Crypto++ 8.9
Free C++ class library of cryptographic schemes
Public Member Functions | Static Public Member Functions | List of all members
CBC_ModeBase Class Reference

CBC block cipher mode of operation default implementation. More...

#include <modes.h>

+ Inheritance diagram for CBC_ModeBase:

Public Member Functions

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
StreamTransformationRef ()
 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 void ProcessData (byte *outString, const byte *inString, size_t length)=0
 Encrypt or decrypt an array of bytes.
 
virtual size_t ProcessLastBlock (byte *outString, size_t outLength, const byte *inString, size_t inLength)
 Encrypt or decrypt the last block of data.
 
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 ClonableClone () const
 Copies this object.
 

Static Public Member Functions

static const char * StaticAlgorithmName ()
 

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...
 

Detailed Description

CBC block cipher mode of operation default implementation.

Definition at line 284 of file modes.h.

Member Function Documentation

◆ StaticAlgorithmName()

static const char * CBC_ModeBase::StaticAlgorithmName ( )
inlinestatic

Definition at line 287 of file modes.h.

◆ IVRequirement()

IV_Requirement CBC_ModeBase::IVRequirement ( ) const
inlinevirtual

Minimal requirement for secure IVs.

Returns
the secure IV requirement of the algorithm

Implements CipherModeBase.

Definition at line 289 of file modes.h.

◆ RequireAlignedInput()

bool CBC_ModeBase::RequireAlignedInput ( ) const
inline

Definition at line 290 of file modes.h.

◆ MinLastBlockSize()

unsigned int CBC_ModeBase::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 291 of file modes.h.


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