Which Encryption Method Uses a Single Shared Key?
A systems administrator uses a key to encrypt a message being sent to a peer in a different branch office. The peer then uses the same key to decrypt the message. Which of the following describes this example?
Community Votes
85% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
It tests your ability to distinguish single-key cryptographic protocols from multi-key or non-reversible functions, with the main trap being the assumption that geographic separation requires asymmetric cryptography.
This question evaluates foundational knowledge of cryptographic key management models. Community consensus confirms that utilizing one identical key for both encoding and decoding data definitively characterizes symmetric encryption.
Candidates often incorrectly select Asymmetric or Hashing, typically misreading 'different branch office' as a trigger for public/private key usage, or confusing reversible encryption with one-way data digests.
Community Discussion (7 comments)
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Expert Analysis
Core Concept
Cryptographic algorithms are fundamentally categorized by how they handle access keys. The scenario explicitly states that a single key is utilized for both the encryption and decryption processes. This direct relationship is the cornerstone of secure communication architectures.Why Option A is Correct
Symmetric encryption relies on a shared secret key known exclusively to the communicating endpoints. Because both the sender and receiver use the exact same key to lock and unlock the payload, the scenario aligns perfectly with this model. Community feedback strongly validates this, with multiple users noting that "the same key for both processes" immediately isolates symmetric cryptography [1][2][7].Why Other Options Are Incorrect
- Asymmetric encryption (Option B) employs a mathematically linked key pair: a public key for encryption and a private key for decryption. Since the prompt specifies the identical key handles both actions, this option is structurally impossible.
- Hashing (Option C) is a one-way mathematical algorithm used to generate fixed-length digests for integrity verification. It lacks keys entirely and cannot reverse-engineer the original message. Although one candidate initially voted C, their explanatory comment actually defined symmetric encryption, illustrating a common test-day labeling error [6].
- Salting (Option D) involves appending random data to passwords prior to hashing to mitigate rainbow table attacks. It serves as a security enhancement for storage, not a transmission encryption method.
Official Reference
Exam Strategy
When analyzing cryptography questions, immediately scan for keywords indicating key distribution models: look for "shared," "same," or "secret" versus "public," "private," or "pair." If a single key manages both locking and unlocking, instantly eliminate asymmetric and hashing options to conserve time and prevent overcomplication.
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