Methods and systems for authenticating a client device using entropy provided by a server and/or a device paired with the client device are described herein. The system may generate static entropy and time-limited entropy based on data from the server and/or the paired device. The static and time-limited entropy may be used to authenticate the client device (application or a user of the client device) in addition to authentication credentials or entropy such as a PIN or password provided by the user. The time-limited entropy may have an expiration time. If the time-limited entropy is expired, the system may request the user to perform a hard authentication with the server, such as by providing a username, password, and/or optionally a two-factor authentication code, among other information.