What is a symmetric key?

Question

Options

• AA key used for encryption and decryption that is the same
• BA key used for encryption that is different from the key used for decryption
• CA key used for decryption that is different from the key used for encryption
• DA key used for both encryption and decryption that is generated randomly

• A
  89% (59)
• B
  3% (2)
• C
  2% (1)
• D
  6% (4)

Explanation

Option A is correct because a symmetric key is defined by the use of a single shared key for both encrypting and decrypting data - the same key performs both operations, which is the core property that makes it "symmetric."

Why the distractors are wrong:

• B and C describe asymmetric (public-key) cryptography, where two different keys are used - a public key encrypts and a private key decrypts (or vice versa).
• D is a trick: while symmetric keys can be randomly generated, random generation is not what defines them. The defining characteristic is key sameness, not key generation method - asymmetric keys are also randomly generated.

Memory tip: Think of "symmetric" like a mirror - both sides are identical. One key, same on both ends, for both directions.

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