58 lines
2.3 KiB
Markdown
58 lines
2.3 KiB
Markdown
TOTP Pure C Library for ALL MCU
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====================
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Library to generate Time-based One-Time Passwords.
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Implements the Time-based One-Time Password algorithm specified in [RFC 6238](https://tools.ietf.org/html/rfc6238).
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Supports different time steps and is compatible with tokens that use the same standard (including software ones, like the Google Authenticator app).
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Tested on MCUs: MSP430, RP2040
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Installation & usage:
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--------------------
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First include header to your file
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```
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#include <totp.h>
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```
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After included, define key ex. Key is ```MyLegoDoor```
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- Note: The format of hmacKey is array of hexadecimal bytes.
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- Most websites provide the key encoded in base32 - RFC3548/RFC4648, either upper or lower case. You can use [this site](https://cryptii.com/pipes/base32-to-hex) to convert the base32 string to hex (make sure you upcase it first if it's lowercase and remove all whitespaces).
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```
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uint8_t hmacKey[] = {0x4d, 0x79, 0x4c, 0x65, 0x67, 0x6f, 0x44, 0x6f, 0x6f, 0x72}; // Secret key
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```
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Instantiate the TOTP class by providing the secret hmacKey, the length of the hmacKey and the Timestep between codes.
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```
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TOTP(hmacKey, 10, 30); // Secret key, Secret key length, Timestep (30s)
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```
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Use the ```getCodeFromTimestamp()``` function to get a TOTP from a unix epoch timestamp
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```
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uint32_t newCode = getCodeFromTimestamp(1557414000); // Current timestamp since Unix epoch in seconds
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```
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Or ```getCodeFromTimeStruct()``` if you want to get a TOTP from a tm struct (Time Struct in C),
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```
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struct tm datetime;
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datetime.tm_hour = 9;
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datetime.tm_min = 0;
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datetime.tm_sec = 0;
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datetime.tm_mday = 13;
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datetime.tm_mon = 5;
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datetime.tm_year = 2019;
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uint32_t newCode = getCodeFromTimeStruct(datetime);
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```
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If the provided unix timestamp isn't in UTC±0, use ```setTimezone()``` before ```getCodeFromTimestamp()``` or ```getCodeFromTimeStruct()``` to offset the time.
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```
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setTimezone(9); // Set timezone +9 Japan
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```
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You can see an example in blink.c
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Thanks to:
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----------
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* Jose Damico, https://github.com/damico/ARDUINO-OATH-TOKEN
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* Peter Knight, https://github.com/Cathedrow/Cryptosuite
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* Maniacbug, https://github.com/maniacbug/Cryptosuite
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* lucadentella, https://github.com/lucadentella/TOTP-Arduino
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