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SY0-301 · Question #737

Which of the following are restricted to 64-bit block sizes? (Select TWO).

The correct answer is B. DES E. 3DES. DES and 3DES are symmetric block ciphers that both operate on 64-bit block sizes, distinguishing them from AES which uses a 128-bit block size.

General security concepts

Question

Which of the following are restricted to 64-bit block sizes? (Select TWO).

Options

  • APGP
  • BDES
  • CAES256
  • DRSA
  • E3DES
  • FAES

How the community answered

(54 responses)
  • B
    87% (47)
  • C
    7% (4)
  • D
    4% (2)
  • F
    2% (1)

Why each option

DES and 3DES are symmetric block ciphers that both operate on 64-bit block sizes, distinguishing them from AES which uses a 128-bit block size.

APGP

PGP (Pretty Good Privacy) is an encryption program and standard, not a block cipher with a defined block size.

BDESCorrect

DES (Data Encryption Standard) encrypts data in 64-bit blocks using a 56-bit key, making it one of the original 64-bit block ciphers.

CAES256

AES256 refers to AES with a 256-bit key; AES uses a 128-bit block size regardless of key length.

DRSA

RSA is an asymmetric (public-key) algorithm that does not use fixed block sizes in the same way as symmetric block ciphers.

E3DESCorrect

3DES (Triple DES) applies DES encryption three times to each 64-bit block, inheriting the 64-bit block size from DES while improving key strength.

FAES

AES (Advanced Encryption Standard) uses a 128-bit block size for all key lengths (128, 192, or 256 bits).

Concept tested: DES and 3DES 64-bit block size characteristic

Source: https://csrc.nist.gov/publications/detail/fips/46/3/archive/1999-10-25

Topics

#symmetric encryption#block cipher#DES#3DES

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