Transaction authentication number
type of one time password
A transaction authentication number (TAN) is used by some online banking services as a form of single use one-time passwords (OTPs) to authorize financial transactions. TANs are a second layer of security above and beyond the traditional single-password authentication.
TANs provide additional security because they act as a form of two-factor authentication (2FA). If the physical document or token containing the TANs is stolen, it will be useless without the password. Conversely, if the login data are obtained, no transactions can be performed without a valid TAN.
Classic TAN
TANs often function as follows:
The bank creates a set of unique TANs for the user. Typically, there are 50 TANs printed on a list, enough to last half a year for a normal user; each TAN being six or eight characters long.
The user picks up the list from the nearest bank branch (presenting a passport, an ID card or similar document) or is sent the TAN list through mail.
The password (PIN) is mailed separately.
To log on to their account, the user must enter user name (often the account number) and password (PIN). This may give access to account information but the ability to process transactions is disabled.
The public source identifies “Transaction authentication number” as type of one time password. This brief keeps that definition visible, then builds a research path around Transaction, authentication and number.
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This entry incorporates text from “Transaction authentication number” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.