computer science

JSON Web Signature

JSON Web Signature is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand JSON Web Signature rather than just read about it. In short: A JSON Web Signature (abbreviated JWS) is an IETF-proposed standard (RFC 7515) for signing arbitrary data. This is used as the basis for a variety of web-based technologies including JSON Web Token.

Key takeaways

JSON Web Signature belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect JSON Web Signature to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of JSON Web Signature from memory before moving on to harder problems.

Reference excerpt

A JSON Web Signature (abbreviated JWS) is an IETF-proposed standard (RFC 7515) for signing arbitrary data. This is used as the basis for a variety of web-based technologies including JSON Web Token.

Purpose JWS is a way to ensure integrity of information in a highly serializable, machine-readable format. That means that it is information, along with proof that the information hasn't changed since being signed. It can be used for sending information from one web site to another, and is especially aimed at communications on the web. It even contains a compact form optimized for applications like URI query parameters.

Examples

Web commerce JWS can be used for applications in which digitally signed information must be sent in a machine-readable format, such as e-commerce. For example, say a user named Bob is browsing widget prices on a web site (widgets.com), and wishes to get a quote on one of them. Then widgets.com could provide Bob with a JWS object containing all relevant information about the widget, including the price, then sign it using their private key. Then Bob would have a non-repudiable price quote for the product.

Access to third-party resources Maybe Widgets.com and WidgetStorage.com have a deal in which WidgetStorage.com will accept coupons from Widgets.com in exchange for traffic. Widgets.com could issue JWS giving Bob a 10% discount on the WidgetStorage.com site. Again, because the data is signed, WidgetStorage can know that Widgets.com emitted this. If the data was not signed, then Bob could change his discount to 50% and no one would know just from looking at the data.

Limitations JWS is one of the standards in the JOSE series and is meant to be used in combination with them. For example, for encryption JSON Web Encryption (JWE) is supposed to be used in conjunction. As of 2015, JWS was a proposed standard, and was part of several other IETF proposed standards, and there was code available on the web to implement the proposed standard.

References

Worked examples

Example 1 — a first encounter with JSON Web Signature

Start with the simplest possible case. Write down what JSON Web Signature claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to JSON Web Signature before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about JSON Web Signature ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of JSON Web Signature

In research: JSON Web Signature appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses JSON Web Signature in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: JSON Web Signature is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer access control, Internet Standards, JSON, so understanding it makes those chapters shorter.
In everyday life: Look for JSON Web Signature outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study JSON Web Signature in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what JSON Web Signature means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain JSON Web Signature out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is JSON Web Signature in simple terms?

A JSON Web Signature (abbreviated JWS) is an IETF-proposed standard (RFC 7515) for signing arbitrary data. This is used as the basis for a variety of web-based technologies including JSON Web Token.

Why does JSON Web Signature matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study JSON Web Signature?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on JSON Web Signature.