QCA::MessageAuthenticationCode Class Reference
[QCA user API]

General class for message authentication code (MAC) algorithms. More...

#include <QtCrypto>

Inheritance diagram for QCA::MessageAuthenticationCode:

[legend]

List of all members.

Public Member Functions
	MessageAuthenticationCode (const MessageAuthenticationCode &from)
	MessageAuthenticationCode (const QString &type, const SymmetricKey &key, const QString &provider=QString())
	~MessageAuthenticationCode ()
virtual void	clear ()
virtual MemoryRegion	final ()
KeyLength	keyLength () const
MessageAuthenticationCode &	operator= (const MessageAuthenticationCode &from)
void	setup (const SymmetricKey &key)
QString	type () const
virtual void	update (const MemoryRegion &array)
bool	validKeyLength (int n) const
Static Public Member Functions
static QStringList	supportedTypes (const QString &provider=QString())

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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"

Definition at line 768 of file qca_basic.h.

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Constructor & Destructor Documentation

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

Definition at line 436 of file qca_basic.cpp.

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

Definition at line 445 of file qca_basic.cpp.

QCA::MessageAuthenticationCode::~MessageAuthenticationCode

(

)

Definition at line 451 of file qca_basic.cpp.

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Member Function Documentation

void QCA::MessageAuthenticationCode::clear

(

)

[virtual]

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.

Definition at line 485 of file qca_basic.cpp.

MemoryRegion QCA::MessageAuthenticationCode::final

(

)

[virtual]

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.

Definition at line 498 of file qca_basic.cpp.

KeyLength QCA::MessageAuthenticationCode::keyLength

(

)

const

Return acceptable key lengths.

Definition at line 474 of file qca_basic.cpp.

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.

Reimplemented from QCA::Algorithm.

Definition at line 456 of file qca_basic.cpp.

void QCA::MessageAuthenticationCode::setup

(

const SymmetricKey &

key

)

Initialise the MAC algorithm.

Parameters:

key

the key to use for the algorithm

Definition at line 508 of file qca_basic.cpp.

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.

Definition at line 463 of file qca_basic.cpp.

QString QCA::MessageAuthenticationCode::type

(

)

const

Return the MAC type.

Reimplemented from QCA::Algorithm.

Definition at line 468 of file qca_basic.cpp.

void QCA::MessageAuthenticationCode::update

(

const MemoryRegion &

array

)

[virtual]

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.

Definition at line 491 of file qca_basic.cpp.

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

Definition at line 479 of file qca_basic.cpp.

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

• qca_basic.h
• qca_basic.cpp