.\" DO NOT MODIFY THIS FILE!  It was generated by gdoc.
.TH "oath_totp_validate4" 3 "2.6.7" "liboath" "liboath"
.SH NAME
oath_totp_validate4 \- API function
.SH SYNOPSIS
.B #include <oath.h>
.sp
.BI "int oath_totp_validate4(const char * " secret ", size_t " secret_length ", time_t " now ", unsigned " time_step_size ", time_t " start_offset ", size_t " window ", int * " otp_pos ", uint64_t * " otp_counter ", int " flags ", const char * " otp ");"
.SH ARGUMENTS
.IP "const char * secret" 12
the shared secret string
.IP "size_t secret_length" 12
length of \fIsecret\fP
.IP "time_t now" 12
Unix time value to validate TOTP for
.IP "unsigned time_step_size" 12
time step system parameter (typically 30)
.IP "time_t start_offset" 12
Unix time of when to start counting time steps (typically 0)
.IP "size_t window" 12
how many OTPs after/before start OTP to test
.IP "int * otp_pos" 12
output search position in search window (may be NULL).
.IP "uint64_t * otp_counter" 12
counter value used to calculate OTP value (may be NULL).
.IP "int flags" 12
flags indicating mode, one of \fBoath_totp_flags\fP
.IP "const char * otp" 12
the OTP to validate.
.SH "DESCRIPTION"
Validate an OTP according to OATH TOTP algorithm per RFC 6238.

Currently only OTP lengths of 6, 7 or 8 digits are supported.  This
restrictions may be lifted in future versions, although some
limitations are inherent in the protocol.

The \fIflags\fP parameter may be used to change the MAC function, for
example \fBOATH_TOTP_HMAC_SHA256\fP or \fBOATH_TOTP_HMAC_SHA512\fP.
.SH "RETURNS"
Returns absolute value of position in OTP window (zero is
first position), or \fBOATH_INVALID_OTP\fP if no OTP was found in OTP
window, or an error code.
.SH "SINCE"
2.6.0
.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.