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# SymmetricCipher Class Reference

`#include <cryptlib.h>`

Inheritance diagram for SymmetricCipher:

List of all members.

## Detailed Description

interface for stream ciphers

Definition at line 589 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
StreamTransformation & | Ref ()
| 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 Clonable * | Clone () 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 458 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 465 of file cryptlib.h.

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::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. Definition at line 76 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 MessageAuthenticationCodeFinalTemplate< BASE, INFO >, MessageAuthenticationCodeFinalTemplate< HMAC_Base, HMAC< T > >, MessageAuthenticationCodeFinalTemplate< XMACC_Base< T > >, MessageAuthenticationCodeFinalTemplate< DMAC_Base< T > >, MessageAuthenticationCodeFinalTemplate< CBC_MAC_Base, CBC_MAC< T > >, MessageAuthenticationCodeFinalTemplate< HMAC_Base, HMAC< DefaultHashModule > >, and MessageAuthenticationCodeFinalTemplate< 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 381 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 397 of file cryptlib.h.

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

- cryptlib.h