Which of the following statements are true about Public-key cryptography? Each correct answer represents a complete solution. Choose two.

Question

Options

• AData encrypted with the secret key can only be decrypted by another secret key.
• BThe secret key can encrypt a message, and anyone with the public key can decrypt it.
• CThe distinguishing technique used in public key-private key cryptography is the use of
• DData encrypted by the public key can only be decrypted by the secret key.

• A
  7% (4)
• B
  77% (44)
• C
  16% (9)

Explanation

B and D together describe the two fundamental operations of asymmetric cryptography. In public-key cryptography, the key pair works in both directions: a message encrypted with the public key can only be decrypted by the corresponding private (secret) key (D) - this ensures confidentiality. Conversely, a message encrypted with the private key can be decrypted by anyone holding the public key (B) - this is the basis of digital signatures, proving the sender's identity.

A is wrong because data encrypted with the secret key is decrypted by the public key, not by "another secret key" - that would describe symmetric cryptography.

C is wrong because the statement is simply incomplete; it cuts off mid-sentence and presents no meaningful claim.

Memory tip: Think of a padlock analogy - the public key locks (encrypts), and only the private key unlocks (decrypts). Flip it around for signatures: the private key "signs" and the public key "verifies." If a choice describes secret-to-secret operations, it's describing symmetric crypto - eliminate it.

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