Public-key cryptography concept: In a public key encryption system, who can successfully decode (decrypt) the transmitted data?

Introduction / Context:
Public-key cryptography uses a key pair: a public key that can be shared openly and a private key that must be kept secret. Understanding who can decrypt ciphertext under this model is fundamental to secure communications and authentication on networks.

Given Data / Assumptions:

• A sender encrypts data using the receiver’s public key.
• The receiver holds the corresponding private key securely.
• Only the matching private key can decrypt data encrypted by its paired public key.

Concept / Approach:

Asymmetric encryption ensures confidentiality: anyone can encrypt to a recipient using the recipient’s public key, but only the intended recipient can decrypt using their private key. This is distinct from digital signatures, where the sender uses a private key to sign and others use the public key to verify authenticity.

Step-by-Step Solution:

Verification / Alternative check:

Standard protocols (e.g., hybrid schemes in TLS) rely on public-key operations for key exchange and confidentiality—only holders of the private key can complete decryption.

Why Other Options Are Wrong:

• allows anyone to decode: False; that would defeat confidentiality.
• allows only the correct sender to decode: Decryption is for the receiver, not the sender.
• does not encode the data: Contradicts the premise of an encryption system.
• None of the above: Incorrect because the correct receiver is the right choice.

Common Pitfalls:

Confusing encryption (public key) with signatures (private key); assuming key pairs are interchangeable without directionality; ignoring key management and authenticity of public keys.

Final Answer:

allows only the correct receiver to decode the data