Obfuscation

Obfuscation is the obscuring of the intended meaning of communication by making the message difficult to understand, usually with confusing and ambiguous language. The obfuscation might be either unintentional or intentional (although intent usually is connoted), and is accomplished with circumlocution (talking around the subject), the use of jargon (technical language of a profession), and the use of an argot (ingroup language) of limited communicative value to outsiders.
In expository writing, unintentional obfuscation usually occurs in draft documents, at the beginning of composition; such obfuscation is illuminated with critical thinking and editorial revision, either by the writer or by an editor. Etymologically, the word "obfuscation" derives from the Latin , from "obfuscāre" (to darken); synonyms include the words beclouding and abstrusity.
Background.
Doctors are faulted for using jargon to conceal unpleasant facts from a patient; the American author and physician Michael Crichton said that medical writing is a "highly skilled, calculated attempt to confuse the reader". The psychologist B. F. Skinner said that medical notation is a form of multiple audience control, which allows the doctor to communicate to the pharmacist things which the patient might oppose if they could understand medical jargon.
Eschew.
"Eschew obfuscation", also stated as "eschew obfuscation, espouse elucidation", is a humorous fumblerule used by English teachers and professors when lecturing about proper writing techniques. Literally, the phrase means "avoid being unclear" or "avoid being unclear, support being clear", but the use of relatively uncommon words causes confusion in much of the audience (those lacking the vocabulary), making the statement an example of irony, and more precisely a heterological phrase. The phrase has appeared in print at least as early as 1959, when it was used as a section heading in a NASA document.
An earlier similar phrase appears in Mark Twain's "Fenimore Cooper's Literary Offenses", where he lists rule fourteen of good writing as "eschew surplusage".
Secure communication.
Obfuscation of oral or written communication achieves a degree of secure communication without a need to rely upon technology. This technique is sometimes referred to as "talking around" and is a form of security through obscurity.
A notable example of obfuscation of written communication is a message sent by September 11 attacks ringleader Mohamed Atta to other conspirators prior to the attacks occurring:
In this obfuscated message, the following code words are believed to exist:
Within the illegal drug trade, obfuscation is commonly used in communication to hide the occurrence of drug trafficking. A notable example is the use of "420" as a code word to refer to cannabis consumption, an activity which despite legalisation changes, was once illegal in most jurisdictions. The Drug Enforcement Administration reported in July 2018 a total of 353 different code words used for cannabis.
White box cryptography.
In white-box cryptography, obfuscation refers to the protection of cryptographic keys from extraction when they are under the control of the adversary, e.g., as part of a DRM scheme.
Network security.
In network security, obfuscation refers to methods used to obscure an attack payload from inspection by network protection systems.