RC5-64 broken in 1,757 days

Slashdot has just announced that RC5-64, RSA"s 64 bit encryption challenge has been broken.

On 14-Jul-2002, a relatively characterless PIII-450 in Tokyo returned the winning key to the distributed.net keyservers.

The key 0x63DE7DC154F4D03 produces the plaintext output:

The unknown message is: some things are better left unread

Unfortunately, due to breakage in scripts (dbaker"s fault, naturally) on the keymaster, this successful submission was not automatically detected. It sat undiscovered until 12-Aug-2002. The key was immediately submitted to RSA Labs and was verified as the winning key.

So, after 1,757 days and 58,747,597,657 work units tested the winning key was found! While it"s debatable that the duration of this project does much to devalue the security of a 64-bit RC5 key by much, we can say with confidence that RC5-64 is not an appropriate algorithm to use for data that will still be sensitive in more than several years" time.

On the distributed computing front, however, the RC5-64 project clearly demonstrates the viability of long-term, volunteer-driven, internet-based collaborative efforts. The next time someone bemoans the public"s short attention span or need for instant gratification you should remind them what 331,252 people were able to accomplish by joining together and working for nearly five years.

distributed.net"s RC5-64 project clearly shows that even the most ambitious projects can be completed by volunteers thanks to the combined power of the internet and distributed computing.

News source: distributed.net Press Release - RC5-64 has been solved!