The Secretary of Commerce approves FIPS 197, Advanced Encryption Standard (AES), and makes it compulsory and binding on Federal agencies for the protection of sensitive, unclassified information. A new robust encryption algorithm was needed to replace the aging Data Encryption Standard (FIPS 46-3), which had been developed in the 1970s. In September 1997, NIST issued a Federal Register notice soliciting an unclassified, publicly disclosed encryption algorithm that would be available royalty-free worldwide. Following the submission of 15 candidate algorithms and three publicly held conferences to discuss and analyze the candidates, the field was narrowed to five candidates. NIST continued to study all available information and analyses about the candidate algorithms, and selected one of the algorithms, the Rijndael algorithm, to propose for the AES.