HashTransformation Class Referenceabstract

Interface for hash functions and data processing part of MACs. More...

Inheritance diagram for HashTransformation:

## Public Member Functions

HashTransformation & | Ref ()
| Provides a reference to this object. More...
virtual void | Update (const byte *input, size_t length)=0
| Updates a hash with additional input. More...
virtual byte * | CreateUpdateSpace (size_t &size)
| Request space which can be written into by the caller. More...
virtual void | Final (byte *digest)
| Computes the hash of the current message. More...
virtual void | Restart ()
| Restart the hash. More...
virtual unsigned int | DigestSize () const =0
| Provides the digest size of the hash. More...
unsigned int | TagSize () const
| Provides the tag size of the hash. More...
virtual unsigned int | BlockSize () const
| Provides the block size of the compression function. More...
virtual unsigned int | OptimalBlockSize () const
| Provides the input block size most efficient for this hash. More...
virtual unsigned int | OptimalDataAlignment () const
| Provides input and output data alignment for optimal performance. More...
virtual void | CalculateDigest (byte *digest, const byte *input, size_t length)
| Updates the hash with additional input and computes the hash of the current message. More...
virtual bool | Verify (const byte *digest)
| Verifies the hash of the current message. More...
virtual bool | VerifyDigest (const byte *digest, const byte *input, size_t length)
| Updates the hash with additional input and verifies the hash of the current message. More...
virtual void | TruncatedFinal (byte *digest, size_t digestSize)=0
| Computes the hash of the current message. More...
virtual void | CalculateTruncatedDigest (byte *digest, size_t digestSize, const byte *input, size_t length)
| Updates the hash with additional input and computes the hash of the current message. More...
virtual bool | TruncatedVerify (const byte *digest, size_t digestLength)
| Verifies the hash of the current message. More...
virtual bool | VerifyTruncatedDigest (const byte *digest, size_t digestLength, const byte *input, size_t length)
| Updates the hash with additional input and verifies the hash of the current message. More...
Public Member Functions inherited from Algorithm
| Algorithm (bool checkSelfTestStatus=true)
| Interface for all crypto algorithms. More...
virtual std::string | AlgorithmName () const
| Provides the name of this algorithm. More...
Public Member Functions inherited from Clonable
virtual Clonable * | Clone () const
| Copies this object. More...

## Detailed Description

Interface for hash functions and data processing part of MACs.

HashTransformation objects are stateful. They are created in an initial state, change state as Update() is called, and return to the initial state when Final() is called. This interface allows a large message to be hashed in pieces by calling Update() on each piece followed by calling Final().

See also
  HashFilter(), HashVerificationFilter()

Definition at line 922 of file cryptlib.h.

## Member Function Documentation

## Ref()

HashTransformation& HashTransformation::Ref | ( |  | ) |

inline

Provides a reference to this object.

Returns
  A reference to this object

Useful for passing a temporary object to a function that takes a non-const reference

Definition at line 932 of file cryptlib.h.

## Update()

virtual void HashTransformation::Update | ( | const byte * | input,
|  | size_t | length
| ) |  |

pure virtual

Updates a hash with additional input.

Parameters

  input | the additional input as a buffer
  length | the size of the buffer, in bytes

Implemented in PK_MessageAccumulatorBase, BLAKE2_Base< W, T_64bit >, BLAKE2_Base< word32, false >, BLAKE2_Base< word64, true >, CRC32C, Keccak, SHA3, AuthenticatedSymmetricCipherBase, TruncatedHashTemplate< T >, CRC32, DMAC_Base< T >, HMAC_Base, CMAC_Base, CBC_MAC_Base, Adler32, Weak::MD2, and NullHash.

## CreateUpdateSpace()

virtual byte* HashTransformation::CreateUpdateSpace | ( | size_t & | size | ) |

inline virtual

Request space which can be written into by the caller.

Parameters

  size | the requested size of the buffer

The purpose of this method is to help avoid extra memory allocations.

size is an IN and OUT parameter and used as a hint. When the call is made, size is the requested size of the buffer. When the call returns, size is the size of the array returned to the caller.

The base class implementation sets size to 0 and returns NULL.

Note
  Some objects, like ArraySink, cannot create a space because its fixed.

Definition at line 947 of file cryptlib.h.

## Final()

virtual void HashTransformation::Final | ( | byte * | digest | ) |

inline virtual

Computes the hash of the current message.

