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The Advanced Encryption Standard: A Status Report



Elizabeth B. Lennon


In 1997, the National Institute of Standards and Technology (NIST) initiated a process to select a symmetric-key encryption algorithm to be used to protect sensitive (unclassified) Federal Information, in furtherance of NIST's statutory responsibilities. In 1998, NIST announced the acceptance of fifteen candidate algorithms and requested the assistance of the cryptographic research community in analyzing the candidates. This analysis included an initial examination of the security and efficiency characteristics for each algorithm. NIST has reviewed the results of this research and selected five algorithms (MARS, RC6, Rijndael, Serpent and Twofish) as finalists. The research results and rationale for the selection of the finalists are documented in this report. The five finalists will be the subject of further study before the selection of one or more of these algorithms for inclusion in the Advanced Encryption Standard.
ITL Bulletin -


advanced encryption standard (AES), cryptanalysis, cryptographic algorithms, cryptography, encryption


Lennon, E. (1999), The Advanced Encryption Standard: A Status Report, ITL Bulletin, National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 13, 2024)
Created August 25, 1999, Updated February 19, 2017