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conn::CSecureBUREncryptKeySource Class Reference

class conn::CSecureBUREncryptKeySource : public CBase

This class is responsible for providing keys for encryption of backup data or decryption of restore data based on drive and SID of the data owner.

The class will be included in a separate key-providing DLL provided by licensees at build time. The default Symbian implementation will not provide keys.

It is permissible to not provide any keys and to not encrypt data. It is also permissible for one key to be common to all or a set of SIDs or for one key to be common to a set of drives.

The class can provide a data buffer with backup keys. If it does then the buffer will be stored (un-encrypted!) with the backup and will be provided when keys are requested for a restore operation. The class supports a default data buffer for a whole backup plus the ability to override it with buffers for specific SIDs. If the buffer is used then the implementor must be aware that is is not encrypted in the backup and so must not contain any sensitive data or any data that would allow an attacker to recreate the key. If a buffer is provided then it is returned at restore time on a per-SID basis - there is no provision to provide a default buffer at restore time.

If keys are provided then the implementor needs to consider a number of factors:

If the key is entered by the user then it should be assumed that the user can decrypt data off the device.

If the key is local to the device then the data cannot be restored to a new device.

If the key depends on the drive being backed up or restored then the implementor needs to consider whether a drive may have its letter changed (e.g. if a device has multiple slots for removable media).

This class owns a CSecureBURKeySourceImpl instance and publishes the public API to the outside world. The reason for this facade class is twofold:

Hiding the implementation details of CSecureBURKeySourceImpl

Future binary compatibility

Inherits from

conn::CSecureBUREncryptKeySource
- CBase

Public Member Functions
	~CSecureBUREncryptKeySource ()
IMPORT_C void	GetBackupKeyL ( TDriveNumber , TSecureId , TBool &, TDes8 &, TBool &, TDes &)
IMPORT_C void	GetDefaultBufferForBackupL ( TDriveNumber , TBool &, TDes &)
IMPORT_C void	GetRestoreKeyL ( TDriveNumber , TSecureId , TBool , TDes &, TBool &, TDes8 &)
IMPORT_C CSecureBUREncryptKeySource *	NewL ()

Private Member Functions
	CSecureBUREncryptKeySource ()
void	ConstructL ()

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()

Private Attributes
CSecureBURKeySourceImpl *	iImpl

Constructor & Destructor Documentation

CSecureBUREncryptKeySource()

CSecureBUREncryptKeySource

(

)

[private]

Standard C++ Constructor

C++ constructor

~CSecureBUREncryptKeySource()

IMPORT_C

~CSecureBUREncryptKeySource

(

)

[virtual]

Standard virtual destructor

Member Functions Documentation

ConstructL()

void

ConstructL

(

)

[private]

Symbian Second phase constructor

Symbian 2nd phase construction

GetBackupKeyL(TDriveNumber, TSecureId, TBool &, TDes8 &, TBool &, TDes &)

IMPORT_C void	GetBackupKeyL	(	TDriveNumber	aDrive,
			TSecureId	aSID,
			TBool &	aDoEncrypt,
			TDes8 &	aKey,
			TBool &	aGotBuffer,
			TDes &	aBuffer
		)

Provides a key to use to encrypt backup data for a specific data owner from a specific drive. It is permissible to provide the same key for some or all data owners. It is permissible to provide the same key for some or all drives.

Parameters

TDriveNumber aDrive	the drive (EDrive A to EDriveZ) which is being backed up
TSecureId aSID	the secure id of the data owner
TBool & aDoEncrypt	returns ETrue if a key is provided, EFalse if data is not to be encrypted
TDes8 & aKey	the key to use to encrypt data - ignored if aDoEncrypt is set to EFalse
TBool & aGotBuffer	returns ETrue if a buffer is returned that is specific to this SID
TDes & aBuffer	if aGotBuffer is set to ETrue then this is a buffer of data to be included with backups.

GetDefaultBufferForBackupL(TDriveNumber, TBool &, TDes &)

IMPORT_C void	GetDefaultBufferForBackupL	(	TDriveNumber	aDrive,
			TBool &	aGotBuffer,
			TDes &	aBuffer
		)

Get a default data buffer for all backups of a specified drive.

Parameters

TDriveNumber aDrive	the drive being backed up - may be ignored
TBool & aGotBuffer	set to ETrue on return if a buffer is supplied
TDes & aBuffer	if aGotBuffer is set to ETrue then this is a buffer of data to be included with backups.

GetRestoreKeyL(TDriveNumber, TSecureId, TBool, TDes &, TBool &, TDes8 &)

IMPORT_C void	GetRestoreKeyL	(	TDriveNumber	aDrive,
			TSecureId	aSID,
			TBool	aGotBuffer,
			TDes &	aBuffer,
			TBool &	aGotKey,
			TDes8 &	aKey
		)

Provides a key to use to decrypt backup data for a specific data owner from a specific drive. It is permissible to provide the same key for some or all data owners. It is permissible to provide the same key for some or all drives.

Parameters

TDriveNumber aDrive	the drive (EDrive A to EDriveZ) which is being restored
TSecureId aSID	the secure id of the data owner
TBool aGotBuffer	set to ETrue if a buffer is provided
TDes & aBuffer	if aGotBuffer is set to ETrue then this is a buffer of data that was provided with the key for the backup (or the default buffer)
TBool & aGotKey	returns ETrue if a key is provided, EFalse if data is not to be decrypted
TDes8 & aKey	the key to use to decrypt data - ignored if aGotKey is set to EFalse

NewL()

IMPORT_C CSecureBUREncryptKeySource *

NewL

(

)

[static]

Static factory method (two phase construction)

Member Data Documentation

CSecureBURKeySourceImpl * iImpl

CSecureBURKeySourceImpl *

iImpl

[private]

Pointer the the CSecureBURKeySourceImpl implementation