RSA Security, which has a patent on the algorithm, offered a series of US$10,000 prizes for breaking ciphertexts encrypted with RC5, but these contests have been discontinued as of May 2007. A number of these challenge problems have been tackled using distributed computing, organised by Distributed.net. Distributed.net has brute-forced RC5 messages encrypted with 56- and 64-bit keys, and now is working on cracking a 72-bit key. At the current rate (as of November 12, 2008), it will take approximately 1,000 years to test every possible key to complete the project.