stream cipher RC4 invented by Ron Rivest in 1987. Bernstein demonstrated that when the same message is encrypted enough times--about a billion--comparing the ciphertext can allow the message to be deciphered. While that sounds impractical, Bernstein argued it can be achieved with a compromised website, a malicious ad or a hijacked router." RC4 may be long in the tooth, but it remains very widely used.

Comments

Arcfour

[Hatta]

This is the cipher known as 'arcfour' in SSH. I use it regularly when speed is more important than security, which is frequently. I'm not sending a billion of the same files anywhere, so I will continue to use it.

Re:Arcfour

[Joce640k]

Oh, wait, it's the arcfour key scheduling thing again.

This is an old arcfour weakness, not news. Everybody knows about it (and how to avoid it). The SSL people just never bothered to do it.

Jokes on him!

[Kenja]

I always change my message after the 999,999,999th time I send it with the same encryption key.

Re:Oh, come on ... heh.

[bill_mcgonigle]

Anyone know what Cipher Suite configuration is the "safest" now? :)

You're screwed. You have the PCI people who are freaked out over CBC ciphers because of BEAST, you have lots of LTS distros not offering TLS 1.2, and you have people under FIPS who are your customers, so you wind up having to offer RC4 as a cipher to meet all of the above requirements. And even if you assume FIPS-managed clients will be controlling their ciphers to meet their internal requirements, you have to explain this to the PCI scanner vendor every. single. time.

If the LTS vendors could backport TLS 1.2, that would solve many headaches.