CBC-CTS block cipher mode of operation decryption operation. More...

#include <modes.h>

Inheritance diagram for CBC_CTS_Decryption:

Public Member Functions
unsigned int	MinLastBlockSize () const
	Provides the size of the last block.

size_t	ProcessLastBlock (byte outString, size_t outLength, const byte inString, size_t inLength)
	Encrypt or decrypt the last block of data.

Public Member Functions inherited from CBC_Decryption
void	ProcessData (byte outString, const byte inString, size_t length)
	Encrypt or decrypt an array of bytes.

Public Member Functions inherited from CBC_ModeBase
CRYPTOPP_STATIC_CONSTEXPR const char *CRYPTOPP_API	StaticAlgorithmName ()

IV_Requirement	IVRequirement () const
	Minimal requirement for secure IVs.

bool	RequireAlignedInput () const

unsigned int	MinLastBlockSize () const
	Provides the size of the last block.

Public Member Functions inherited from BlockOrientedCipherModeBase
void	UncheckedSetKey (const byte *key, unsigned int length, const NameValuePairs &params)
	Sets the key for this object without performing parameter validation.

unsigned int	MandatoryBlockSize () const
	Provides the mandatory block size of the cipher.

bool	IsRandomAccess () const
	Determines whether the cipher supports random access.

bool	IsSelfInverting () const
	Determines whether the cipher is self-inverting.

bool	IsForwardTransformation () const
	Determines if the cipher is being operated in its forward direction.

void	Resynchronize (const byte *iv, int length=-1)
	Resynchronize with an IV.

Public Member Functions inherited from CipherModeBase
std::string	AlgorithmProvider () const
	Retrieve the provider of this algorithm.

size_t	MinKeyLength () const
	Returns smallest valid key length.

size_t	MaxKeyLength () const
	Returns largest valid key length.

size_t	DefaultKeyLength () const
	Returns default key length.

size_t	GetValidKeyLength (size_t keylength) const
	Returns a valid key length for the algorithm.

bool	IsValidKeyLength (size_t keylength) const
	Returns whether keylength is a valid key length.

unsigned int	OptimalDataAlignment () const
	Provides input and output data alignment for optimal performance.

unsigned int	IVSize () const
	Returns length of the IV accepted by this object.

void	SetCipher (BlockCipher &cipher)
	Set external block cipher.

void	SetCipherWithIV (BlockCipher &cipher, const byte *iv, int feedbackSize=0)
	Set external block cipher and IV.

Public Member Functions inherited from SimpleKeyingInterface
virtual void	SetKey (const byte *key, size_t length, const NameValuePairs &params=g_nullNameValuePairs)
	Sets or reset the key of this object.

void	SetKeyWithRounds (const byte *key, size_t length, int rounds)
	Sets or reset the key of this object.

void	SetKeyWithIV (const byte key, size_t length, const byte iv, size_t ivLength)
	Sets or reset the key of this object.

void	SetKeyWithIV (const byte key, size_t length, const byte iv)
	Sets or reset the key of this object.

bool	IsResynchronizable () const
	Determines if the object can be resynchronized.

bool	CanUseRandomIVs () const
	Determines if the object can use random IVs.

bool	CanUsePredictableIVs () const
	Determines if the object can use random but possibly predictable IVs.

bool	CanUseStructuredIVs () const
	Determines if the object can use structured IVs.

unsigned int	DefaultIVLength () const
	Provides the default size of an IV.

virtual unsigned int	MinIVLength () const
	Provides the minimum size of an IV.

virtual unsigned int	MaxIVLength () const
	Provides the maximum size of an IV.

virtual void	GetNextIV (RandomNumberGenerator &rng, byte *iv)
	Retrieves a secure IV for the next message.

Public Member Functions inherited from StreamTransformation
StreamTransformation &	Ref ()
	Provides a reference to this object.

virtual unsigned int	OptimalBlockSize () const
	Provides the input block size most efficient for this cipher.

virtual unsigned int	GetOptimalBlockSizeUsed () const
	Provides the number of bytes used in the current block when processing at optimal block size.

virtual bool	IsLastBlockSpecial () const
	Determines if the last block receives special processing.

void	ProcessString (byte *inoutString, size_t length)
	Encrypt or decrypt a string of bytes.

void	ProcessString (byte outString, const byte inString, size_t length)
	Encrypt or decrypt a string of bytes.

byte	ProcessByte (byte input)
	Encrypt or decrypt a byte.

virtual void	Seek (lword pos)
	Seek to an absolute position.

Public Member Functions inherited from Algorithm
	Algorithm (bool checkSelfTestStatus=true)
	Interface for all crypto algorithms.

virtual std::string	AlgorithmName () const
	Provides the name of this algorithm.

