Crypto++ 8.5 Free C++ class library of cryptographic schemes

Public Member Functions | Static Public Member Functions | List of all members
XTS_ModeBase Class Referenceabstract

XTS block cipher mode of operation default implementation. More...

Inheritance diagram for XTS_ModeBase:

## Public Member Functions
std::string | AlgorithmName () const
| Provides the name of this algorithm. More...
std::string | AlgorithmProvider () const
| Retrieve the provider of this algorithm. More...
size_t | MinKeyLength () const
| Returns smallest valid key length. More...
size_t | MaxKeyLength () const
| Returns largest valid key length. More...
size_t | DefaultKeyLength () const
| Returns default key length. More...
size_t | GetValidKeyLength (size_t n) const
| Returns a valid key length for the algorithm. More...
bool | IsValidKeyLength (size_t keylength) const
| Returns whether keylength is a valid key length. More...
void | ThrowIfInvalidKeyLength (size_t length)
| Validates the key length. More...
unsigned int | BlockSize () const
| Provides the block size of the cipher. More...
unsigned int | GetOptimalBlockSize () const
| Provides the input block size most efficient for this cipher. More...
unsigned int | MinLastBlockSize () const
| Provides the size of the last block. More...
unsigned int | OptimalDataAlignment () const
| Provides input and output data alignment for optimal performance. More...
void | ThrowIfInvalidBlockSize (size_t length)
| Validates the block size. More...
void | SetKey (const byte *key, size_t length, const NameValuePairs &params=g_nullNameValuePairs)
| Sets or reset the key of this object. More...
IV_Requirement | IVRequirement () const
| Minimal requirement for secure IVs. More...
void | Resynchronize (const byte *iv, int ivLength=-1)
| Resynchronize with an IV. More...
void | ProcessData (byte *outString, const byte *inString, size_t length)
| Encrypt or decrypt an array of bytes. More...
size_t | ProcessLastBlock (byte *outString, size_t outLength, const byte *inString, size_t inLength)
| Encrypt or decrypt the last block of data. More...
void | Resynchronize (word64 sector, ByteOrder order=BIG_ENDIAN_ORDER)
| Resynchronize the cipher. More...
Public Member Functions inherited from BlockOrientedCipherModeBase
void | UncheckedSetKey (const byte *key, unsigned int length, const NameValuePairs &params)
| Sets the key for this object without performing parameter validation. More...
unsigned int | MandatoryBlockSize () const
| Provides the mandatory block size of the cipher. More...
bool | IsRandomAccess () const
| Determines whether the cipher supports random access. More...
bool | IsSelfInverting () const
| Determines whether the cipher is self-inverting. More...
bool | IsForwardTransformation () const
| Determines if the cipher is being operated in its forward direction. More...
Public Member Functions inherited from CipherModeBase
unsigned int | IVSize () const
| Returns length of the IV accepted by this object. More...
void | SetCipher (BlockCipher &cipher)
| Set external block cipher. More...
void | SetCipherWithIV (BlockCipher &cipher, const byte *iv, int feedbackSize=0)
| Set external block cipher and IV. More...
Public Member Functions inherited from SimpleKeyingInterface
void | SetKeyWithRounds (const byte *key, size_t length, int rounds)
| Sets or reset the key of this object. More...
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv, size_t ivLength)
| Sets or reset the key of this object. More...
void | SetKeyWithIV (const byte *key, size_t length, const byte *iv)
| Sets or reset the key of this object. More...
bool | IsResynchronizable () const
| Determines if the object can be resynchronized. More...
bool | CanUseRandomIVs () const
| Determines if the object can use random IVs. More...
bool | CanUsePredictableIVs () const
| Determines if the object can use random but possibly predictable IVs. More...
bool | CanUseStructuredIVs () const
| Determines if the object can use structured IVs. More...
unsigned int | DefaultIVLength () const
| Provides the default size of an IV. More...
virtual unsigned int | MinIVLength () const
| Provides the minimum size of an IV. More...
virtual unsigned int | MaxIVLength () const
| Provides the maximum size of an IV. More...
virtual void | GetNextIV (RandomNumberGenerator &rng, byte *iv)
| Retrieves a secure IV for the next message. More...
Public Member Functions inherited from StreamTransformation
StreamTransformation & | Ref ()
| Provides a reference to this object. More...
virtual unsigned int | OptimalBlockSize () const
| Provides the input block size most efficient for this cipher. More...
virtual unsigned int | GetOptimalBlockSizeUsed () const
| Provides the number of bytes used in the current block when processing at optimal block size. More...
virtual bool | IsLastBlockSpecial () const
| Determines if the last block receives special processing. More...
void | ProcessString (byte *inoutString, size_t length)
| Encrypt or decrypt a string of bytes. More...
void | ProcessString (byte *outString, const byte *inString, size_t length)
| Encrypt or decrypt a string of bytes. More...
byte | ProcessByte (byte input)
| Encrypt or decrypt a byte. More...
virtual void | Seek (lword pos)
| Seek to an absolute position. More...
Public Member Functions inherited from Algorithm
| Algorithm (bool checkSelfTestStatus=true)
| Interface for all crypto algorithms. More...
Public Member Functions inherited from Clonable
virtual Clonable * | Clone () const
| Copies this object. More...

