Add-ons An extension for Firefox that gives it additional features, functionality, uses, etc.  Available from

algorithm A precisely specified method for performing a particular process, one that can readily be turned into a computer program in almost any programming language. From algorism, method of calculation, from mathematician Muhammad ibn-Musa al-Khowarizmi.

authentication Any process for assuring each of two communicating parties of the other's identity, or for guaranteeing that a set of data has not been changed.

Awesome Bar Alternate name for the Firefox Location Bar, so called because of its remarkable power to suggest pages the user might want to return to from just a few characters of the URL.

backdoor An entry point into a program or computer that the user is not told about. These may be built into legitimate software for support and maintenance purposes, although such designs are not acceptable when users know about them. More commonly, backdoors are installed by malware.

bot A computer that has been taken over by malware (software created with bad intentions) for an external user.

botnet A network of bots or zombie computers.

certificate A digitally signed document from a trusted authority stating the identity of the holder.

client A computer running a Web browser such as Firefox, or some other end-user software, in communication with a server running Apache or some other software to provide data or services.

command line The text terminal user interface in which the user types commands, as opposed to the GUI interface where users click icons or select commands from menus.

computational infeasability The level of difficulty of a problem that cannot be solved on current computers or any that we can currently imagine in their usable lifetime, or sometimes even in a period longer than the present age of the Universe. A property of mathematical problems used as the basis of cryptographic systems.

cookie A short text string stored on the client computer to identify it or its user to the server, or to hold data temporarily during a transaction.

cryptography The field devoted to securing secrets, applying secure signatures to documents, and authenticating strangers to each other using mathematical transformations of their data.

cryptosystem A combination of cryptographic algorithms and protocols designed to accomplish some form of security, authentication, or both for a particular purpose.

digital signature An encrypted data object, or encrypted hash of a data object, created with the sender's private key. Anyone can use the sender's public key to recover the data or the hash, and thus verify that it came from that sender.

distribution A version of Linux distributed by an individual or organization.

distro Short for distribution.

DMCA Digital Millennium Copyright Act, a US-based legislation adopted in 1998 to extend and amend copyright laws. It is controversial because it forbids public discussion of the weaknesses of any cryptographic system used to prevent or restrict copying of copyrighted materials.

DRM Digital Rights Management, the use of encryption to protect copyrighted material from unauthorized copying.

Extension (See Add-on)

firewall Software to protect a computer from unwanted access.

FLOSS Free/Libre Open Source software licensed to guarantee users the essential software freedoms, including access to source code and the right to modify the code and distribute the new version under the same kind of license.

GUI Graphical User Interface with windows, icons, menus, and mouse control.

hack (positive) noun A brilliant bit of programming, particularly one previously thought impossible, or never thought of at all. (negative) verb Break into computers.

hacker (positive) A truly talented programmer who can make hardware do things that nobody expected. (negative) A person who breaks into computers for malicious purposes, or just to show he or she can do it.

hash A short signature calculated from a data object or file. Hashing algorithms are designed to make it computationally infeasible to create a different set of data with the same hash. To the extent that they succeed, checking the hash value for the data indicates that it has not been changed by errors in transmission or malicious interference.

HTML Hypertext Markup Language, the method of specifying format and other properties of a Web page.

HTTP Hypertext Transfer Protocol, the method a browser uses to communicate with a Web server.

HTTPS Hypertext Transfer Protocol Secure, a method for communication but with a Secure Security Layer or Transport Security Layer.

info A text-based Unix documentation-display program.

Java A highly portable computer language, created by Sun Microsystems, which is working toward putting all of it under a FLOSS license.

Javascript Originally ECMAscript, a programming language that can be embedded in Web pages. No relation to Java.

key exchange A secure protocol for setting up a secure session, starting from a situation in which the parties have no shared key. Each side creates a key, then one initiates a dialogue consisting of a sequence of numbers, computed so that the holder of each key can determine the other key, but an eavesdropper with neither key cannot determine either one.

license  A legal statement of rights and duties binding on the user or purchaser of software. Free licenses guarantee the rights of Software Freedom to the user, and require that those rights be passed on in any further distribution of the software or other software derived from it.

malware A general term combining the words malicious and software that describes software designed or used with intent to harm or cause disruption.

man page Terse text documentation for Unix command-line programs.

one-time password A password generated by a hardware token, and simultaneously on a server using the same algorithm.

personas Easy to use (and change) themes that allow you to personalize the look of your Firefox.

phishing A criminally fraudulent process of acquiring sensitive information via email or web site claiming to be legitimate seeking identifiable information.

port scan An attempt to take over a computer by testing each of its active communication ports.

public-key cryptography Any cryptographic system using two keys per user, one private and one public. The two keys must be inverses, that is, either one can be used to encrypt a message, and the other to decrypt it. It must be

rootkit A form of malware that takes over the target computer's operating system, and hides itself from the user and from system monitors and normal malware scanners.

RSA Rivest-Shamir-Adleman public-key cryptographic system.

RSS Really Simple Syndication is a method for publishing data feeds and subscribing to them in a Web browser, so that the latest updates automatically appear on a menu.

Security through Obscurity The attempt to protect encrypted data by keeping the encryption method secret.

script kiddy A derogatory term used to describe an inexperienced, often juvenille user of malware who cannot write his own, but just takes scripts or programs from others.

search engine A web-based program that allows users to search for and retrieve specific information from the World Wide Web.

server A computer offering services to clients.

SHA Secure Hash Algorithm, a widely used set of cryptographic hash algorithms. SHA-1 has been shown to have some limited weaknesses, which may also apply to SHA-2. These weaknesses cannot currently be exploited to break security where SHA-1 is used. They will be replaced in due course by SHA-3, using an algorithm that has not yet been selected.

SSL Secure Sockets Layer, the cryptographic system used in HTTPS for key exchange and secure communications.

sypware Malware that reports on the user's computer activity to someone else.

stateless In software, a program or protocol is stateless if it does not rely on storing values internally for retrieval in a later stage. A stateless Web service may use external storage to track interactions, such as a cookie on the user's computer.

Theme An addon-type file that changes the overall appearance of your Firefox browser

URL or uniform resource locator A special, unique name for a page or other content on the Web. A URL contains at least a "type" such as http, followed by ":", and an address. The address can be a Web address (, an e-mail address (, or any other as specified for the protocol indicated by the type. URLs may contain only ASCII printing characters.

zombie computer A computer that has been taken over by malware and used for attacks on other computers.