CTR_ModePolicy Class Reference

Inheritance diagram for CTR_ModePolicy:

ModePolicyCommonTemplate< AdditiveCipherAbstractPolicy > CipherModeBase AdditiveCipherAbstractPolicy SymmetricCipher StreamTransformation SimpleKeyingInterface Algorithm Clonable List of all members.

Detailed Description

Definition at line 147 of file modes.h.

Public Types

enum  IV_Requirement {
  STRUCTURED_IV = 0, RANDOM_IV, UNPREDICTABLE_RANDOM_IV, INTERNALLY_GENERATED_IV,
  NOT_RESYNCHRONIZABLE
}

Public Member Functions

bool IsRandomAccess () const
IV_Requirement IVRequirement () const
 returns the minimal requirement for secure IVs
void GetNextIV (byte *IV)
 get a secure IV for the next message
unsigned int MinKeyLength () const
 returns smallest valid key length in bytes */
unsigned int MaxKeyLength () const
 returns largest valid key length in bytes */
unsigned int DefaultKeyLength () const
 returns default (recommended) key length in bytes */
unsigned int GetValidKeyLength (unsigned int n) const
 returns the smallest valid key length in bytes that is >= min(n, GetMaxKeyLength())
bool IsValidKeyLength (unsigned int n) const
 returns whether n is a valid key length
void SetKey (const byte *key, unsigned int length, const NameValuePairs &params=g_nullNameValuePairs)
 set or reset the key of this object
unsigned int OptimalDataAlignment () const
 returns how input should be aligned for optimal performance
unsigned int IVSize () const
 returns size of IVs used by this object
StreamTransformationRef ()
 return a reference to this object,
virtual unsigned int MandatoryBlockSize () const
 returns block size, if input must be processed in blocks, otherwise 1
virtual unsigned int OptimalBlockSize () const
 returns the input block size that is most efficient for this cipher
virtual unsigned int GetOptimalBlockSizeUsed () const
 returns how much of the current block is used up
virtual void ProcessData (byte *outString, const byte *inString, unsigned int length)=0
 encrypt or decrypt an array of bytes of specified length
virtual void ProcessLastBlock (byte *outString, const byte *inString, unsigned int length)
 for ciphers where the last block of data is special, encrypt or decrypt the last block of data
virtual unsigned int MinLastBlockSize () const
 returns the minimum size of the last block, 0 indicating the last block is not special
void ProcessString (byte *inoutString, unsigned int length)
 same as ProcessData(inoutString, inoutString, length)
void ProcessString (byte *outString, const byte *inString, unsigned int length)
 same as ProcessData(outString, inString, length)
byte ProcessByte (byte input)
 implemented as {ProcessData(&input, &input, 1); return input;}
virtual void Seek (lword n)
 for random access ciphers, seek to an absolute position
virtual bool IsSelfInverting () const =0
 returns whether this transformation is self-inverting (e.g. xor with a keystream)
virtual bool IsForwardTransformation () const =0
 returns whether this is an encryption object
virtual std::string AlgorithmName () const
 returns name of this algorithm, not universally implemented yet
virtual ClonableClone () const
 this is not implemented by most classes yet
void SetKeyWithRounds (const byte *key, unsigned int length, int rounds)
 calls SetKey() with an NameValuePairs object that just specifies "Rounds"
void SetKeyWithIV (const byte *key, unsigned int length, const byte *iv)
 calls SetKey() with an NameValuePairs object that just specifies "IV"
bool IsResynchronizable () const
 returns whether this object can be resynchronized (i.e. supports initialization vectors)
bool CanUseRandomIVs () const
 returns whether this object can use random IVs (in addition to ones returned by GetNextIV)
bool CanUsePredictableIVs () const
 returns whether this object can use random but possibly predictable IVs (in addition to ones returned by GetNextIV)
bool CanUseStructuredIVs () const
 returns whether this object can use structured IVs, for example a counter (in addition to ones returned by GetNextIV)
virtual void Resynchronize (const byte *IV)
 resynchronize with an IV

