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CPadding Class Reference

class CPadding : public CBase

Abstract base class defining the interface to padding schemes.

It is designed to be used by both symmetric and asymmetric ciphers.

Inherits from

Public Member Functions
IMPORT_C TInt BlockSize (void)
TInt GetExtension ( TUint , TAny *&, TAny *)
IMPORT_C TInt MaxPaddedLength ( TInt )
IMPORT_C TInt MaxUnPaddedLength ( TInt )
TInt MinPaddingLength (void)
IMPORT_C void PadL (const TDesC8 &, TDes8 &)
IMPORT_C void SetBlockSize ( TInt )
void UnPadL (const TDesC8 &, TDes8 &)
Protected Member Functions
CPadding ( TInt )
Private Member Functions
CPadding (void)
CPadding (const CPadding &)
void DoPadL (const TDesC8 &, TDes8 &)
CPadding & operator= (const CPadding &)
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
TInt iBlockBytes

Constructor & Destructor Documentation

CPadding(TInt)

IMPORT_C CPadding ( TInt aBlockBytes ) [protected]

Constructor

Parameters

TInt aBlockBytes The block size in bytes.

CPadding(void)

CPadding ( void ) [private]

Parameters

void

CPadding(const CPadding &)

CPadding ( const CPadding & ) [private]

Parameters

const CPadding &

Member Functions Documentation

BlockSize(void)

IMPORT_C TInt BlockSize ( void ) const

Retrieves the block size for this padding system.

Parameters

void

DoPadL(const TDesC8 &, TDes8 &)

void DoPadL ( const TDesC8 & aInput,
TDes8 & aOutput
) [private, pure virtual]

Parameters

const TDesC8 & aInput
TDes8 & aOutput

GetExtension(TUint, TAny *&, TAny *)

TInt GetExtension ( TUint aExtensionId,
TAny *& a0,
TAny * a1
)

Used to retrieve the extended interfaces by id. For Crypto SPI internal use only.

Parameters

TUint aExtensionId
TAny *& a0
TAny * a1

MaxPaddedLength(TInt)

IMPORT_C TInt MaxPaddedLength ( TInt aInputBytes ) const [virtual]

Gets the size of the aOutput buffer, in a call to PadL() , must be in order to accommodate a block size of BlockSize() and an input size of aInputBytes.

Note:

By default, this function returns the output of BlockSize() . If a derived padding system outputs more than a single block of padding, one must override this function and return the appropriate value.

Parameters

TInt aInputBytes The amount of data to be padded out in bytes.

MaxUnPaddedLength(TInt)

IMPORT_C TInt MaxUnPaddedLength ( TInt aInputBytes ) const [virtual]

Gets the size of the aOutput buffer, in a call to UnPadL() , must be in order to accommodate an input size of aInputBytes.

Note:

By default, this function returns the value of aInputBytes minus MinPaddingBytes(). Most padding systems cannot determine anything about the unpadded length without looking at the data. If your padding system allows you to give a better bound, then you should reimplement this function.

Parameters

TInt aInputBytes The amount of data to be unpadded in bytes.

MinPaddingLength(void)

TInt MinPaddingLength ( void ) const [pure virtual]

Gets the smallest number of bytes that PadL() will ever add to aInput in order to get a valid block aligned aOutput.

For example, in SSLv3 padding, if the block size is 8 and aInput is 7 bytes, it will append 1 byte of padding. For SSLv3 padding, this is the smallest amount possible as an 8 byte input will add another block size (8 more bytes) of padded data.

Parameters

void

PadL(const TDesC8 &, TDes8 &)

IMPORT_C void PadL ( const TDesC8 & aInput,
TDes8 & aOutput
)

Pads aInput to be BlockSize() bytes long and places the result in aOutput.

Parameters

const TDesC8 & aInput Data to be padded. The size must be less than or equal to BlockSize() minus MinPaddingLength().
TDes8 & aOutput On return, the resulting padded, block size aligned data appended to aOutput.

SetBlockSize(TInt)

IMPORT_C void SetBlockSize ( TInt aBlockBytes )

Sets the block size for this padding system.

Parameters

TInt aBlockBytes The block size in bytes.

UnPadL(const TDesC8 &, TDes8 &)

void UnPadL ( const TDesC8 & aInput,
TDes8 & aOutput
) [pure virtual]

Removes padding from aInput and appends unpadded result to aOutput.

Parameters

const TDesC8 & aInput Data to be unpadded.
TDes8 & aOutput On return, the unpadded data.

operator=(const CPadding &)

CPadding & operator= ( const CPadding & ) [private]

Parameters

const CPadding &

Member Data Documentation

TInt iBlockBytes

TInt iBlockBytes [private]

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