The original description of Rijndael cryptographic algorithm, the winner of the AES contest (Advanced Encryption Standard). Here some statements from the submission copyright and patent statement:
I, Joan Daemen, do hereby declare that to the best of my knowledge the practice of the algorithm, reference implementation, and mathematically optimized implementations, I have submitted, known as Rijndael may be covered by the followign U.S. and/or foreign patents: none. I do hereby declare that I am aware of no patent applications which my cover the practice of my submitted algorithm, reference implementation or mathematically optimized implementations.
See the AES homepage for more details.