Hash value

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Definition

A fixed-length output of a one-way function; the same input always gives the same hash and it cannot be reversed. Used to check integrity and store passwords (with a salt).

Example: If the file changes, the hash changes.

Found in: syllabus, school notes.

Short version to memorise (key terms bank)

Fixed-length output of a one-way function.

Where you'll use it in the test

Syllabus area: Y12 Programming for the Web.

Question types it can appear in

Multiple choice: Pick the option that matches the definition or example.
Fill in the blanks: Choose this term to complete a statement or table.
Short answer: Define, outline or explain it and tie it to the scenario.

How to use it

A model sentence

General advice, built from the definition and example above

“A fixed-length output of a one-way function; the same input always gives the same hash and it cannot be reversed.” Then apply it: If the file changes, the hash changes.

In a short answer, give the definition in your own words first, then tie it to the situation in the question. Do not copy the example above unless it fits the scenario.

Command words used with it

General advice

No linked question shows the command word for this term. Across the past short answer questions in this bank the words used most are: Explain, Outline, Describe, Compare, Classify, Analyse. Check the actual word in your question.

Go deeper

Flashcard: Hash value in Programming for the Web (Year 12) · study that set
Memorise: Processes for securing the web
Key terms bank entry: Hash value
Notes: Explain the processes for securing the web, including Secure Sockets Layer (SSL)… (Programming for the Web (Year 12))
Notes: Cryptography and sandboxing in 'security by design' (Secure Software Architecture (Year 12))
Notes: Processes for securing the web (Programming for the Web (Year 12))
Full term page: every question, note and marking comment for Hash value

Check yourself

Explain “Hash value” in one sentence, give an example, and name a question type that could test it.

Reveal the answer

A fixed-length output of a one-way function; the same input always gives the same hash and it cannot be reversed. Used to check integrity and store passwords (with a salt).

Example: If the file changes, the hash changes.

Could be tested as: Multiple choice, Fill in the blanks, Short answer.

Quick multiple choice

Which property of a hash function is demonstrated if changing one letter in a document produces a completely different hash value?

The hash can be reversed to recover the document
Hashes can only be created for text
The hash value grows with the document size
Any change to the input changes the output, so tampering can be detected

Show the answer

Hashes have a fixed-length output and small input changes give very different outputs, which is why they check integrity.

Source: original (written for this study pack; not a NESA question). Open it in the multiple-choice bank.