.\" DO NOT MODIFY THIS FILE!  It was generated by gdoc.
.TH "oath_hotp_generate" 3 "2.6.11" "liboath" "liboath"
.SH NAME
oath_hotp_generate \- API function
.SH SYNOPSIS
.B #include <oath.h>
.sp
.BI "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 ");"
.SH ARGUMENTS
.IP "const char * secret" 12
the shared secret string
.IP "size_t secret_length" 12
length of \fIsecret\fP
.IP "uint64_t moving_factor" 12
a counter indicating the current OTP to generate
.IP "unsigned digits" 12
number of requested digits in the OTP, excluding checksum
.IP "bool add_checksum" 12
whether to add a checksum digit or not
.IP "size_t truncation_offset" 12
use a specific truncation offset
.IP "char * output_otp" 12
output buffer, must have room for the output OTP plus zero
.SH "DESCRIPTION"
Generate a one\-time\-password using the HOTP algorithm as described
in RFC 4226.

Use a value of \fBOATH_HOTP_DYNAMIC_TRUNCATION\fP for \fItruncation_offset\fP
unless you really need a specific truncation offset.

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

Currently only values 6, 7 and 8 for \fIdigits\fP are supported, and the
\fIadd_checksum\fP value is ignored.  These restrictions may be lifted
in future versions, although some limitations are inherent in the
protocol.
.SH "RETURNS"
On success, \fBOATH_OK\fP (zero) is returned, otherwise an
error code is returned.
.SH "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/
.SH COPYRIGHT
Copyright \(co 2009-2020 Simon Josefsson.
.br
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.