JustOnce

A framework for one-time password (OTP) generation.

Setup

Clone the repository recursively:

git clone --recursive https://github.com/think-biq/JustOnce .

To build the library:

make

Will generate the build environment to ./staging through cmake, and builds the library.

To run the tests:

make run-test

Will build a test executable using the testly test library.

To generate doxygen documentation:

make docs

Will build doxygen html output and put it into docs/html.

Examples

Create TOTP

#include <JustOnce/otp.h>
#include <stdio.h>

int main(void)
{
	int Digits = 6;
	int64_t Timestamp = 433512000;
	int64_t Interval = 30;	
	otp_error_t State;

	// Generates random OTP key (32 character long base32 encoded string).
	char* Key = GenerateKey();
	printf("Generating TOTP using Key '%s' ...\n", Key);
	// Generates time-based one-time password.
	int TOTP = CalculateTOTP(Key, Timestamp, Interval, Digits, &State);
	free(Key);

	// Converts otp code to string and prepends zeros if necessary (depending on digit count).
	char* Code = MakeStringFromOTP(TOTP, Digits);
	printf("TOTP: %s (State: %s)\n", Code, GetErrorName(State));
	free(Code);

}

Other examples

Feel free to stroll through the tests, to see further usage examples.

Modules

For detailed documentation, consider building doxygen html documentation.

HMAC

Offers a SHA1 based HMAC generation.

Key

Functionallity to generate and validate keys to be used for OTP generation.

Misc

String case functions and url encoding.

OTP

Generation and validation of one-time passwords.

Timing

Time utility functions to fetch unix timestamp and generate TOTP periods.