CRC32 Class Reference

CRC-32 Checksum Calculation. More...

#include <crc.h>

Inheritance diagram for CRC32:

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

Static Public Member Functions
static const char *	StaticAlgorithmName ()

Static Public Attributes
static const int	DIGESTSIZE = 4

Detailed Description

CRC-32 Checksum Calculation.

Uses CRC polynomial 0xEDB88320

Definition at line 25 of file crc.h.

Constructor & Destructor Documentation

CRC32()

CRC32::CRC32

(

)

Definition at line 142 of file crc.cpp.

Member Function Documentation

Update()

void CRC32::Update ( const byte * input, size_t length )

virtual

Updates a hash with additional input.

Parameters

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

Implements HashTransformation.

Definition at line 147 of file crc.cpp.

TruncatedFinal()

void CRC32::TruncatedFinal ( byte * digest, size_t digestSize )

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() calls Final() and then copies digestSize bytes to digest. The hash is restarted the hash for the next message.

Precondition

COUNTOF(digest) <= DigestSize() or COUNTOF(digest) <= HASH::DIGESTSIZE ensures the output byte buffer is a valid size.

Implements HashTransformation.

Definition at line 178 of file crc.cpp.

DigestSize()

unsigned int CRC32::DigestSize ( ) const

inlinevirtual

Provides the digest size of the hash.

Returns

the digest size of the hash.

Implements HashTransformation.

Definition at line 32 of file crc.h.

StaticAlgorithmName()

static const char * CRC32::StaticAlgorithmName ( )

inlinestatic

Definition at line 33 of file crc.h.

AlgorithmName()

std::string CRC32::AlgorithmName ( ) const

inlinevirtual

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 34 of file crc.h.

UpdateByte()

void CRC32::UpdateByte ( byte b )

inline

Updates a CRC with additional input.

Parameters

b	the additional input as a byte

Definition at line 38 of file crc.h.

GetCrcByte()

byte CRC32::GetCrcByte ( size_t i ) const

inline

Retrieves the i-th byte of the CRC.

Parameters

i	the additional input as a byte

Returns

the byte at the i-th position

Definition at line 43 of file crc.h.

AlgorithmProvider()

std::string CRC32::AlgorithmProvider ( ) const

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 Algorithm.

Definition at line 133 of file crc.cpp.

Member Data Documentation

DIGESTSIZE

const int CRC32::DIGESTSIZE = 4

static

Definition at line 28 of file crc.h.

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

• crc.h
• crc.cpp