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

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/*
 * lib/crypto/crc32hash.cc
 * 
 * Implementation of class CRC32Hash, a class for computation of 
 * the CRC32 checksum (POSIX.2) which is not a cryptographically secure 
 * hash algorithm. 
 * 
 * Copyright (c) 2004 by Wolfgang Wieser ] wwieser (a) gmx <*> de [ 
 * 
 * This code is based on the algorithm found in the cksum(1) program 
 * bundeled with the GNU coreutils, written by 
 * Q. Frank Xia, qx@math.columbia.edu
 * 
 * This file may be distributed and/or modified under the terms of the 
 * GNU General Public License version 2 as published by the Free Software 
 * Foundation. (See COPYING.GPL for details.)
 * 
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * 
 */

#include "crc32hash.h"


// Static data initialisation: 
const SecureHashBase::Parameters CRC32Hash::par=
{
    INIT_FIELD(hash_size) 4,
    INIT_FIELD(block_size) 4,
    INIT_FIELD(hash_ID) 0x3000,
    INIT_FIELD(name) "CRC32"
};

const uint32 CRC32Hash::crc32table[256]=
{
    0x00000000U,
    0x04c11db7U, 0x09823b6eU, 0x0d4326d9U, 0x130476dcU, 0x17c56b6bU,
    0x1a864db2U, 0x1e475005U, 0x2608edb8U, 0x22c9f00fU, 0x2f8ad6d6U,
    0x2b4bcb61U, 0x350c9b64U, 0x31cd86d3U, 0x3c8ea00aU, 0x384fbdbdU,
    0x4c11db70U, 0x48d0c6c7U, 0x4593e01eU, 0x4152fda9U, 0x5f15adacU,
    0x5bd4b01bU, 0x569796c2U, 0x52568b75U, 0x6a1936c8U, 0x6ed82b7fU,
    0x639b0da6U, 0x675a1011U, 0x791d4014U, 0x7ddc5da3U, 0x709f7b7aU,
    0x745e66cdU, 0x9823b6e0U, 0x9ce2ab57U, 0x91a18d8eU, 0x95609039U,
    0x8b27c03cU, 0x8fe6dd8bU, 0x82a5fb52U, 0x8664e6e5U, 0xbe2b5b58U,
    0xbaea46efU, 0xb7a96036U, 0xb3687d81U, 0xad2f2d84U, 0xa9ee3033U,
    0xa4ad16eaU, 0xa06c0b5dU, 0xd4326d90U, 0xd0f37027U, 0xddb056feU,
    0xd9714b49U, 0xc7361b4cU, 0xc3f706fbU, 0xceb42022U, 0xca753d95U,
    0xf23a8028U, 0xf6fb9d9fU, 0xfbb8bb46U, 0xff79a6f1U, 0xe13ef6f4U,
    0xe5ffeb43U, 0xe8bccd9aU, 0xec7dd02dU, 0x34867077U, 0x30476dc0U,
    0x3d044b19U, 0x39c556aeU, 0x278206abU, 0x23431b1cU, 0x2e003dc5U,
    0x2ac12072U, 0x128e9dcfU, 0x164f8078U, 0x1b0ca6a1U, 0x1fcdbb16U,
    0x018aeb13U, 0x054bf6a4U, 0x0808d07dU, 0x0cc9cdcaU, 0x7897ab07U,
    0x7c56b6b0U, 0x71159069U, 0x75d48ddeU, 0x6b93dddbU, 0x6f52c06cU,
    0x6211e6b5U, 0x66d0fb02U, 0x5e9f46bfU, 0x5a5e5b08U, 0x571d7dd1U,
    0x53dc6066U, 0x4d9b3063U, 0x495a2dd4U, 0x44190b0dU, 0x40d816baU,
    0xaca5c697U, 0xa864db20U, 0xa527fdf9U, 0xa1e6e04eU, 0xbfa1b04bU,
    0xbb60adfcU, 0xb6238b25U, 0xb2e29692U, 0x8aad2b2fU, 0x8e6c3698U,
    0x832f1041U, 0x87ee0df6U, 0x99a95df3U, 0x9d684044U, 0x902b669dU,
    0x94ea7b2aU, 0xe0b41de7U, 0xe4750050U, 0xe9362689U, 0xedf73b3eU,
