The answer above is the correct answer because it is FALSE. Rijndael does not support multiples of 64 bits but multiples of 32 bits in the range of 128 bits to 256 bits. Key length could be 128, 160, 192, 224, and 256.
Both block length and key length can be extended very easily to multiples of 32 bits. For a total combination of 25 different block and key size that are possible.
The Rijndael Cipher Rijndael is a block cipher, designed by Joan Daemen and Vincent Rijmen as a candidate algorithm for the Advanced Encryption Standard (AES) in the United States of America. The cipher has a variable block length and key length.
Rijndael can be implemented very efficiently on a wide range of processors and in hardware.
The design of Rijndael was strongly influenced by the design of the block cipher Square.
The Advanced Encryption Standard (AES) The Advanced Encryption Standard (AES) keys are defined to be either 128, 192, or 256 bits in accordance with the requirements of the AES.
The number of rounds, or iterations of the main algorithm, can vary from 10 to 14 within the Advanced Encryption Standard (AES) and is dependent on the block size and key length. 128 bits keys uses 10 rounds or encryptions, 192 bits keys uses 12 rounds of encryption, and 256 bits keys uses 14 rounds of encryption.
The low number of rounds has been one of the main criticisms of Rijndael, but if this ever becomes a problem the number of rounds can easily be increased at little extra cost performance wise by increasing the block size and key length.
Range of key and block lengths in Rijndael and AES Rijndael and AES differ only in the range of supported values for the block length and cipher key length.
For Rijndael, the block length and the key length can be independently specified to any multiple of 32 bits, with a minimum of 128 bits, and a maximum of 256 bits. The support for block and key lengths 160 and 224 bits was introduced in Joan Daemen and Vincent Rijmen, AES submission document on Rijndael, Version 2, September 1999 available at http://csrc.nist.gov/ archive/aes/rijndael/Rijndael-ammended.pdf
AES fixes the block length to 128 bits, and supports key lengths of 128, 192 or 256 bits only.
Reference used for this question: The Rijndael Page and http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf and FIPS PUB 197, Advanced Encryption Standard (AES), National Institute of Standards and Technology, U.S. Department of Commerce, November 2001.