## Static Public Member Functions
static const char * | StaticAlgorithmName ()
| The algorithm name. More...

## Additional Inherited Members
Public Types inherited from SimpleKeyingInterface
enum | IV_Requirement { UNIQUE_IV = 0, RANDOM_IV, UNPREDICTABLE_RANDOM_IV, INTERNALLY_GENERATED_IV, NOT_RESYNCHRONIZABLE }
| Secure IVs requirements as enumerated values. More...

## Detailed Description

XTS block cipher mode of operation default implementation.

Since
  Crypto++ 8.3

Definition at line 49 of file xts.h.

## Member Function Documentation

## ◆ StaticAlgorithmName()

static const char* XTS_ModeBase::StaticAlgorithmName | ( |  | ) |
| inline static

The algorithm name.

Returns
  the algorithm name

StaticAlgorithmName returns the algorithm's name as a static member function.

Definition at line 56 of file xts.h.

## ◆ AlgorithmName()

std::string XTS_ModeBase::AlgorithmName | ( |  | ) | const
| inline virtual

Provides the name of this algorithm.

Returns
  the standard algorithm name

The standard algorithm name can be a name like `AES` or `AES/GCM`. Some algorithms do not have standard names yet. For example, there is no standard algorithm name for Shoup's ECIES.

Note
  AlgorithmName is not universally implemented yet.

Reimplemented from Algorithm.

Definition at line 61 of file xts.h.

## ◆ AlgorithmProvider()

std::string XTS_ModeBase::AlgorithmProvider | ( |  | ) | const
| inline virtual

Retrieve the provider of this algorithm.

Returns
  the algorithm provider

The algorithm provider can be a name like "C++", "SSE", "NEON", "AESNI", "ARMv8" and "Power8". C++ is standard C++ code. Other labels, like SSE, usually indicate a specialized implementation using instructions from a higher instruction set architecture (ISA). Future labels may include external hardware like a hardware security module (HSM).

Generally speaking Wei Dai's original IA-32 ASM code falls under "SSE2". Labels like "SSSE3" and "SSE4.1" follow after Wei's code and use intrinsics instead of ASM.

Algorithms which combine different instructions or ISAs provide the dominant one. For example on x86 `AES/GCM` returns "AESNI" rather than "CLMUL" or "AES+SSE4.1" or "AES+CLMUL" or "AES+SSE4.1+CLMUL".

Note
  Provider is not universally implemented yet.

Since
  Crypto++ 8.0

Reimplemented from CipherModeBase.

Definition at line 63 of file xts.h.

## ◆ MinKeyLength()

size_t XTS_ModeBase::MinKeyLength | ( |  | ) | const
| inline virtual

Returns smallest valid key length.

Returns
  the minimum key length, in bytes

Reimplemented from CipherModeBase.

Definition at line 66 of file xts.h.

## ◆ MaxKeyLength()

size_t XTS_ModeBase::MaxKeyLength | ( |  | ) | const
| inline virtual

Returns largest valid key length.

Returns
  the maximum key length, in bytes

Reimplemented from CipherModeBase.

Definition at line 68 of file xts.h.

