computer science

Nettle (cryptographic library)

Nettle (cryptographic library) 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 Nettle (cryptographic library) rather than just read about it. In short: Nettle is a cryptographic library designed to fit easily in a wide range of toolkits and applications. It began as a collection of low-level cryptography functions from lsh in 2001.

Key takeaways

Nettle (cryptographic library) 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 Nettle (cryptographic library) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nettle (cryptographic library) from memory before moving on to harder problems.

Reference excerpt

Nettle is a cryptographic library designed to fit easily in a wide range of toolkits and applications. It began as a collection of low-level cryptography functions from lsh in 2001. Since June 2009 (version 2.0) Nettle is a GNU package.

Features Since version 3, nettle provides

the AES block cipher - a subset of Rijndael, with assembly optimizations for x86 and sparc the ARCFOUR, also known as RC4 stream cipher, with x86 and sparc assembly the ARCTWO, also known as RC2, stream cipher BLOWFISH, CAMELLIA, with x86 and x86_64 assembly optimizations CAST-128 DES and 3DES block ciphers the ChaCha stream cipher, with assembly for x86_64 GOSTHASH94 the MD2, MD4 and MD5 with x86 assembly digests the PBKDF2 key derivation function the POLY1305 with assembly for x86_64 and UMAC message authentication codes RIPEMD160 the Salsa20 stream cipher with assembly for x86_64 and ARM the SERPENT block cipher with assembly for x86_64 SHA-1 with x86, x86_64 and ARM assembly the SHA-2 (SHA-224, SHA-256, SHA-384, and SHA-512) digests SHA-3 a subset of the Keccak digest family the TWOFISH block cipher RSA DSA and ECDSA public-key algorithms the Yarrow pRNG Version 3.1 introduced support for Curve25519 and EdDSA operations. The public-key algorithms use GMP. Nettle is used by

GnuTLS AIDE since v0.19

License and motivation An API which fits one application well may not work well in a different context resulting in a proliferation of cryptographic libraries designed for particular applications. Nettle is an attempt to avoid this problem by doing one thing (the low-level cryptography) and providing a simple and general interface to it. In particular, Nettle doesn't do algorithm selection, memory allocation or any I/O. Thus Nettle is intended to provide a core cryptography library upon which numerous application and context specific interfaces can be built. The code, test cases, benchmarks, documentation, etc. of these interfaces can then be shared without having to replicate Nettle's cryptographic code. Nettle is primarily licensed under a dual licence scheme comprising The GNU General Public License version 2 or later and The GNU Lesser General Public License version 3 or later. A few individual files are licensed under more permissive licences or in the public domain. The copyright notices at the top of the library's source files precisely define the licence status of particular files. The Nettle manual "is in the public domain" and may be used and reproduced freely.

Worked examples

Example 1 — a first encounter with Nettle (cryptographic library)

Start with the simplest possible case. Write down what Nettle (cryptographic library) 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 Nettle (cryptographic library) 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 Nettle (cryptographic library) 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 Nettle (cryptographic library)

In research: Nettle (cryptographic library) 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 Nettle (cryptographic library) 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: Nettle (cryptographic library) is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2020 software, Cryptographic software, Free computer libraries, so understanding it makes those chapters shorter.
In everyday life: Look for Nettle (cryptographic library) 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 Nettle (cryptographic library) in 20 minutes

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

Frequently asked questions

What is Nettle (cryptographic library) in simple terms?

Nettle is a cryptographic library designed to fit easily in a wide range of toolkits and applications. It began as a collection of low-level cryptography functions from lsh in 2001.

Why does Nettle (cryptographic library) 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 Nettle (cryptographic library)?

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 Nettle (cryptographic library).