re structure

lib/totp/totp.cpp

@@ -0,0 +1,76 @@
+#include <sha1.hpp>
+#include "totp.hpp"
+
+uint8_t *_hmacKey;
+uint8_t _keyLength;
+uint8_t _timeZoneOffset = 0;
+uint32_t _timeStep;
+
+// Init the library with the private key, its length and the timeStep duration
+void TOTP(uint8_t *hmacKey, uint8_t keyLength, uint32_t timeStep)
+{
+    _hmacKey = hmacKey;
+    _keyLength = keyLength;
+    _timeStep = timeStep;
+}
+
+void setTimezone(uint8_t timezone)
+{
+    _timeZoneOffset = timezone;
+}
+
+uint32_t TimeStruct2Timestamp(struct tm time)
+{
+    // time.tm_mon -= 1;
+    // time.tm_year -= 1900;
+    return mktime(&(time)) - (_timeZoneOffset * 3600) - 2208988800;
+}
+
+// Generate a code, using the timestamp provided
+uint32_t getCodeFromTimestamp(uint32_t timeStamp)
+{
+    uint32_t steps = timeStamp / _timeStep;
+    return getCodeFromSteps(steps);
+}
+
+// Generate a code, using the timestamp provided
+uint32_t getCodeFromTimeStruct(struct tm time)
+{
+    return getCodeFromTimestamp(TimeStruct2Timestamp(time));
+}
+
+// Generate a code, using the number of steps provided
+uint32_t getCodeFromSteps(uint32_t steps)
+{
+    // STEP 0, map the number of steps in a 8-bytes array (counter value)
+    uint8_t _byteArray[8];
+    _byteArray[0] = 0x00;
+    _byteArray[1] = 0x00;
+    _byteArray[2] = 0x00;
+    _byteArray[3] = 0x00;
+    _byteArray[4] = (uint8_t)((steps >> 24) & 0xFF);
+    _byteArray[5] = (uint8_t)((steps >> 16) & 0xFF);
+    _byteArray[6] = (uint8_t)((steps >> 8) & 0XFF);
+    _byteArray[7] = (uint8_t)((steps & 0XFF));
+
+    // STEP 1, get the HMAC-SHA1 hash from counter and key
+    initHmac(_hmacKey, _keyLength);
+    writeArray(_byteArray, 8);
+    uint8_t *_hash = resultHmac();
+
+    // STEP 2, apply dynamic truncation to obtain a 4-bytes string
+    uint32_t _truncatedHash = 0;
+    uint8_t _offset = _hash[20 - 1] & 0xF;
+    uint8_t j;
+    for (j = 0; j < 4; ++j)
+    {
+        _truncatedHash <<= 8;
+        _truncatedHash |= _hash[_offset + j];
+    }
+
+    // STEP 3, compute the OTP value
+    _truncatedHash &= 0x7FFFFFFF; // Disabled
+    _truncatedHash %= 1000000;
+
+    return _truncatedHash;
+}