computer science

Simple Authentication and Security Layer

Simple Authentication and Security Layer 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 Simple Authentication and Security Layer rather than just read about it. In short: Simple Authentication and Security Layer (SASL) is a framework for authentication and data security in Internet protocols. It decouples authentication mechanisms from application protocols, in theory allowing any authentication mechanism supported by SASL to be used in any application protocol that uses SASL.

Key takeaways

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

Reference excerpt

Simple Authentication and Security Layer (SASL) is a framework for authentication and data security in Internet protocols. It decouples authentication mechanisms from application protocols, in theory allowing any authentication mechanism supported by SASL to be used in any application protocol that uses SASL. Authentication mechanisms can also support proxy authorization, a facility allowing one user to assume the identity of another. They can also provide a data security layer offering data integrity and data confidentiality services. DIGEST-MD5 provides an example of mechanisms which can provide a data-security layer. Application protocols that support SASL typically also support Transport Layer Security (TLS) to complement the services offered by SASL. John Gardiner Myers wrote the original SASL specification (RFC 2222) in 1997. In 2006, that document was replaced by RFC 4422 authored by Alexey Melnikov and Kurt D. Zeilenga. SASL, as defined by RFC 4422 is an IETF Standard Track protocol and is, as of 2006, a Proposed Standard.

SASL mechanisms A SASL mechanism implements a series of challenges and responses. Defined SASL mechanisms include:

EXTERNAL where authentication is implicit in the context (e.g., for protocols already using IPsec or TLS) ANONYMOUS for unauthenticated guest access PLAIN a simple cleartext password mechanism, defined in RFC 4616 OTP a one-time password mechanism. Obsoletes the SKEY mechanism. SKEY an S/KEY mechanism. CRAM-MD5 a simple challenge-response scheme based on HMAC-MD5. DIGEST-MD5 (historic), partially HTTP Digest compatible challenge-response scheme based upon MD5. DIGEST-MD5 offered a data security layer. SCRAM (RFC 5802), modern challenge-response scheme based mechanism with channel binding support NTLM an NT LAN Manager authentication mechanism GS2- family of mechanisms supports arbitrary GSS-API mechanisms in SASL. It is now standardized as RFC 5801. GSSAPI for Kerberos V5 authentication via the GSSAPI. GSSAPI offers a data-security layer. BROWSERID-AES128 for Mozilla Persona authentication EAP-AES128 for GSS EAP authentication MSN Chat GateKeeper (& GateKeeperPassport) a challenge-response mechanism developed by Microsoft for MSN Chat OAUTHBEARER OAuth 2.0 bearer tokens (RFC 6750), communicated through TLS OAUTH10A OAuth 1.0a message-authentication-code tokens (RFC 5849, Section 3.4.2)

SASL-aware application protocols Application protocols define their representation of SASL exchanges with a profile. A protocol has a service name such as "ldap" in a registry shared with GSSAPI and Kerberos. As of 2012 protocols currently supporting SASL include:

Application Configuration Access Protocol (ACAP) Advanced Message Queuing Protocol (AMQP) Blocks Extensible Exchange Protocol (BEEP) Internet Message Access Protocol (IMAP) Internet Message Support Protocol (IMSP) Internet Relay Chat (IRC) (with IRCX or the IRCv3 SASL extension) Lightweight Directory Access Protocol (LDAP) libvirt ManageSieve (RFC 5804) memcached Post Office Protocol (POP) Remote Framebuffer (RFB) protocol used by VNC Simple Mail Transfer Protocol (SMTP) Subversion svn protocol Extensible Messaging and Presence Protocol (XMPP)

Worked examples

Example 1 — a first encounter with Simple Authentication and Security Layer

Start with the simplest possible case. Write down what Simple Authentication and Security Layer 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 Simple Authentication and Security Layer 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 Simple Authentication and Security Layer 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 Simple Authentication and Security Layer

In research: Simple Authentication and Security Layer 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 Simple Authentication and Security Layer 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: Simple Authentication and Security Layer is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer access control protocols, Cryptographic protocols, Internet Standards, so understanding it makes those chapters shorter.
In everyday life: Look for Simple Authentication and Security Layer 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 Simple Authentication and Security Layer in 20 minutes

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

Frequently asked questions

What is Simple Authentication and Security Layer in simple terms?

Why does Simple Authentication and Security Layer 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 Simple Authentication and Security Layer?

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 Simple Authentication and Security Layer.