[1] For each contest, RSA had posted on its website a block of ciphertext and the random initialization vector used for encryption.
The name RC5-w/r/b indicates that the cipher used w-bit words, r rounds, and a key made up of b bytes.
[2] The contests are associated with the distributed.net group, which had actively participated in the challenge by making use of distributed computing to perform a brute force attack.
The recovered plaintext was: The unknown message is: It's time to move to a longer key length.
It took the group 1,757 days to locate the key, revealing the plaintext: The unknown message is: Some things are better left unread.