Separate a Hash from Encryption
Distinguish digest comparison, reversible confidentiality protection and source authentication.
About 22 minutes, plus any extended practice
Supplied materials
- Paper and pencil; answers may also be spoken or typed.
- All cases, labels, numbers and rules are supplied on this page. No real account, private information or purchase is needed.
Learn the idea
A cryptographic hash maps input data to a digest. It is not reversible encryption and does not by itself prove who created the input. Comparing a digest with a trusted expected digest can support integrity checking under its assumptions. Use vetted cryptographic tools rather than an invented classroom substitution as real protection.
Distinguish digest comparison, reversible confidentiality protection and source authentication. Matching an untrusted digest supplied by an attacker does not establish trusted origin.
Use this supplied case: Data is mapped to a fixed-length digest. Which mechanism or evidence is stated? The task is to connect the given information to the computing idea. Write a short evidence trail so another learner can reproduce your choice. The simplified case describes the stated model, not every real system.
- Represent the supplied worked case with a labeled drawing, table or short trace.
- Distinguish digest comparison, reversible confidentiality protection and source authentication.
- Explain why the worked answer fits and why one alternative does not.
- Try the new check and practice cases; revisit the stated rule if your evidence does not match.
See the method in action
Data is mapped to a fixed-length digest. Which mechanism or evidence is stated? The supported answer is Hash digest. Distinguish digest comparison, reversible confidentiality protection and source authentication. Matching an untrusted digest supplied by an attacker does not establish trusted origin. A cryptographic hash maps input data to a digest.
Check your reasoning
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Helpful tips
- Distinguish digest comparison, reversible confidentiality protection and source authentication.
- Matching an untrusted digest supplied by an attacker does not establish trusted origin.
See the answer and explanation
Encryption with decryption key
The supplied case states: Recipient uses a key to decrypt ciphertext. Which mechanism or evidence is stated? Under the stated distinction, this identifies Encryption with decryption key. A cryptographic hash maps input data to a digest. It is not reversible encryption and does not by itself prove who created the input. Comparing a digest with a trusted expected digest can support integrity checking under its assumptions. Use vetted cryptographic tools rather than an invented classroom substitution as real protection. Distinguish digest comparison, reversible confidentiality protection and source authentication.
Take it further
A file and claimed matching digest come from the same unknown sender. Expected: comparison does not establish trusted origin; obtain the expected evidence through a trusted context.
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More practice: try new cases
Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.
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Check the subject sources
These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.