unleashed-firmware/applications/external/totp/services/totp/totp.c

104 lines
3.1 KiB
C

#include "totp.h"
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#include <timezone_utils.h>
#include "../hmac/hmac_sha1.h"
#include "../hmac/hmac_sha256.h"
#include "../hmac/hmac_sha512.h"
#include "../hmac/byteswap.h"
#define HMAC_MAX_RESULT_SIZE HMAC_SHA512_RESULT_SIZE
/**
* @brief Generates the timeblock for a time in seconds.
* Timeblocks are the amount of intervals in a given time. For example,
* if 1,000,000 seconds has passed for 30 second intervals, you would get
* 33,333 timeblocks (intervals), where timeblock++ is effectively +30 seconds.
* @param interval in seconds
* @param for_time a time in seconds to get the current timeblocks
* @return Timeblock given \p for_time using \p interval
*/
uint64_t totp_timecode(uint8_t interval, uint64_t for_time) {
return for_time / interval;
}
/**
* @brief Generates an OTP (One Time Password)
* @param algo hashing algorithm to be used
* @param plain_secret plain token secret
* @param plain_secret_length plain token secret length
* @param input input data for OTP code generation
* @return OTP code if code was successfully generated; 0 otherwise
*/
uint64_t otp_generate(
TOTP_ALGO algo,
const uint8_t* plain_secret,
size_t plain_secret_length,
uint64_t input) {
uint8_t hmac[HMAC_MAX_RESULT_SIZE] = {0};
uint64_t input_swapped = swap_uint64(input);
int hmac_len =
(*algo)(plain_secret, plain_secret_length, (uint8_t*)&input_swapped, 8, &hmac[0]);
if(hmac_len == 0) {
return OTP_ERROR;
}
uint64_t offset = (hmac[hmac_len - 1] & 0xF);
uint64_t i_code =
((hmac[offset] & 0x7F) << 24 | (hmac[offset + 1] & 0xFF) << 16 |
(hmac[offset + 2] & 0xFF) << 8 | (hmac[offset + 3] & 0xFF));
return i_code;
}
uint64_t totp_at(
TOTP_ALGO algo,
const uint8_t* plain_secret,
size_t plain_secret_length,
uint64_t for_time,
float timezone,
uint8_t interval) {
uint64_t for_time_adjusted =
timezone_offset_apply(for_time, timezone_offset_from_hours(timezone));
return otp_generate(
algo, plain_secret, plain_secret_length, totp_timecode(interval, for_time_adjusted));
}
static int totp_algo_sha1(
const uint8_t* key,
size_t key_length,
const uint8_t* input,
size_t input_length,
uint8_t* output) {
hmac_sha1(key, key_length, input, input_length, output);
return HMAC_SHA1_RESULT_SIZE;
}
static int totp_algo_sha256(
const uint8_t* key,
size_t key_length,
const uint8_t* input,
size_t input_length,
uint8_t* output) {
hmac_sha256(key, key_length, input, input_length, output);
return HMAC_SHA256_RESULT_SIZE;
}
static int totp_algo_sha512(
const uint8_t* key,
size_t key_length,
const uint8_t* input,
size_t input_length,
uint8_t* output) {
hmac_sha512(key, key_length, input, input_length, output);
return HMAC_SHA512_RESULT_SIZE;
}
const TOTP_ALGO TOTP_ALGO_SHA1 = (TOTP_ALGO)(&totp_algo_sha1);
const TOTP_ALGO TOTP_ALGO_SHA256 = (TOTP_ALGO)(&totp_algo_sha256);
const TOTP_ALGO TOTP_ALGO_SHA512 = (TOTP_ALGO)(&totp_algo_sha512);