QCA::MessageAuthenticationCode Class Reference

#include <QtCrypto>

Collaboration diagram for QCA::MessageAuthenticationCode:

Public Member Functions
void	clear () override
MemoryRegion	final () override
KeyLength	keyLength () const
	MessageAuthenticationCode (const MessageAuthenticationCode &from)
	MessageAuthenticationCode (const QString &type, const SymmetricKey &key, const QString &provider=QString())
MessageAuthenticationCode &	operator= (const MessageAuthenticationCode &from)
void	setup (const SymmetricKey &key)
QString	type () const
void	update (const MemoryRegion &array) override
bool	validKeyLength (int n) const
Public Member Functions inherited from QCA::Algorithm
	Algorithm (const Algorithm &from)
void	change (const QString &type, const QString &provider)
void	change (Provider::Context *c)
Provider::Context *	context ()
const Provider::Context *	context () const
Algorithm &	operator= (const Algorithm &from)
Provider *	provider () const
Provider::Context *	takeContext ()
QString	type () const
Public Member Functions inherited from QCA::BufferedComputation
MemoryRegion	process (const MemoryRegion &a)

Static Public Member Functions
static QStringList	supportedTypes (const QString &provider=QString())

Additional Inherited Members
Protected Member Functions inherited from QCA::Algorithm
	Algorithm ()
	Algorithm (const QString &type, const QString &provider)

Detailed Description

General class for message authentication code (MAC) algorithms.

MessageAuthenticationCode is a class for accessing the various message authentication code algorithms within QCA. HMAC using SHA1 ("hmac(sha1)") or HMAC using SHA256 ("hmac(sha256)") is recommended for new applications.

Note that if your application is potentially susceptable to "replay attacks" where the message is sent more than once, you should include a counter in the message that is covered by the MAC, and check that the counter is always incremented every time you receive a message and MAC.

For more information on HMAC, see H. Krawczyk et al. RFC2104 "HMAC: Keyed-Hashing for Message Authentication"

Examples

aes-cmac.cpp, and mactest.cpp.

Constructor & Destructor Documentation

MessageAuthenticationCode() [1/2]

QCA::MessageAuthenticationCode::MessageAuthenticationCode	(	const QString &	type,
		const SymmetricKey &	key,
		const QString &	provider = QString() )

Standard constructor.

Parameters

type	the name of the MAC (and algorithm, if applicable) to use
key	the shared key
provider	the provider to use, if a particular provider is required

References QCA::Algorithm::provider(), and type().

Referenced by MessageAuthenticationCode(), and operator=().

MessageAuthenticationCode() [2/2]

QCA::MessageAuthenticationCode::MessageAuthenticationCode

(

const MessageAuthenticationCode &

from

)

Standard copy constructor.

Copies the state (including key) from one MessageAuthenticationCode to another

Parameters

from	the MessageAuthenticationCode to copy state from

References MessageAuthenticationCode().

Member Function Documentation

operator=()

MessageAuthenticationCode & QCA::MessageAuthenticationCode::operator=

(

const MessageAuthenticationCode &

from

)

Assignment operator.

Copies the state (including key) from one MessageAuthenticationCode to another

Parameters

from	the MessageAuthenticationCode to assign from.

References MessageAuthenticationCode().

supportedTypes()

QStringList QCA::MessageAuthenticationCode::supportedTypes ( const QString & provider = QString() )

static

Returns a list of all of the message authentication code types available.

Parameters

provider

the name of the provider to get a list from, if one provider is required. If not specified, available message authentication codes types from all providers will be returned.

References QCA::Algorithm::provider().

type()

QString QCA::MessageAuthenticationCode::type

(

)

const

Return the MAC type.

Referenced by MessageAuthenticationCode().

keyLength()

KeyLength QCA::MessageAuthenticationCode::keyLength

(

)

const

Return acceptable key lengths.

validKeyLength()

bool QCA::MessageAuthenticationCode::validKeyLength

(

int

n

)

const

Test if a key length is valid for the MAC algorithm.

Parameters

n	the key length in bytes

Returns

true if the key would be valid for the current algorithm

clear()

void QCA::MessageAuthenticationCode::clear ( )

overridevirtual

Reset a MessageAuthenticationCode, dumping all previous parts of the message.

This method clears (or resets) the algorithm, effectively undoing any previous update() calls. You should use this call if you are re-using a MessageAuthenticationCode sub-class object to calculate additional MACs. Note that if the key doesn't need to be changed, you don't need to call setup() again, since the key can just be reused.

Implements QCA::BufferedComputation.

update()

void QCA::MessageAuthenticationCode::update ( const MemoryRegion & array )

overridevirtual

Update the MAC, adding more of the message contents to the digest.

The whole message needs to be added using this method before you call final().

Parameters

array

the message contents

Implements QCA::BufferedComputation.

Examples

mactest.cpp.

final()

MemoryRegion QCA::MessageAuthenticationCode::final ( )

overridevirtual

Finalises input and returns the MAC result.

After calling update() with the required data, the hash results are finalised and produced.

Note that it is not possible to add further data (with update()) after calling final(). If you want to reuse the MessageAuthenticationCode object, you should call clear() and start to update() again.

Implements QCA::BufferedComputation.

Examples

mactest.cpp.

setup()

void QCA::MessageAuthenticationCode::setup

(

const SymmetricKey &

key

)

Initialise the MAC algorithm.

Parameters

key	the key to use for the algorithm

Examples

mactest.cpp.

---

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

• qca_basic.h