CRC32Hash Class Reference

CRC32 checksum (POSIX.2; not a cryptographically secure hash). More...

#include <crc32hash.h>

Inheritance diagram for CRC32Hash:

[legend]Collaboration diagram for CRC32Hash:

[legend]List of all members.

Public Member Functions
	CRC32Hash ()
	Constructor for CRC32 checksum.
	~CRC32Hash ()
	Destructor cleans up the hash state.
const Parameters *	GetPar () const
	Get parameters of this hash algo; see base clas.
uint64	FedBytes () const
	Returns number of fed bytes; see base class.
void	reset ()
	Reset has algo; see base class.
void	feed (const char *buf, size_t len)
	Feed the hash algo with data; see base class.
void	final ()
	Finish hash computation; see base class.
void	GetHash (char *buf) const
	Get current has value; see base class.
Static Public Attributes
const Parameters	par
	Parameters of the hash algo.
Private Member Functions
	CRC32Hash (const CRC32Hash &)
	Do not use these:.
void	operator= (const CRC32Hash &)
Private Attributes
uint32	state
	hash status; hash value
Static Private Attributes
const uint32	crc32table [256]
	1kb CRC precomputed table. This is static and used read-only.

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Detailed Description

CRC32 checksum (POSIX.2; not a cryptographically secure hash).

Author:

Wolfgang Wieser ] wwieser (a) gmx <*> de [

The CRC32 algorithm provides a quite good way for data modification checks when e.g. transmitting files over insecure lines. It is not cryptographically secure, i.e. a malicious party can quite easily create two data sets with the same CRC32 checksum but with 4 bytes of length and an enormous speed (compared to the crypto hashes) it provides a nice way to check data against "non-malicious", "random" modifications.

This implementation of the class uses an internal CRC32 hash table of the size 1024 bytes. However, the table is const and static (compiled-in) [i.e. thread-safe].

NOTE: This class is NOT "C++-safe" and you should generally be careful with cryptographic data, so it is best to manage (de)allocation of these objects in a higher order.

Definition at line 52 of file crc32hash.h.

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Constructor & Destructor Documentation

CRC32Hash::CRC32Hash (  const CRC32Hash &   )  [private]

Do not use these:.

CRC32Hash::CRC32Hash (   )  [inline]

Constructor for CRC32 checksum. Definition at line 70 of file crc32hash.h. References reset().

CRC32Hash::~CRC32Hash (   )  [inline]

Destructor cleans up the hash state. Definition at line 73 of file crc32hash.h. References reset().

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Member Function Documentation

uint64 CRC32Hash::FedBytes (   )  const [inline, virtual]

Returns number of fed bytes; see base class. Reimplemented from SecureHashBase. Definition at line 81 of file crc32hash.h. References uint64.

void CRC32Hash::feed (  const char *  buf, size_t  len )  [virtual]

Feed the hash algo with data; see base class. Reimplemented from SecureHashBase. Definition at line 136 of file crc32hash.cc. References state, and uint32.

void CRC32Hash::final (   )  [virtual]

Finish hash computation; see base class. Reimplemented from SecureHashBase. Definition at line 148 of file crc32hash.cc. References state, and uint64.

void CRC32Hash::GetHash (  char *  buf  )  const [virtual]

Get current has value; see base class. Reimplemented from SecureHashBase. Definition at line 115 of file crc32hash.cc. References state, and uint32.

const Parameters* CRC32Hash::GetPar (   )  const [inline, virtual]

Get parameters of this hash algo; see base clas. Reimplemented from SecureHashBase. Definition at line 77 of file crc32hash.h. References par.

void CRC32Hash::operator= (  const CRC32Hash &   )  [private]

void CRC32Hash::reset (   )  [virtual]

Reset has algo; see base class. Reimplemented from SecureHashBase. Definition at line 126 of file crc32hash.cc. References Assert, crc32table, and state. Referenced by CRC32Hash(), and ~CRC32Hash().

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Member Data Documentation

const uint32 CRC32Hash::crc32table [static, private]

1kb CRC precomputed table. This is static and used read-only. Definition at line 35 of file crc32hash.cc. Referenced by reset().

const SecureHashBase::Parameters CRC32Hash::par [static]

Initial value: { INIT_FIELD(hash_size) 4, INIT_FIELD(block_size) 4, INIT_FIELD(hash_ID) 0x3000, INIT_FIELD(name) "CRC32" } Parameters of the hash algo. Reimplemented from SecureHashBase. Definition at line 27 of file crc32hash.cc. Referenced by GetPar().

uint32 CRC32Hash::state [private]

hash status; hash value Definition at line 59 of file crc32hash.h. Referenced by feed(), final(), GetHash(), and reset().

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

• /ray/src/lib/crypto/crc32hash.h
• /ray/src/lib/crypto/crc32hash.cc

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