computer science

Secure Hypertext Transfer Protocol

Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol rather than just read about it. In short: Secure Hypertext Transfer Protocol (S-HTTP) is an obsolete alternative to the HTTPS protocol for encrypting web communications carried over the Internet. It was developed by Eric Rescorla and Allan M.

Key takeaways

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

Reference excerpt

Secure Hypertext Transfer Protocol (S-HTTP) is an obsolete alternative to the HTTPS protocol for encrypting web communications carried over the Internet. It was developed by Eric Rescorla and Allan M. Schiffman at Enterprise Integration Technologies in 1994 and published in 1999 as RFC 2660. Netscape's dominance of the browser market led to HTTPS becoming the de facto method for securing web communications.

Comparison to HTTP over TLS (HTTPS) S-HTTP encrypts only the served page data and submitted data like POST fields, leaving the initiation of the protocol unchanged. Because of this, S-HTTP could be used concurrently with HTTP (unsecured) on the same port, as the unencrypted header would determine whether the rest of the transmission is encrypted. In contrast, HTTP over TLS wraps the entire communication within Transport Layer Security (TLS; formerly SSL), so the encryption starts before any protocol data is sent. This creates a name-based virtual hosting "chicken and egg" issue with determining which DNS name was intended for the request. This means that HTTPS implementations without Server Name Indication (SNI) support require a separate IP address per DNS name, and all HTTPS implementations require a separate port (usually 443 vs. HTTP's standard 80) for unambiguous use of encryption (treated in most browsers as a separate URI scheme, https://). As documented in RFC 2817, HTTP can also be secured by implementing HTTP/1.1 Upgrade headers and upgrading to TLS. Running HTTP over TLS negotiated in this way does not have the implications of HTTPS with regards to name-based virtual hosting (no extra IP addresses, ports, or URI space). However, few implementations support this method. In S-HTTP, the desired URL is not transmitted in the cleartext headers, but left blank; another set of headers is present inside the encrypted payload. In HTTP over TLS, all headers are inside the encrypted payload and the server application does not generally have the opportunity to gracefully recover from TLS fatal errors (including 'client certificate is untrusted' and 'client certificate is expired').

References

External links RFC 2660 The Secure HyperText Transfer Protocol

Illustrations

Worked examples

Example 1 — a first encounter with Secure Hypertext Transfer Protocol

Start with the simplest possible case. Write down what Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol

In research: Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol 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: Secure Hypertext Transfer Protocol is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cryptographic protocols, Hypertext Transfer Protocol, so understanding it makes those chapters shorter.
In everyday life: Look for Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol in 20 minutes

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

Frequently asked questions

What is Secure Hypertext Transfer Protocol in simple terms?

Why does Secure Hypertext Transfer Protocol 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 Secure Hypertext Transfer Protocol?

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 Secure Hypertext Transfer Protocol.