mathematics

Identicon

Identicon is a mathematics 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 Identicon rather than just read about it. In short: An Identicon is a visual representation of a hash value, usually of an IP address, that serves to identify a user of a computer system as an effectively random form of avatar while protecting the user's privacy. The original Identicon was a 9-block graphic, and the representation has been extended to other graphic forms by third parties.

Key takeaways

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

Reference excerpt

An Identicon is a visual representation of a hash value, usually of an IP address, that serves to identify a user of a computer system as an effectively random form of avatar while protecting the user's privacy. The original Identicon was a 9-block graphic, and the representation has been extended to other graphic forms by third parties.

Invention Don Park came up with the Identicon idea on January 18, 2007. In his words:

I originally came up with this idea to be used as an easy means of visually distinguishing multiple units of information, anything that can be reduced to bits. It's not just IPs but also people, places, and things. IMHO, too much of the web what we read are textual or numeric information which are not easy to distinguish at a glance when they are jumbled up together. So I think adding visual identifiers will make the user experience much more enjoyable. A similar method had previously been described by Adrian Perrig and Dawn Song in their 1999 publication on hash visualization, which had already seen wide use such as in the random art of SSH keys.

Applications GitHub and Roll20 both use identicons to visually differentiate users who have not set their own avatar. Wikis and blogs may generate identicons to visually identify authors based on IP addresses. This provides some protection against impersonation without requiring authentication. Third-party software is available to generate identicons for the purposes of identifying eBay sellers. The original Identicon idea has been expanded to include a couple of new, simple yet very effective, anti-phishing protection schemes. One of them requires client-side support; Park is interested in talking to browser vendors regarding its incorporation. He calls this expansion "Gemini."

References

External links Don Park's original source code at GitHub Mavenized project based on Don Park's original source code at GitHub Identicons as Visual Fingerprints by Phil Haack PHP-Identicons Identicon CFC - ColdFusion implementation of Identicons NIdenticon - .Net implementation of Identicons Awesome Identicon - A curated list of identicon examples

Illustrations

Worked examples

Example 1 — a first encounter with Identicon

Start with the simplest possible case. Write down what Identicon claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 Identicon 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 Identicon 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 Identicon

In research: Identicon appears in mathematics 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 Identicon 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: Identicon is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer icons, Hash functions, Identifiers, so understanding it makes those chapters shorter.
In everyday life: Look for Identicon 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 Identicon in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Identicon 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 Identicon out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Identicon in simple terms?

Why does Identicon matter?

Because it connects several mathematics 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 Identicon?

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 Identicon.