Static Public Member Functions

static const char * StaticAlgorithmName ()

Protected Member Functions

unsigned int BlockSize () const
virtual void SetFeedbackSize (unsigned int feedbackSize)
virtual void ResizeBuffers ()
virtual void UncheckedSetKey (const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)=0
void ThrowIfInvalidKeyLength (const Algorithm &algorithm, unsigned int length)
void ThrowIfResynchronizable ()
void ThrowIfInvalidIV (const byte *iv)
const byte * GetIVAndThrowIfInvalid (const NameValuePairs &params)
void AssertValidKeyLength (unsigned int length) const

Protected Attributes

BlockCipherm_cipher
SecByteBlock m_register


Member Function Documentation

void CTR_ModePolicy::GetNextIV byte *  IV  )  [virtual]
 

get a secure IV for the next message

This method should be called after you finish encrypting one message and are ready to start the next one. After calling it, you must call SetKey() or Resynchronize() before using this object again. This method is not implemented on decryption objects.

Reimplemented from CipherModeBase.

Definition at line 67 of file modes.cpp.

References CipherModeBase::BlockSize().

void CipherModeBase::SetKey const byte *  key,
unsigned int  length,
const NameValuePairs params = g_nullNameValuePairs
[virtual, inherited]
 

set or reset the key of this object

Parameters:
params is used to specify Rounds, BlockSize, etc

Implements SimpleKeyingInterface.

Definition at line 27 of file modes.cpp.

References SimpleKeyingInterface::GetIVAndThrowIfInvalid().

StreamTransformation& StreamTransformation::Ref  )  [inline, inherited]
 

return a reference to this object,

This function is useful for passing a temporary StreamTransformation object to a function that takes a non-const reference.

Definition at line 464 of file cryptlib.h.

virtual unsigned int StreamTransformation::OptimalBlockSize  )  const [inline, virtual, inherited]
 

returns the input block size that is most efficient for this cipher

Note:
optimal input length is n * OptimalBlockSize() - GetOptimalBlockSizeUsed() for any n > 0

Reimplemented in ECB_OneWay.

Definition at line 471 of file cryptlib.h.

Referenced by StreamTransformationFilter::FirstPut().

virtual void StreamTransformation::ProcessData byte *  outString,
const byte *  inString,
unsigned int  length
[pure virtual, inherited]
 

encrypt or decrypt an array of bytes of specified length

Note:
either inString == outString, or they don't overlap

Implemented in ARC4_Base, PublicBlumBlumShub, and BlockOrientedCipherModeBase.

Referenced by StreamTransformationFilter::LastPut(), and StreamTransformation::ProcessLastBlock().

void StreamTransformation::ProcessLastBlock byte *  outString,
const byte *  inString,
unsigned int  length
[virtual, inherited]
 

for ciphers where the last block of data is special, encrypt or decrypt the last block of data

For now the only use of this function is for CBC-CTS mode.

Reimplemented in CBC_CTS_Encryption, and CBC_CTS_Decryption.

Definition at line 101 of file cryptlib.cpp.

References StreamTransformation::MandatoryBlockSize(), StreamTransformation::MinLastBlockSize(), and StreamTransformation::ProcessData().

Referenced by StreamTransformationFilter::LastPut().

bool SimpleKeyingInterface::IsResynchronizable  )  const [inline, inherited]
 

returns whether this object can be resynchronized (i.e. supports initialization vectors)

If this function returns true, and no IV is passed to SetKey() and CanUseStructuredIVs()==true, an IV of all 0's will be assumed.

Definition at line 384 of file cryptlib.h.

Referenced by SimpleKeyingInterface::ThrowIfInvalidIV(), SimpleKeyingInterface::ThrowIfResynchronizable(), and BlockOrientedCipherModeBase::UncheckedSetKey().


The documentation for this class was generated from the following files:
Generated on Fri Dec 16 03:04:21 2005 for Crypto++ by  doxygen 1.4.5