HashGenerator Class Reference

Wrapper class which allows generating a hash of a given type from any arbitrary byte payload, which is hashable in chunks. More...

#include <HashGenerator.h>

Classes
struct	HashString
	Wrapper class for the char array that is big enough to hold the string representation of every possible hash algorithm. More...

Public Member Functions
	HashGenerator (void)=default
	Constructor. More...
	HashGenerator (HashGenerator const &other)=delete
	Deleted copy constructor. More...
void	operator= (HashGenerator const &other)=delete
	Deleted copy assignment operator. More...
	~HashGenerator (void)
	Destructor. More...
bool	start (mbedtls_md_type_t const &type)
	Starts the hashing process. More...
bool	update (uint8_t const *data, size_t const &length)
	Update the current hash value with new data. More...
HashString	finish ()
	Calculates the final hash string representation and stops the hash calculation no further calls to update() will work, instead the same context can be reused to start another hash calculation operation with start() More...

Detailed Description

Wrapper class which allows generating a hash of a given type from any arbitrary byte payload, which is hashable in chunks.

Note

The class wraps around either the Arduino Seeed mbedtls library from Seed Studio (https://github.com/Seeed-Studio/Seeed_Arduino_mbedtls) or the offical ESP Mbed TLS implementation from Mbed TLS (https://github.com/Mbed-TLS/mbedtls), the latter takes precendence if it exists. This is done because it removes the need to include another library, because the component already exists on the system and we can therefore simply utilize that one. The ESP Mbed TLS implementationt works with both Espressif IDF v4.X and v5.X, meaning it is version idependent, this is the case because depending on the used version the implementation automatically adjusts to still initalize correctly. The class instance is meant to be started with start() which will then create the configuration for a hash of the given type and we then expect the complete binary payload to be called in multiple calls to update() and the final result to be read with finish(). Documentation about the specific use and caviates of the ESP Mbedt TLS implementation can be found here https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/protocols/mbedtls.html

Constructor & Destructor Documentation

HashGenerator() [1/2]

HashGenerator::HashGenerator ( void  )

default

Constructor.

HashGenerator() [2/2]

HashGenerator::HashGenerator ( HashGenerator const &  other )

delete

Deleted copy constructor.

Note

Copying an active HashGenerator is not possible and there are no settings or configuration to copy. Therefore copying is disabled alltogether

Parameters

other

Other instance we disallow copying from

~HashGenerator()

HashGenerator::~HashGenerator

(

void

)

Destructor.

Member Function Documentation

finish()

HashGenerator::HashString HashGenerator::finish

(

)

Calculates the final hash string representation and stops the hash calculation no further calls to update() will work, instead the same context can be reused to start another hash calculation operation with start()

Returns

Hash string representation of the previously entered hashed binary data, if the hashing process failed the hash string representation will be empty

operator=()

void HashGenerator::operator= ( HashGenerator const &  other )

delete

Deleted copy assignment operator.

Note

Copying an active HashGenerator is not possible and there are no settings or configuration to copy. Therefore copying is disabled alltogether

Parameters

other

Other instance we disallow copying from

start()

bool HashGenerator::start

(

mbedtls_md_type_t const &

type

)

Starts the hashing process.

Parameters

type	Supported type of hash that should be generated from the given binary data

Returns

Whether initalizing and starting the hash calculation was successful or not

update()

bool HashGenerator::update	(	uint8_t const *	data,
		size_t const &	length
	)

Update the current hash value with new data.

Parameters

data	Non owning pointer to the data that should be added to generate the hash. Does not need to kept alive as the update function copies the data by writing it into the hash function storage
length	Length of data entered

Returns

Whether updating the hash for the given bytes was successful or not

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The documentation for this class was generated from the following files:

• src/HashGenerator.h
• src/HashGenerator.cpp