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# CBC_Decryption Class Reference

Inheritance diagram for CBC_Decryption:

List of all members.

## Detailed Description

Definition at line 236 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
void | ProcessBlocks (byte *outString, const byte *inString, unsigned int numberOfBlocks)
IV_Requirement | IVRequirement () const
| returns the minimal requirement for secure IVs
bool | RequireAlignedInput () const
unsigned int | MinLastBlockSize () const
| returns the minimum size of the last block, 0 indicating the last block is not special
void | UncheckedSetKey (const NameValuePairs &params, const byte *key, unsigned int length, const byte *iv)
unsigned int | MandatoryBlockSize () const
| returns block size, if input must be processed in blocks, otherwise 1
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
void | Resynchronize (const byte *iv)
| resynchronize with an IV
void | ProcessData (byte *outString, const byte *inString, unsigned int length)
| encrypt or decrypt an array of bytes of specified length
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
void | GetNextIV (byte *IV)
| get a secure IV for the next message
StreamTransformation & | Ref ()
| return a reference to this object,
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 | 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
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 std::string | AlgorithmName () const
| returns name of this algorithm, not universally implemented yet
virtual Clonable * | Clone () 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)
## Static Public Member Functions
static const char *__cdecl | StaticAlgorithmName ()
## Protected Member Functions
void | ResizeBuffers ()
unsigned int | BlockSize () const
virtual void | SetFeedbackSize (unsigned int feedbackSize)
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
SecByteBlock | m_temp
SecByteBlock | m_buffer
BlockCipher * | m_cipher
SecByteBlock | m_register

## Member Function Documentation

void BlockOrientedCipherModeBase::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 113 of file modes.cpp. References BlockTransformation::BlockAlignment(), CipherModeBase::BlockSize(), BlockOrientedCipherModeBase::m_buffer, CipherModeBase::m_cipher, and BlockOrientedCipherModeBase::RequireAlignedInput().

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().

void CipherModeBase::GetNextIV | ( | byte * | IV | ) | `[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. Reimplemented from SimpleKeyingInterface. Reimplemented in CTR_ModePolicy. Definition at line 32 of file modes.cpp. References CipherModeBase::BlockSize(), StreamTransformation::IsForwardTransformation(), CipherModeBase::m_cipher, CipherModeBase::m_register, and BlockTransformation::ProcessBlock().

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().

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:

- modes.h
- modes.cpp