Parameters

  digest | a pointer to the buffer to receive the hash

Final() restarts the hash for a new message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 954 of file cryptlib.h.

## Restart()

virtual void HashTransformation::Restart | ( |  | ) |

inline virtual

Restart the hash.

Discards the current state, and restart for a new message

Reimplemented in BLAKE2_Base< W, T_64bit >, BLAKE2_Base< word32, false >, BLAKE2_Base< word64, true >, Keccak, SHA3, AuthenticatedSymmetricCipherBase, TruncatedHashTemplate< T >, and HMAC_Base.

Definition at line 959 of file cryptlib.h.

## DigestSize()

virtual unsigned int HashTransformation::DigestSize | ( |  | ) | const

pure virtual

Provides the digest size of the hash.

Returns
  the digest size of the hash.

Implemented in PK_MessageAccumulator, BLAKE2_Base< W, T_64bit >, IteratedHashWithStaticTransform< T_HashWordType, T_Endianness, T_BlockSize, T_StateSize, T_Transform, T_DigestSize, T_StateAligned >, CRC32C, GCM_Base, Keccak, CCM_Base, EAX_Base, Weak::PanamaHash< B >, SHA3, TruncatedHashTemplate< T >, CRC32, VMAC_Base, DMAC_Base< T >, HMAC_Base, CMAC_Base, CBC_MAC_Base, TTMAC_Base, Adler32, Weak::MD2, and NullHash.

## TagSize()

unsigned int HashTransformation::TagSize | ( |  | ) | const

inline

Provides the tag size of the hash.

Returns
  the tag size of the hash.

Same as DigestSize().

Definition at line 969 of file cryptlib.h.

## BlockSize()

virtual unsigned int HashTransformation::BlockSize | ( |  | ) | const

inline virtual

Provides the block size of the compression function.

Returns
  the block size of the compression function, in bytes

BlockSize() will return 0 if the hash is not block based. For example, SHA3 is a recursive hash (not an iterative hash), and it does not have a block size.

Reimplemented in IteratedHash< T_HashWordType, T_Endianness, T_BlockSize, T_Base >, VMAC_Base, and Weak::MD2.

Definition at line 975 of file cryptlib.h.

## OptimalBlockSize()

virtual unsigned int HashTransformation::OptimalBlockSize | ( |  | ) | const

inline virtual

Provides the input block size most efficient for this hash.

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

The base class implementation returns MandatoryBlockSize().

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

Reimplemented in CMAC_Base, and HMAC_Base.

Definition at line 982 of file cryptlib.h.

## OptimalDataAlignment()

unsigned int HashTransformation::OptimalDataAlignment | ( |  | ) | const

virtual

Provides input and output data alignment for optimal performance.

Returns
  the input data alignment that provides optimal performance

Reimplemented in BLAKE2_Base< W, T_64bit >, Keccak, GCM_Base, SHA3, CCM_Base, EAX_Base, VMAC_Base, and CMAC_Base.

Definition at line 243 of file cryptlib.cpp.

## CalculateDigest()

virtual void HashTransformation::CalculateDigest | ( | byte * | digest,
|  | const byte * | input,
|  | size_t | length
| ) |  |

inline virtual

Updates the hash with additional input and computes the hash of the current message.

Parameters

  digest | a pointer to the buffer to receive the hash
  input | the additional input as a buffer
  length | the size of the buffer, in bytes

Use this if your input is in one piece and you don't want to call Update() and Final() separately

CalculateDigest() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 997 of file cryptlib.h.

## Verify()

virtual bool HashTransformation::Verify | ( | const byte * | digest | ) |

inline virtual

Verifies the hash of the current message.

Parameters

  digest | a pointer to the buffer of an existing hash

Returns
  `true` if the existing hash matches the computed hash, `false` otherwise

Exceptions

  ThrowIfInvalidTruncatedSize() | if the existing hash's size exceeds DigestSize()

Verify() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is a constant time comparison function. digestLength cannot exceed DigestSize().

Verify() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 1009 of file cryptlib.h.

## VerifyDigest()

virtual bool HashTransformation::VerifyDigest | ( | const byte * | digest,
|  | const byte * | input,
|  | size_t | length
| ) |  |

inline virtual

Updates the hash with additional input and verifies the hash of the current message.

