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SymmetricCipher Class Reference

#include <cryptlib.h>

Inheritance diagram for SymmetricCipher:

StreamTransformation SimpleKeyingInterface Algorithm Clonable ARC4_Base MARC4_Base List of all members.

Detailed Description

interface for stream ciphers

Definition at line 572 of file cryptlib.h.

Public Types

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

Public Member Functions

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 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 bool IsRandomAccess () const=0
 returns whether this cipher supports random access

virtual void Seek (dword 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

virtual unsigned int MinKeyLength () const=0
 returns smallest valid key length in bytes */

virtual unsigned int MaxKeyLength () const=0
 returns largest valid key length in bytes */

virtual unsigned int DefaultKeyLength () const=0
 returns default (recommended) key length in bytes */

virtual unsigned int GetValidKeyLength (unsigned int n) const=0
 returns the smallest valid key length in bytes that is >= min(n, GetMaxKeyLength())

virtual bool IsValidKeyLength (unsigned int n) const
 returns whether n is a valid key length

virtual void SetKey (const byte *key, unsigned int length, const NameValuePairs &params=g_nullNameValuePairs)=0
 set or reset the key of this object

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"

virtual IV_Requirement IVRequirement () const=0
 returns the minimal requirement for secure IVs

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


Protected Member Functions

void ThrowIfInvalidKeyLength (const Algorithm &algorithm, unsigned int length)
void AssertValidKeyLength (unsigned int length) const


Member Function Documentation

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 441 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 448 of file cryptlib.h.

References StreamTransformation::MandatoryBlockSize().

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, and PublicBlumBlumShub.

Referenced by StreamTransformation::ProcessByte(), StreamTransformation::ProcessLastBlock(), and StreamTransformation::ProcessString().

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 73 of file cryptlib.cpp.

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

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

set or reset the key of this object

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

Implemented in MessageAuthenticationCodeTemplate< BASE >, MessageAuthenticationCodeTemplate< CBC_MAC_Base< T > >, MessageAuthenticationCodeTemplate< HMAC_Base< T > >, MessageAuthenticationCodeTemplate< XMACC_Base< T > >, MessageAuthenticationCodeTemplate< DMAC_Base< T > >, and MessageAuthenticationCodeTemplate< PanamaMAC_Base< B > >.

Referenced by SimpleKeyingInterface::SetKeyWithIV(), and SimpleKeyingInterface::SetKeyWithRounds().

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 364 of file cryptlib.h.

References SimpleKeyingInterface::IVRequirement().

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 380 of file cryptlib.h.


The documentation for this class was generated from the following file:
Generated on Mon Apr 19 18:12:47 2004 for Crypto++ by doxygen 1.3.6-20040222