The Advanced Encryption Standard (Rijndael) block cipher requirements regarding keys and block
sizes have now evolved to which configuration?
A.
Both the key and block sizes can be 128, 192, and 256 bits each.
B.
The block size is 128 bits, and the key size is 128 bits.
C.
The key size is 128 bits, and the block size can be 128, 192, or 256 bits.
D.
The block size is 128 bits, and the key can be 128, 192, or 256 bits.
Explanation:
AES is comprised of the three key sizes, 128, 192, and 256 bits with a fixed block size of 128 bits. The
Advanced Encryption Standard (AES) was announced on November 26, 2001 , as Federal Information
Processing Standard Publication (FIPS PUB 197). FIPS PUB 197 states that This standard may be used
by Federal departments and agencies when an agency determines that sensitive (unclassified)
information (as defined in P.L. 100-235) requires cryptographic protection. Other FIPS-approved
cryptographic algorithms may be used in addition to, or in lieu of, this standard. Depending upon
which of the three keys is used, the standard may be referred to as AES-128, AES-192 or AES-256.
The number of rounds used in the Rijndael cipher is a function of the key size as follows: 256-bit key
14 rounds 192-bit key 12 rounds 128-bit key 10 rounds Rijndael has a symmetric and parallel
structure that provides for flexibility of implementation and resistance to cryptanalytic attacks.
Attacks on Rijndael would involve the use of differential and linear cryptanalysis.