NAME

       oath_hotp_generate - API function

SYNOPSIS

       #include <oath.h>

       int  oath_hotp_generate(const char * secret, size_t secret_length, uint64_t moving_factor,
       unsigned digits, bool add_checksum, size_t truncation_offset, char * output_otp);

ARGUMENTS

       const char * secret
                   the shared secret string

       size_t secret_length
                   length of secret

       uint64_t moving_factor
                   a counter indicating the current OTP to generate

       unsigned digits
                   number of requested digits in the OTP, excluding checksum

       bool add_checksum
                   whether to add a checksum digit or not

       size_t truncation_offset
                   use a specific truncation offset

       char * output_otp
                   output buffer, must have room for the output OTP plus zero

DESCRIPTION

       Generate a one-time-password using the HOTP algorithm as described in RFC 4226.

       Use a value of OATH_HOTP_DYNAMIC_TRUNCATION for truncation_offset unless you really need a
       specific truncation offset.

       To  find out the size of the OTP you may use the OATH_HOTP_LENGTH() macro.  The output_otp
       buffer must be have room for that length plus one for the terminating NUL.

       Currently only values 6, 7 and 8 for digits are supported, and the add_checksum  value  is
       ignored.   These  restrictions may be lifted in future versions, although some limitations
       are inherent in the protocol.

RETURNS

       On success, OATH_OK (zero) is returned, otherwise an error code is returned.

REPORTING BUGS

       Report     bugs     to     <oath-toolkit-help@nongnu.org>.      liboath     home     page:
       https://www.nongnu.org/oath-toolkit/      General     help     using     GNU     software:
       http://www.gnu.org/gethelp/

COPYRIGHT

       Copyright © 2009-2020 Simon Josefsson.
       Copying and distribution of this file, with or without modification, are permitted in  any
       medium without royalty provided the copyright notice and this notice are preserved.