computer science

GPG Mail

GPG Mail 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 GPG Mail rather than just read about it. In short: GPG Mail is a commercial extension for Apple Mail which comes as part of GPG Suite, a software collection that provides easy access to a collection of tools designed to secure your communications and encrypt files. GPG Mail provides public key email encryption and signing.

Key takeaways

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

Reference excerpt

GPG Mail is a commercial extension for Apple Mail which comes as part of GPG Suite, a software collection that provides easy access to a collection of tools designed to secure your communications and encrypt files. GPG Mail provides public key email encryption and signing. It integrates with the default email client Apple Mail under macOS and the actual cryptographic functionality is handled by GNU Privacy Guard.

History GPG Mail was first released on February 7, 2001, by Stéphane Corthésy. Since 2010 GPG Mail is maintained by GPGTools. While GNU Privacy Guard is free open-source software, use of GPG Mail requires purchase of a support plan. On September 21, 2018, the developer introduced GPG Mail 3.0 as a part of GPG Suite 2018.4, a new software release that included support for macOS Mojave. In this release, the developer removed the free license option for GPG Mail. A lot of users that relied on automated upgrades were caught by surprise, which prompted a significant backlash from the community. While the licensing change was identified in the release notes for GPG Suite 2018.4, many believed that such a big change required more prominent notifications to avoid the perception of "bait and switch". In August 2019 the default key server was switched to hagrid, a new verifying key server located at keys.openpgp.org. This improved the quality of search results for public keys and increased control for users over their public keys stored on the server. On November 24, 2020, GPG Mail 5 was introduced, supporting macOS Mojave, macOS Catalina and macOS Big Sur. On September 16, 2024, a beta version with support for macOS Sequoia was released.

See also Email encryption OpenPGP End-to-end encryption Cryptography

References

External links GPGTools website

Worked examples

Example 1 — a first encounter with GPG Mail

Start with the simplest possible case. Write down what GPG Mail 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 GPG Mail 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 GPG Mail 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 GPG Mail

In research: GPG Mail 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 GPG Mail 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: GPG Mail is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cryptographic software, MacOS security software, OpenPGP, so understanding it makes those chapters shorter.
In everyday life: Look for GPG Mail 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 GPG Mail in 20 minutes

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

Frequently asked questions

What is GPG Mail in simple terms?

Why does GPG Mail 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 GPG Mail?

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 GPG Mail.