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computer science

Password cracking

Password cracking 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 Password cracking rather than just read about it. In short: In cryptanalysis and computer security, password cracking is the process of guessing passwords protecting a computer system. A common approach (brute-force attack) is to repeatedly try guesses for the password and to check them against an available cryptographic hash of the password.

Key takeaways

  • Password cracking 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 Password cracking to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Password cracking from memory before moving on to harder problems.

Reference excerpt

In cryptanalysis and computer security, password cracking is the process of guessing passwords protecting a computer system. A common approach (brute-force attack) is to repeatedly try guesses for the password and to check them against an available cryptographic hash of the password. Another type of approach is password spraying, which is often automated and occurs slowly over time to remain undetected, using a list of common passwords. The purpose of password cracking might be to help a user recover a forgotten password (since installing an entirely new password would involve System Administration privileges), to gain unauthorized access to a system, or to act as a preventive measure whereby system administrators check for easily crackable passwords. On a file-by-file basis, password cracking is utilized to gain access to digital evidence to which a judge has allowed access when a particular file's permissions are restricted. Brute-force password guessing attacks against online systems are usually ineffective because systems are designed to lock accounts after a certain number of unsuccessful login attempts. Obtaining the cryptographic hash of the password makes it possible to perform an unlimited number of offline guesses. Hash files might be obtained by third parties by court-ordered access, or as part of an illegal data breach. If passwords are reused across websites, the hash file obtained from one website can be used for cracking, and then the discovered passwords can be attempted against the same email addresses on other websites. The password spraying approach evades account lockout countermeasures by guessing the same password across many accounts, allowing time to pass between attempts on the same account, which might include legitimate logins. This approach does not target specific accounts.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Password cracking

Start with the simplest possible case. Write down what Password cracking 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 Password cracking 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 Password cracking 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 Password cracking

In research
Password cracking 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 Password cracking 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
Password cracking is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cryptographic attacks, Password cracking software, System administration, so understanding it makes those chapters shorter.
In everyday life
Look for Password cracking 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 Password cracking in 20 minutes

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

Frequently asked questions

What is Password cracking in simple terms?

In cryptanalysis and computer security, password cracking is the process of guessing passwords protecting a computer system. A common approach (brute-force attack) is to repeatedly try guesses for the password and to check them against an available cryptographic hash of the password.

Why does Password cracking 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 Password cracking?

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 Password cracking.

Tags

  • Cryptographic attacks
  • Password cracking software
  • System administration

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