Public Member Functions inherited from Clonable
virtual Clonable *	Clone () const
	Copies this object.

Additional Inherited Members
Public Types inherited from SimpleKeyingInterface
enum	IV_Requirement { UNIQUE_IV = 0 , RANDOM_IV , UNPREDICTABLE_RANDOM_IV , INTERNALLY_GENERATED_IV , NOT_RESYNCHRONIZABLE }
	Secure IVs requirements as enumerated values. More...

Protected Member Functions inherited from CBC_Decryption
virtual void	ResizeBuffers ()

Protected Member Functions inherited from BlockOrientedCipherModeBase
bool	RequireAlignedInput () const

Protected Member Functions inherited from CipherModeBase
unsigned int	BlockSize () const

virtual void	SetFeedbackSize (unsigned int feedbackSize)

Protected Member Functions inherited from SymmetricCipher
const Algorithm &	GetAlgorithm () const
	Returns the base class Algorithm.

Protected Member Functions inherited from SimpleKeyingInterface
void	ThrowIfInvalidKeyLength (size_t length)
	Validates the key length.

void	ThrowIfResynchronizable ()
	Validates the object.

void	ThrowIfInvalidIV (const byte *iv)
	Validates the IV.

size_t	ThrowIfInvalidIVLength (int length)
	Validates the IV length.

const byte *	GetIVAndThrowIfInvalid (const NameValuePairs &params, size_t &size)
	Retrieves and validates the IV.

void	AssertValidKeyLength (size_t length) const
	Validates the key length.

Protected Attributes inherited from CBC_Decryption
SecByteBlock	m_temp

Protected Attributes inherited from BlockOrientedCipherModeBase
SecByteBlock	m_buffer

Protected Attributes inherited from CipherModeBase
BlockCipher *	m_cipher

SecByteBlock	m_register

Detailed Description

CBC-CTS block cipher mode of operation decryption operation.

Since: Crypto++ 3.0

Definition at line 337 of file modes.h.

Member Function Documentation

◆ MinLastBlockSize()

unsigned int CBC_CTS_Decryption::MinLastBlockSize ( ) const

inlinevirtual

Provides the size of the last block.

Returns: the minimum size of the last block

MinLastBlockSize() returns the minimum size of the last block. 0 indicates the last block is not special.

MandatoryBlockSize() enlists one of two behaviors. First, if MandatoryBlockSize() returns 1, then the cipher can be streamed and ProcessData() is called with the tail bytes. Second, if MandatoryBlockSize() returns non-0, then the string of bytes is padded to MandatoryBlockSize() according to the padding mode. Then, ProcessData() is called with the padded string of bytes.

Some authenticated encryption modes are not expressed well with MandatoryBlockSize() and MinLastBlockSize(). For example, AES/OCB uses 16-byte blocks (MandatoryBlockSize = 16) and the last block requires special processing (MinLastBlockSize = 0). However, 0 is a valid last block size for OCB and the special processing is custom padding, and not standard PKCS padding. In response an unambiguous IsLastBlockSpecial() was added.

See also: ProcessData, ProcessLastBlock, MandatoryBlockSize, MinLastBlockSize, BlockPaddingSchemeDef, IsLastBlockSpecial

Reimplemented from StreamTransformation.

Definition at line 340 of file modes.h.

◆ ProcessLastBlock()

size_t CBC_CTS_Decryption::ProcessLastBlock	(	byte *	outString,
		size_t	outLength,
		const byte *	inString,
		size_t	inLength
	)

virtual

Encrypt or decrypt the last block of data.

Parameters

outString	the output byte buffer
outLength	the size of the output byte buffer, in bytes
inString	the input byte buffer
inLength	the size of the input byte buffer, in bytes

Returns: the number of bytes used in outString

ProcessLastBlock is used when the last block of data is special and requires handling by the cipher. The current implementation provides an output buffer with a size inLength+2*MandatoryBlockSize(). The return value allows the cipher to expand cipher text during encryption or shrink plain text during decryption.

This member function is used by CBC-CTS and OCB modes.

See also: ProcessData, ProcessLastBlock, MandatoryBlockSize, MinLastBlockSize, BlockPaddingSchemeDef, IsLastBlockSpecial

Reimplemented from StreamTransformation.

Definition at line 263 of file modes.cpp.

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

G:/work/subversion/scol-technologies/trunk/scol/plugins/security/cryptopp/modes.h
G:/work/subversion/scol-technologies/trunk/scol/plugins/security/cryptopp/modes.cpp

Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ MinLastBlockSize()

◆ ProcessLastBlock()