## ◆ DefaultKeyLength()

size_t XTS_ModeBase::DefaultKeyLength | ( |  | ) | const
| inline virtual

Returns default key length.

Returns
  the default key length, in bytes

Reimplemented from CipherModeBase.

Definition at line 70 of file xts.h.

## ◆ GetValidKeyLength()

size_t XTS_ModeBase::GetValidKeyLength | ( | size_t | keylength | ) | const
| inline virtual

Returns a valid key length for the algorithm.

Parameters

  keylength | the size of the key, in bytes

Returns
  the valid key length, in bytes

keylength is provided in bytes, not bits. If keylength is less than MIN_KEYLENGTH, then the function returns MIN_KEYLENGTH. If keylength is greater than MAX_KEYLENGTH, then the function returns MAX_KEYLENGTH. if If keylength is a multiple of KEYLENGTH_MULTIPLE, then keylength is returned. Otherwise, the function returns a lower multiple of KEYLENGTH_MULTIPLE.

Reimplemented from CipherModeBase.

Definition at line 72 of file xts.h.

## ◆ IsValidKeyLength()

bool XTS_ModeBase::IsValidKeyLength | ( | size_t | keylength | ) | const
| inline virtual

Returns whether keylength is a valid key length.

Parameters

  keylength | the requested keylength

Returns
  true if keylength is valid, false otherwise

Internally the function calls GetValidKeyLength()

Reimplemented from CipherModeBase.

Definition at line 74 of file xts.h.

## ◆ ThrowIfInvalidKeyLength()

void XTS_ModeBase::ThrowIfInvalidKeyLength | ( | size_t | length | ) |

Validates the key length.

Parameters

  length | the size of the keying material, in bytes

Exceptions

  InvalidKeyLength | if the key length is invalid

Definition at line 203 of file xts.cpp.

## ◆ BlockSize()

unsigned int XTS_ModeBase::BlockSize | ( |  | ) | const
| inline

Provides the block size of the cipher.

Returns
  the block size of the cipher, in bytes

Definition at line 84 of file xts.h.

## ◆ GetOptimalBlockSize()

unsigned int XTS_ModeBase::GetOptimalBlockSize | ( |  | ) | const
| inline

Provides the input block size most efficient for this cipher.

Returns
  The input block size that is most efficient for the cipher

The base class implementation returns MandatoryBlockSize().

Note
  Optimal input length is `n * OptimalBlockSize() - GetOptimalBlockSizeUsed()` for any `n > 0`.

Definition at line 93 of file xts.h.

## ◆ MinLastBlockSize()

unsigned int XTS_ModeBase::MinLastBlockSize | ( |  | ) | const
| inline virtual

Provides the size of the last block.

Returns
  the minimum size of the last block

MinLastBlockSize() returns the minimum size of the last block. 0 indicates the last block is not special.

MandatoryBlockSize() enlists one of two behaviors. First, if MandatoryBlockSize() returns 1, then the cipher can be streamed and ProcessData() is called with the tail bytes. Second, if MandatoryBlockSize() returns non-0, then the string of bytes is padded to MandatoryBlockSize() according to the padding mode. Then, ProcessData() is called with the padded string of bytes.

Some authenticated encryption modes are not expressed well with MandatoryBlockSize() and MinLastBlockSize(). For example, AES/OCB uses 16-byte blocks (MandatoryBlockSize = 16) and the last block requires special processing (MinLastBlockSize = 0). However, 0 is a valid last block size for OCB and the special processing is custom padding, and not standard PKCS padding. In response an unambiguous IsLastBlockSpecial() was added.

See also
  ProcessData, ProcessLastBlock, MandatoryBlockSize, MinLastBlockSize, BlockPaddingSchemeDef, IsLastBlockSpecial

Reimplemented from StreamTransformation.

Definition at line 95 of file xts.h.

## ◆ OptimalDataAlignment()

unsigned int XTS_ModeBase::OptimalDataAlignment | ( |  | ) | const
| inline virtual

Provides input and output data alignment for optimal performance.

Returns
  the input data alignment that provides optimal performance

See also
  GetAlignment() and OptimalBlockSize()

Reimplemented from CipherModeBase.

Definition at line 97 of file xts.h.

