oath_hotp_generate (3) - Linux Manuals

oath_hotp_generate: API function


oath_hotp_generate - API function


#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);


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


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.


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


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


Copyright © 2009-2012 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.