Learn in the textbookUser Authentication (Knowledge-Based and Possession-Based)
DefinitionA one-time password (ワンタイムパスワード) is a single-use password valid for one authentication only, and a new value is issued every time.
ExplanationThe value is generated, for example, by a small dedicated device called a token (トークン) or by a smartphone app, or it is sent by SMS. Two other methods follow the same idea, because the value entered changes with each authentication: typing the digits at positions, different each time, specified on a pre-issued random number table (乱数表), and matrix authentication (マトリクス認証), where different digits appear each time in a grid at positions and in an order the user has memorized.
AnalogyIt is like the numbered ticket you take at a bank counter: once your number is called, it is done, and on your next visit you get a different one.
Memory hook"One-time" means good for one use only, the opposite of an ordinary password that you can use again and again.