User authentication system by using touch pattern

PURPOSE: A user authentication system and method using touch patterns are provided to determine a random key arrangement using a separate encoding variable, and arrange a virtual keyboard according to the determined random key arrangement. CONSTITUTION: A communication unit (150) performs a wireless communication with a transaction server. A user authentication processing unit (140) transmits the coordinates of a pattern password and an encoding variable to the transaction server via the communication unit. The transaction server receives the encoding variable and the coordinates of the pattern password from a terminal, and performs decoding based on the received information. If the decoded pattern password is equal to a pre-stored pattern password of a user, the transaction server grants the user authentication. [Reference numerals] (110) Encoding table; (120) Code processing unit; (130) Display unit; (140) User authentication processing unit; (150) Communication unit