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SY0-501 · Question #243

Which of the following cryptographic algorithms is irreversible?

The correct answer is B. SHA-256. SHA-256 is an irreversible cryptographic hash function that produces a fixed-size output, designed so that the original input cannot be reconstructed from the hash value.

Submitted by lucia.co· Mar 4, 2026General security concepts

Question

Which of the following cryptographic algorithms is irreversible?

Options

  • ARC4
  • BSHA-256
  • CDES
  • DAES

How the community answered

(58 responses)
  • A
    3% (2)
  • B
    78% (45)
  • C
    7% (4)
  • D
    12% (7)

Why each option

SHA-256 is an irreversible cryptographic hash function that produces a fixed-size output, designed so that the original input cannot be reconstructed from the hash value.

ARC4

RC4 is a symmetric stream cipher used for encryption, which is by definition designed to be reversible to decrypt the original plaintext from the ciphertext using the correct key.

BSHA-256Correct

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function, which takes an input and produces a fixed-size alphanumeric string called a hash value. This process is inherently one-way, meaning it is computationally infeasible to reverse the hash value back to the original input data.

CDES

DES (Data Encryption Standard) is a symmetric block cipher used for encryption, meaning it is designed to be reversible to decrypt the original plaintext from the ciphertext using the correct key.

DAES

AES (Advanced Encryption Standard) is a symmetric block cipher used for encryption, meaning it is designed to be reversible to decrypt the original plaintext from the ciphertext using the correct key.

Concept tested: Cryptographic hash functions vs. encryption algorithms

Source: https://learn.microsoft.com/en-us/windows/win32/seccrypto/cryptographic-hash-functions

Topics

#hashing#SHA-256#one-way function#cryptographic algorithms

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