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Libhotp API Reference Manual | |
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Top | Description |
#define HOTPAPI #define HOTP_VERSION #define HOTP_VERSION_MAJOR #define HOTP_VERSION_MINOR #define HOTP_VERSION_PATCH #define HOTP_VERSION_NUMBER enum hotp_rc; #define HOTP_DYNAMIC_TRUNCATION #define HOTP_OTP_LENGTH (digits, checksum) int hotp_init (void); int hotp_done (void); const char * hotp_check_version (const char *req_version); int hotp_hex2bin (char *hexstr, char *binstr, size_t *binlen); int hotp_generate_otp (const char *secret, size_t secret_length, uint64_t moving_factor, unsigned digits, bool add_checksum, size_t truncation_offset, char *output_otp); int hotp_validate_otp (const char *secret, size_t secret_length, uint64_t start_moving_factor, size_t window, const char *otp); int hotp_authenticate_usersfile (const char *usersfile, const char *username, const char *otp, size_t window, const char *passwd, time_t *last_otp);
# define HOTP_VERSION "1.0.0"
Pre-processor symbol with a string that describe the header file
version number. Used together with hotp_check_version()
to verify
header file and run-time library consistency.
# define HOTP_VERSION_MAJOR 0
Pre-processor symbol with a decimal value that describe the major level of the header file version number. For example, when the header version is 1.2.3 this symbol will be 1.
# define HOTP_VERSION_MINOR 0
Pre-processor symbol with a decimal value that describe the minor level of the header file version number. For example, when the header version is 1.2.3 this symbol will be 2.
# define HOTP_VERSION_PATCH 0
Pre-processor symbol with a decimal value that describe the patch level of the header file version number. For example, when the header version is 1.2.3 this symbol will be 3.
# define HOTP_VERSION_NUMBER 0x010000
Pre-processor symbol with a hexadecimal value describing the header file version number. For example, when the header version is 1.2.3 this symbol will have the value 0x010203.
typedef enum { HOTP_OK = 0, HOTP_CRYPTO_ERROR = -1, HOTP_INVALID_DIGITS = -2, HOTP_PRINTF_ERROR = -3, HOTP_INVALID_HEX = -4, HOTP_TOO_SMALL_BUFFER = -5, HOTP_INVALID_OTP = -6, HOTP_REPLAYED_OTP = -7, HOTP_BAD_PASSWORD = -8, HOTP_INVALID_COUNTER = -9, HOTP_INVALID_TIMESTAMP = -10, HOTP_NO_SUCH_FILE = -11, HOTP_UNKNOWN_USER = -12, HOTP_FILE_SEEK_ERROR = -13, HOTP_FILE_CREATE_ERROR = -14, HOTP_FILE_LOCK_ERROR = -15, HOTP_FILE_RENAME_ERROR = -16, HOTP_FILE_UNLINK_ERROR = -17, HOTP_TIME_ERROR = -18, } hotp_rc;
Return codes for HOTP functions. All return codes are negative except for the successful code HOTP_OK which are guaranteed to be 0. Positive values are reserved for non-error return codes.
Note that the hotp_rc enumeration may be extended at a later date to include new return codes.
Successful return | |
Internal error in crypto functions | |
Unsupported number of OTP digits | |
Error from system printf call | |
Hex string is invalid | |
The output buffer is too small | |
The OTP is not valid | |
The OTP has been replayed | |
The password does not match | |
The counter value is corrupt | |
The timestamp is corrupt | |
The supplied filename does not exist | |
Cannot find information about user | |
System error when seeking in file | |
System error when creating file | |
System error when locking file | |
System error when renaming file | |
System error when removing file | |
System error for time manipulation |
#define HOTP_OTP_LENGTH(digits, checksum) (digits + (checksum ? 1 : 0))
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int hotp_init (void);
This function initializes the HOTP library. Every user of this
library needs to call this function before using other functions.
You should call hotp_done()
when use of the HOTP library is no
longer needed.
Note that this function may also initialize Libgcrypt, if the HOTP library is built with libgcrypt support and libgcrypt has not been initialized before. Thus if you want to manually initialize libgcrypt you must do it before calling this function. This is useful in cases you want to disable libgcrypt's internal lockings etc.
Returns : |
On success, HOTP_OK (zero) is returned, otherwise an
error code is returned.
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int hotp_done (void);
This function deinitializes the HOTP library, which were
initialized using hotp_init()
. After calling this function, no
other HOTP library function may be called except for to
re-initialize the library using hotp_init()
.
Returns : |
On success, HOTP_OK (zero) is returned, otherwise an
error code is returned.
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const char * hotp_check_version (const char *req_version);
Check HOTP library version.
See HOTP_VERSION
for a suitable req_version
string.
This function is one of few in the library that can be used without
a successful call to hotp_init()
.
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version string to compare with, or NULL .
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Returns : |
Check that the version of the library is at
minimum the one given as a string in req_version and return the
actual version string of the library; return NULL if the
condition is not met. If NULL is passed to this function no
check is done and only the version string is returned.
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int hotp_hex2bin (char *hexstr, char *binstr, size_t *binlen);
Convert string with hex data to binary data.
Non-hexadecimal data are not ignored but instead will lead to an
HOTP_INVALID_HEX
error.
If binstr
is NULL
, then binlen
will be populated with the
necessary length. If the binstr
buffer is too small,
HOTP_TOO_SMALL_BUFFER
is returned and binlen
will contain the
necessary length.
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input string with hex data |
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output string that holds binary data, or NULL
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output variable holding needed length of binstr
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Returns : |
On success, HOTP_OK (zero) is returned, otherwise an
error code is returned.
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int hotp_generate_otp (const char *secret, size_t secret_length, uint64_t moving_factor, unsigned digits, bool add_checksum, size_t truncation_offset, char *output_otp);
Generate a one-time-password using the HOTP algorithm as described in RFC 4226.
Use a value of 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 HOTP_OTP_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.
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the shared secret string |
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length of secret
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a counter indicating the current OTP to generate |
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number of requested digits in the OTP, excluding checksum |
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whether to add a checksum digit or not |
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use a specific truncation offset |
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output buffer, must have room for the output OTP plus zero |
Returns : |
On success, HOTP_OK (zero) is returned, otherwise an
error code is returned.
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int hotp_validate_otp (const char *secret, size_t secret_length, uint64_t start_moving_factor, size_t window, const char *otp);
Validate an OTP according to OATH HOTP algorithm per RFC 4226.
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.
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the shared secret string |
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length of secret
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start counter in OTP stream |
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how many OTPs from start counter to test |
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the OTP to validate. |
Returns : |
Returns position in OTP window (zero is first position),
or HOTP_INVALID_OTP if no OTP was found in OTP window, or an
error code.
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int hotp_authenticate_usersfile (const char *usersfile, const char *username, const char *otp, size_t window, const char *passwd, time_t *last_otp);
Authenticate user named username
with the one-time password otp
and (optional) password passwd
. Credentials are read (and
updated) from a text file named usersfile
.
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string with user credential filename, in UsersFile format |
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string with name of user |
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string with one-time password to authenticate |
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how many future OTPs to search |
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string with password, or NULL to disable password checking
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output variable holding last successful authentication |
Returns : |
On successful validation, HOTP_OK is returned. If the
supplied otp is the same as the last successfully authenticated
one-time password, HOTP_REPLAYED_OTP is returned and the
timestamp of the last authentication is returned in last_otp .
If the one-time password is not found in the indicated search
window, HOTP_INVALID_OTP is returned. Otherwise, an error code
is returned.
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