File Content: FILEFORMAT All configuration data and state is kept in ~/.google_authenticator The file is all ASCII, but is kept in a very simple-to-parse and rigid file format. The file size is currently limited to 1kB. This should be generous even when using a very large list of scratch codes. The first line is the base32 encoded secret. It uses characters in the range A..Z2..7. The secret is used after first trying any one-time scratch codes. HOTP mode is used only if HOTP_COUNTER is present. TOTP mode is used only if TOTP_AUTH is present *and* HOTP_COUNTER is not present. The following lines are optional. They all start with a double quote character, followed by a space character. Followed by an option name. Option names are all upper-case and must include an underscore. This ensures that they cannot accidentally appear anywhere else in the file. Options can be followed by option-specific parameters. Currently, the following options are recognized: DISALLOW_REUSE if present, this signals that a time-based token can be used at most once. Any attempt to log in using the same token will be denied. This means that users can typically not log in faster than once every ~30 seconds. The option is followed by a space-separated list of time stamps that have previously been used for login attempts. This option has no effect when HOTP_COUNTER is present. RATE_LIMIT n m ... this optional parameter restricts the number of logins to at most "n" within each "m" second interval. Additional parameters in this line are undocumented; they are used internally to keep track of state. TOTP_AUTH the presence of this option indicates that the secret can be used to authenticate users with a time-based token. STEP_SIZE n the number of seconds in each time step during which a TOTP code is valid. The default is that a code is valid for 30 seconds. HOTP_COUNTER n the presence of this option indicates that the secret can be used to authenticate users with a counter-based token. The argument "n" represents which counter value the token will accept next. It should be initialized to 1. WINDOW_SIZE n the default window size is 3, allowing up to one extra valid token before and after the currently active one. This might be too restrictive if the client and the server experience significant time skew. You can provide a parameter to increase the login window size from 3 to "n" In counter-based mode, this option is the number of valid tokens after the currently active one. The default is almost certainly too restrictive for most users as invalid login attempts and generated-but-not-used tokens both contribute to synchronization problems. Any all-numeric sequence of eight-digit numbers are randomly generated one-time scratch code tokens. The user can enter any arbitrary one-time code to log into his account. The code will then be removed from the file. Submit