QCA::MessageAuthenticationCode Class Reference
[QCA user API]

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

#include <QtCrypto>

Inheritance diagram for QCA::MessageAuthenticationCode:

QCA::Algorithm QCA::BufferedComputation
Collaboration diagram for QCA::MessageAuthenticationCode:

Collaboration graph
[legend]

List of all members.

Public Member Functions

virtual void clear ()
virtual MemoryRegion final ()
KeyLength keyLength () const
 MessageAuthenticationCode (const MessageAuthenticationCode &from)
 MessageAuthenticationCode (const QString &type, const SymmetricKey &key, const QString &provider=QString())
MessageAuthenticationCodeoperator= (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())


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:

mactest.cpp.


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

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


Member Function Documentation

virtual 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.

virtual 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.

Examples:
mactest.cpp.

KeyLength QCA::MessageAuthenticationCode::keyLength (  )  const

Return acceptable key lengths.

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.

void QCA::MessageAuthenticationCode::setup ( const SymmetricKey key  ) 

Initialise the MAC algorithm.

Parameters:
key the key to use for the algorithm
Examples:
mactest.cpp.

static 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.

QString QCA::MessageAuthenticationCode::type (  )  const

Return the MAC type.

Reimplemented from QCA::Algorithm.

virtual 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.

Examples:
mactest.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


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

Generated on Wed Apr 29 15:16:05 2009 for Qt Cryptographic Architecture by  doxygen 1.5.5