GY-63_MS5611/libraries/LUHN

LUHN

Arduino Library for calculating LUHN checksum.

Description

The LUHN algorithm is a checksum (a.k.a. mod 10) invented by Hans Peter Luhn in 1960. It is used to validate a variety of product ID's to detect typing errors an/of digit swaps. So it is not to secure a number but to prevent common mistakes when entering a code in a system. The LUHN check uses very few resources and is pretty fast.

Basic idea is to put all digits-1 through the formula and the output should equal the last digit.

Note: some LUHN validations uses the reversed product string.

• https://en.wikipedia.org/wiki/Luhn_algorithm

related

• https://github.com/RobTillaart/Adler
• https://github.com/RobTillaart/CRC
• https://github.com/RobTillaart/Fletcher
• https://github.com/RobTillaart/LUHN

Interface

#include "LUHN.h"

• LUHN() constructor
• bool isValid(char * buffer ) validates the code in the parameter buffer. The parameter buffer is a '\0' terminated char array. Length should be less than 254.
• bool isValid(const char * buffer ) idem.
• char generateChecksum(char * buffer) Returns the char '0'..'9' which is the checksum of the code in the parameter buffer. The parameter buffer is a '\0' terminated char array. Length should be less than 254.
• bool generate(char * buffer, uint8_t length, char * prefix) Generates a char array including LUHN number with a defined prefix of max length. Returns false if the prefix exceeds length -1.

Stream

• char add(char c) add char, return LUHN so far.
• char reset() return last LUHN.

The internal counter for the stream interface is 16 bit. This limits the nr of add() calls to about 65530. (if this is a problem, make it an uinit32_t)

Future

must

• update documentation

should

• unit tests
• look for optimization

could

• uint32_t interface for up to 8 digit ID's (99.999.999)
  • isValid(uint32_t)
  • generateChecksum(uint32_t)
  • how about leading zero's