## ◆ ThrowIfInvalidBlockSize()

void XTS_ModeBase::ThrowIfInvalidBlockSize | ( | size_t | length | ) |

Validates the block size.

Parameters

  length | the block size of the cipher, in bytes

Exceptions

  InvalidArgument | if the block size is invalid

If `CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS` is 0, then CIPHER must be a 16-byte block cipher. If `CRYPTOPP_XTS_WIDE_BLOCK_CIPHERS` is non-zero then CIPHER can be 16, 32, 64, or 128-byte block cipher.

Definition at line 190 of file xts.cpp.

## ◆ SetKey()

void XTS_ModeBase::SetKey | ( | const byte * | key,
|  | size_t | length,
|  | const NameValuePairs & | params = `g_nullNameValuePairs`
| ) |  |
| virtual

Sets or reset the key of this object.

Parameters

  key | the key to use when keying the object
  length | the size of the key, in bytes
  params | additional initialization parameters to configure this object

Reimplemented from SimpleKeyingInterface.

Definition at line 210 of file xts.cpp.

## ◆ IVRequirement()

IV_Requirement XTS_ModeBase::IVRequirement | ( |  | ) | const
| inline virtual

Minimal requirement for secure IVs.

Returns
  the secure IV requirement of the algorithm

Implements CipherModeBase.

Definition at line 110 of file xts.h.

## ◆ Resynchronize() [1/2]

void XTS_ModeBase::Resynchronize | ( | const byte * | iv,
|  | int | ivLength = `-1`
| ) |  |
| virtual

Resynchronize with an IV.

Parameters

  iv | the initialization vector
  ivLength | the size of the initialization vector, in bytes

Resynchronize() resynchronizes with an IV provided by the caller. `ivLength=-1` means use IVSize().

Exceptions

  NotImplemented() | if the object does not support resynchronization

Reimplemented from BlockOrientedCipherModeBase.

Definition at line 226 of file xts.cpp.

## ◆ ProcessData()

void XTS_ModeBase::ProcessData | ( | byte * | outString,
|  | const byte * | inString,
|  | size_t | length
| ) |  |
| virtual

Encrypt or decrypt an array of bytes.

Parameters

  outString | the output byte buffer
  inString | the input byte buffer
  length | the size of the input and output byte buffers, in bytes

ProcessData is called with a string of bytes whose size depends on MandatoryBlockSize. Either `inString == outString`, or they must not overlap.

See also
  ProcessData, ProcessLastBlock, MandatoryBlockSize, MinLastBlockSize, BlockPaddingSchemeDef, IsLastBlockSpecial

Implements StreamTransformation.

Definition at line 256 of file xts.cpp.

## ◆ ProcessLastBlock()

size_t XTS_ModeBase::ProcessLastBlock | ( | byte * | outString,
|  | size_t | outLength,
|  | const byte * | inString,
|  | size_t | inLength
| ) |  |
| virtual

Encrypt or decrypt the last block of data.

Parameters

  outString | the output byte buffer
  outLength | the size of the output byte buffer, in bytes
  inString | the input byte buffer
  inLength | the size of the input byte buffer, in bytes

Returns
  the number of bytes used in outString

ProcessLastBlock is used when the last block of data is special and requires handling by the cipher. The current implementation provides an output buffer with a size `inLength+2*MandatoryBlockSize()`. The return value allows the cipher to expand cipher text during encryption or shrink plain text during decryption.

This member function is used by CBC-CTS and OCB modes.

See also
  ProcessData, ProcessLastBlock, MandatoryBlockSize, MinLastBlockSize, BlockPaddingSchemeDef, IsLastBlockSpecial

Reimplemented from StreamTransformation.

Definition at line 368 of file xts.cpp.

## ◆ Resynchronize() [2/2]

void XTS_ModeBase::Resynchronize | ( | word64 | sector,
|  | ByteOrder | order = `BIG_ENDIAN_ORDER`
| ) |  |

Resynchronize the cipher.

Parameters

  sector | a 64-bit sector number
  order | the endian order the word should be written

The Resynchronize() overload was provided for API compatibility with the IEEE P1619 paper.

Definition at line 233 of file xts.cpp.

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

- xts.h
- xts.cpp