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MARC4 Class Reference

#include <arc4.h>

Inheritance diagram for MARC4:

SymmetricCipherFinal< MARC4_Base > AlgorithmImpl< SimpleKeyingInterfaceImpl< MARC4_Base, MARC4_Base >, MARC4_Base > SimpleKeyingInterfaceImpl< MARC4_Base, MARC4_Base > MARC4_Base ARC4_Base VariableKeyLength< 16, 1, 256 > RandomNumberGenerator SymmetricCipher SymmetricCipherDocumentation Algorithm StreamTransformation SimpleKeyingInterface Clonable Algorithm Clonable List of all members.

Detailed Description

Modified ARC4: it discards the first 256 bytes of keystream which may be weaker than the rest.

Definition at line 49 of file arc4.h.

Public Types

typedef SymmetricCipherFinal<
MARC4_Base
Encryption
 implements the SymmetricCipher interface
typedef SymmetricCipherFinal<
MARC4_Base
Decryption
 implements the SymmetricCipher interface
enum  IV_Requirement {
  STRUCTURED_IV = 0, RANDOM_IV, UNPREDICTABLE_RANDOM_IV, INTERNALLY_GENERATED_IV,
  NOT_RESYNCHRONIZABLE
}

Public Member Functions

void SetKey (const byte *key, unsigned int length, const NameValuePairs &params=g_nullNameValuePairs)
 set or reset the key of this object
ClonableClone () const
 this is not implemented by most classes yet
std::string AlgorithmName () const
 returns name of this algorithm, not universally implemented yet
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())
MARC4_Base::IV_Requirement IVRequirement () const
 returns the minimal requirement for secure IVs
byte GenerateByte ()
 generate new random byte and return it
void DiscardBytes (unsigned int n)
 generate and discard n bytes
void ProcessData (byte *outString, const byte *inString, unsigned int length)
 encrypt or decrypt an array of bytes of specified length
bool IsRandomAccess () const
 returns whether this cipher supports random access
bool IsSelfInverting () const
 returns whether this transformation is self-inverting (e.g. xor with a keystream)
bool IsForwardTransformation () const
 returns whether this is an encryption object
virtual unsigned int GenerateBit ()
 generate new random bit and return it
virtual word32 GenerateWord32 (word32 a=0, word32 b=0xffffffffL)
 generate a random 32 bit word in the range min to max, inclusive
virtual void GenerateBlock (byte *output, unsigned int size)
 generate random array of bytes
template<class IT> void Shuffle (IT begin, IT end)
 randomly shuffle the specified array, resulting permutation is uniformly distributed
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 unsigned int OptimalDataAlignment () const
 returns how input should be aligned for optimal performance
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 IsValidKeyLength (unsigned int n) const
 returns whether n is a valid key length
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 unsigned int IVSize () const
 returns size of IVs used by this object
virtual void Resynchronize (const byte *IV)
 resynchronize with an IV
virtual void GetNextIV (byte *IV)
 get a secure IV for the next message

Static Public Member Functions

std::string StaticAlgorithmName ()
unsigned int StaticGetValidKeyLength (unsigned int n)

Protected Member Functions

void AssertValidKeyLength (unsigned int length)
void AssertValidKeyLength (unsigned int length) const
unsigned int GetDefaultDiscardBytes () const
void UncheckedSetKey (const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
void ThrowIfInvalidKeyLength (const Algorithm &algorithm, unsigned int length)
void ThrowIfResynchronizable ()
void ThrowIfInvalidIV (const byte *iv)
const byte * GetIVAndThrowIfInvalid (const NameValuePairs &params)

Protected Attributes

FixedSizeSecBlock< byte, 256 > m_state
byte m_x
byte m_y


Member Function Documentation

void SymmetricCipherFinal< MARC4_Base , MARC4_Base >::SetKey const byte *  key,
unsigned int  length,
const NameValuePairs params = g_nullNameValuePairs
[inline, virtual, inherited]
 

Implements SimpleKeyingInterface.

Definition at line 277 of file strciphr.h.

void ARC4_Base::DiscardBytes unsigned int  n  )  [virtual, inherited]
 

generate and discard n bytes

Default implementation is to call GenerateByte() n times.

Reimplemented from RandomNumberGenerator.

Definition at line 97 of file arc4.cpp.

void ARC4_Base::ProcessData byte *  outString,
const byte *  inString,
unsigned int  length
[virtual, inherited]
 

encrypt or decrypt an array of bytes of specified length

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

Implements StreamTransformation.

Definition at line 68 of file arc4.cpp.

unsigned int RandomNumberGenerator::GenerateBit  )  [virtual, inherited]
 

generate new random bit and return it

Default implementation is to call GenerateByte() and return its parity.

Reimplemented in PublicBlumBlumShub.

Definition at line 111 of file cryptlib.cpp.

References RandomNumberGenerator::GenerateByte().

void RandomNumberGenerator::GenerateBlock byte *  output,
unsigned int  size
[virtual, inherited]
 

generate random array of bytes

Default implementation is to call GenerateByte() size times.

Reimplemented in NonblockingRng, BlockingRng, and RandomPool.

Definition at line 116 of file cryptlib.cpp.

References RandomNumberGenerator::GenerateByte().

Referenced by DL_GroupParameters_DSA::GenerateRandom().

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
Definition at line 471 of file cryptlib.h.

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. Definition at line 101 of file cryptlib.cpp.

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

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.

virtual void SimpleKeyingInterface::GetNextIV byte *  IV  )  [inline, virtual, inherited]
 

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. Definition at line 400 of file cryptlib.h.


The documentation for this class was generated from the following file:
Generated on Wed Jul 21 19:15:57 2004 for Crypto++ by doxygen 1.3.7-20040704