350-701 · Question #70
Which two key and block sizes are valid for AES? (Choose two.)
The correct answer is C. 128-bit block size, 192-bit key length D. 128-bit block size, 256-bit key length. Advanced Encryption Standard (AES) supports a fixed block size of 128 bits and key lengths of 128, 192, or 256 bits.
Question
Which two key and block sizes are valid for AES? (Choose two.)
Exhibit
Options
- A64-bit block size, 112-bit key length
- B64-bit block size, 168-bit key length
- C128-bit block size, 192-bit key length
- D128-bit block size, 256-bit key length
- E192-bit block size, 256-bit key length
How the community answered
(18 responses)- B6% (1)
- C89% (16)
- E6% (1)
Why each option
Advanced Encryption Standard (AES) supports a fixed block size of 128 bits and key lengths of 128, 192, or 256 bits.
AES mandates a 128-bit block size; 64-bit is incorrect for the block size.
AES mandates a 128-bit block size; 64-bit is incorrect for the block size.
AES uses a 128-bit block size and supports a 192-bit key length, making this a valid combination according to the NIST FIPS 197 standard.
AES uses a 128-bit block size and supports a 256-bit key length, making this a valid combination according to the NIST FIPS 197 standard.
AES mandates a 128-bit block size; 192-bit is incorrect for the block size.
Concept tested: AES block and key sizes
Source: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197.pdf
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