n. A technique in which a person obtains confidential information by pretending to be someone who has legitimate access to that information.
Other Forms
Pretexting has long been a tactic used by private investigators and others to obtain personal information and records about people. Also known as "social engineering" in the hacker realm, it involves using ploys to obtain data and documents.
—Kim Zetter, “Protect Yourself From Pretexting,” Wired News, September 13, 2006
You see the object of your desire get up from her desk to go to the cafeteria, and decide it’s time for lunch. You follow her to the salad bar (you hate salad). But you fill your plate and say: "What a coincidence! I like tofu drenched in Thousand Island, too. Are you busy Friday night?"

You have just "pretexted." You have misrepresented yourself to establish a connection and achieve your real end. You also have something in common with the sometimes shadowy world of private detectives.

The concept of pretexting came into the news in the last week in light of a scandal gripping Hewlett-Packard. The computer company hired investigators to discover which member of its board of directors leaked information to reporters.

To help track down the leaker, the private investigators obtained the phone records of board members and journalists by calling up phone companies and pretending to be those people.
—Matt Richtel, “The Secret Life of Private Investigators,” The New York Times, September 17, 1992
1992 (earliest)
In the underground market for personal information, the going rate for your 10-year earnings history is $175.

That price tag surfaced in an 18-month federal investigation of a nationwide ring of "information brokers" who allegedly bribed Social Security Administration employees to make computer searches for the records of thousands of people. According to officials, the alleged SSA accomplices receive $25 per record, but the broker gives it a big markup and sells the information to private investigators, creditors and businesses for $175. …

Morey said brokers typically have one or more SSA employees "under contract" and pay $25 for each earnings history. Another technique, called "pretexting," is to get the data by phone after claiming to be an SSA employee from another office where the computer is down.
—Mitch Betts, “Personal data more public than you think,” Computerworld, March 09, 1992