You have been asked to encrypt a large file using a secure encryption algorithm so you can send it via e-mail to your supervisor. Encryption speed is important. The key will not be transmitted…

Dervla O.Apr 21, 2026

Symmetric encryption is the right call here. The stem gives you two signals pointing away from asymmetric: large file size and no key transmission across a network, which removes the one problem asymmetric solves, so you eliminate A immediately. Hash is a one-way function, not encryption, so C is gone. PGP actually uses a combination of both under the hood, which makes it a distractor when the question isolates the underlying algorithm type. Symmetric handles bulk data fast and the key-sharing concern is moot since the key stays local.

Ingrid P.Apr 16, 2026

Symmetric wins here, fast bulk encryption and no key exchange needed.

Hiroshi T.Apr 29, 2026

I almost went with B thinking PGP covers this, but PGP itself uses symmetric encryption for the actual file payload, and since the key stays local, D is the direct answer.

Mei-Ling H.May 7, 2026

The question gives two clues you have to catch together: "large file" and "key will not be transmitted." The word "large" alone points you away from asymmetric, because asymmetric algorithms like RSA are computationally expensive and impractical for bulk data. Symmetric encryption uses the same key to encrypt and decrypt, which is much faster, and the concern that always comes up against it, which is securely sharing that key, is already eliminated by the condition that the key stays local. Hash is a one-way function and cannot be decrypted at all, so C is out immediately once you read "encrypt." My clarifying question is this: if the question had said the key DOES need to be transmitted to the supervisor, would the correct answer change to asymmetric, or would it still be symmetric but with asymmetric used just to protect the key in transit, like how PGP actually works? I want to make sure I understand where the line is between the two scenarios on this exam.

Grace U.May 4, 2026

I still remember sitting at the testing center sweating over this one, because asymmetric sounds fancy and secure, but then I remembered that symmetric encryption uses the same key for both sides, which makes it dramatically faster for bulk data, and since the question says the key is NOT crossing a network the whole "key exchange problem" just disappears. Locked in D and moved on, and when the results came back I was glad I trusted the logic instead of the hype around public-key stuff.