Parameters

  digest | a pointer to the buffer of an existing hash
  input | the additional input as a buffer
  length | the size of the buffer, in bytes

Returns
  `true` if the existing hash matches the computed hash, `false` otherwise

Exceptions

  ThrowIfInvalidTruncatedSize() | if the existing hash's size exceeds DigestSize()

Use this if your input is in one piece and you don't want to call Update() and Verify() separately

VerifyDigest() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is a constant time comparison function. digestLength cannot exceed DigestSize().

VerifyDigest() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 1025 of file cryptlib.h.

## TruncatedFinal()

virtual void HashTransformation::TruncatedFinal | ( | byte * | digest,
|  | size_t | digestSize
| ) |  |

pure virtual

Computes the hash of the current message.

Parameters

  digest | a pointer to the buffer to receive the hash
  digestSize | the size of the truncated digest, in bytes

TruncatedFinal() call Final() and then copies digestSize bytes to digest

TruncatedFinal() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Implemented in VMAC_Base, DMAC_Base< T >, HMAC_Base, CMAC_Base, TTMAC_Base, CBC_MAC_Base, AuthenticatedSymmetricCipherBase, BLAKE2_Base< W, T_64bit >, BLAKE2_Base< word32, false >, BLAKE2_Base< word64, true >, CRC32C, Keccak, Weak::PanamaHash< B >, Weak::PanamaHash< LittleEndian >, SHA3, CRC32, Adler32, Weak::MD2, Tiger, Whirlpool, PK_MessageAccumulator, TruncatedHashTemplate< T >, and NullHash.

## CalculateTruncatedDigest()

virtual void HashTransformation::CalculateTruncatedDigest | ( | byte * | digest,
|  | size_t | digestSize,
|  | const byte * | input,
|  | size_t | length
| ) |  |

inline virtual

Updates the hash with additional input and computes the hash of the current message.

Parameters

  digest | a pointer to the buffer to receive the hash
  digestSize | the length of the truncated hash, in bytes
  input | the additional input as a buffer
  length | the size of the buffer, in bytes

Use this if your input is in one piece and you don't want to call Update() and CalculateDigest() separately.

CalculateTruncatedDigest() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 1047 of file cryptlib.h.

## TruncatedVerify()

bool HashTransformation::TruncatedVerify | ( | const byte * | digest,
|  | size_t | digestLength
| ) |  |

virtual

Verifies the hash of the current message.

Parameters

  digest | a pointer to the buffer of an existing hash
  digestLength | the size of the truncated hash, in bytes

Returns
  `true` if the existing hash matches the computed hash, `false` otherwise

Exceptions

  ThrowIfInvalidTruncatedSize() | if digestLength exceeds DigestSize()

TruncatedVerify() is a truncated version of Verify(). It can operate on a buffer smaller than DigestSize(). However, digestLength cannot exceed DigestSize().

Verify() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is a constant time comparison function. digestLength cannot exceed DigestSize().

TruncatedVerify() restarts the hash for the next message.

Reimplemented in TruncatedHashTemplate< T >, and NullHash.

Definition at line 412 of file cryptlib.cpp.

## VerifyTruncatedDigest()

virtual bool HashTransformation::VerifyTruncatedDigest | ( | const byte * | digest,
|  | size_t | digestLength,
|  | const byte * | input,
|  | size_t | length
| ) |  |

inline virtual

Updates the hash with additional input and verifies the hash of the current message.

Parameters

  digest | a pointer to the buffer of an existing hash
  digestLength | the size of the truncated hash, in bytes
  input | the additional input as a buffer
  length | the size of the buffer, in bytes

Returns
  `true` if the existing hash matches the computed hash, `false` otherwise

Exceptions

  ThrowIfInvalidTruncatedSize() | if digestLength exceeds DigestSize()

Use this if your input is in one piece and you don't want to call Update() and TruncatedVerify() separately.

VerifyTruncatedDigest() is a truncated version of VerifyDigest(). It can operate on a buffer smaller than DigestSize(). However, digestLength cannot exceed DigestSize().

VerifyTruncatedDigest() restarts the hash for the next message.

Precondition
  `COUNTOF(digest) == DigestSize()` or `COUNTOF(digest) == HASH::DIGESTSIZE` ensures the output byte buffer is large enough for the digest.

Definition at line 1076 of file cryptlib.h.

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

- cryptlib.h
- cryptlib.cpp