    0xf3b06b3bU, 0xf771768cU, 0xfa325055U, 0xfef34de2U, 0xc6bcf05fU,
    0xc27dede8U, 0xcf3ecb31U, 0xcbffd686U, 0xd5b88683U, 0xd1799b34U,
    0xdc3abdedU, 0xd8fba05aU, 0x690ce0eeU, 0x6dcdfd59U, 0x608edb80U,
    0x644fc637U, 0x7a089632U, 0x7ec98b85U, 0x738aad5cU, 0x774bb0ebU,
    0x4f040d56U, 0x4bc510e1U, 0x46863638U, 0x42472b8fU, 0x5c007b8aU,
    0x58c1663dU, 0x558240e4U, 0x51435d53U, 0x251d3b9eU, 0x21dc2629U,
    0x2c9f00f0U, 0x285e1d47U, 0x36194d42U, 0x32d850f5U, 0x3f9b762cU,
    0x3b5a6b9bU, 0x0315d626U, 0x07d4cb91U, 0x0a97ed48U, 0x0e56f0ffU,
    0x1011a0faU, 0x14d0bd4dU, 0x19939b94U, 0x1d528623U, 0xf12f560eU,
    0xf5ee4bb9U, 0xf8ad6d60U, 0xfc6c70d7U, 0xe22b20d2U, 0xe6ea3d65U,
    0xeba91bbcU, 0xef68060bU, 0xd727bbb6U, 0xd3e6a601U, 0xdea580d8U,
    0xda649d6fU, 0xc423cd6aU, 0xc0e2d0ddU, 0xcda1f604U, 0xc960ebb3U,
    0xbd3e8d7eU, 0xb9ff90c9U, 0xb4bcb610U, 0xb07daba7U, 0xae3afba2U,
    0xaafbe615U, 0xa7b8c0ccU, 0xa379dd7bU, 0x9b3660c6U, 0x9ff77d71U,
    0x92b45ba8U, 0x9675461fU, 0x8832161aU, 0x8cf30badU, 0x81b02d74U,
    0x857130c3U, 0x5d8a9099U, 0x594b8d2eU, 0x5408abf7U, 0x50c9b640U,
    0x4e8ee645U, 0x4a4ffbf2U, 0x470cdd2bU, 0x43cdc09cU, 0x7b827d21U,
    0x7f436096U, 0x7200464fU, 0x76c15bf8U, 0x68860bfdU, 0x6c47164aU,
    0x61043093U, 0x65c52d24U, 0x119b4be9U, 0x155a565eU, 0x18197087U,
    0x1cd86d30U, 0x029f3d35U, 0x065e2082U, 0x0b1d065bU, 0x0fdc1becU,
    0x3793a651U, 0x3352bbe6U, 0x3e119d3fU, 0x3ad08088U, 0x2497d08dU,
    0x2056cd3aU, 0x2d15ebe3U, 0x29d4f654U, 0xc5a92679U, 0xc1683bceU,
    0xcc2b1d17U, 0xc8ea00a0U, 0xd6ad50a5U, 0xd26c4d12U, 0xdf2f6bcbU,
    0xdbee767cU, 0xe3a1cbc1U, 0xe760d676U, 0xea23f0afU, 0xeee2ed18U,
    0xf0a5bd1dU, 0xf464a0aaU, 0xf9278673U, 0xfde69bc4U, 0x89b8fd09U,
    0x8d79e0beU, 0x803ac667U, 0x84fbdbd0U, 0x9abc8bd5U, 0x9e7d9662U,
    0x933eb0bbU, 0x97ffad0cU, 0xafb010b1U, 0xab710d06U, 0xa6322bdfU,
    0xa2f33668U, 0xbcb4666dU, 0xb8757bdaU, 0xb5365d03U, 0xb1f740b4U
};


#if 0
// This could be used to generate the table above. (Untested!) 
// See coreutils / cksum.c for more information. 
char CRC32Hash::_GenTable()
{
    for(uint32 i=0; i<256; i++)
    {
        uint32 crc=i;
        
        for(int j=0; j<8; j++)
        {
            crc >>= 1;
            if(crc & 1U)  crc ^= 0xedb88320U;
        }
        
        crc32table[i] = crc;
    }
    
    return(1);
}
#endif


void CRC32Hash::GetHash(char *buf) const
{
    register unsigned char *hsh=(unsigned char*)buf+3;
    register uint32 j=state;
    *(hsh--)=(unsigned char)(j & 0xffU);  j>>=8;
    *(hsh--)=(unsigned char)(j & 0xffU);  j>>=8;
    *(hsh--)=(unsigned char)(j & 0xffU);  j>>=8;
    *(hsh  )=(unsigned char)(j & 0xffU);
}


void CRC32Hash::reset()
{
    length=0LLU;
    state=0U;
    
    // Make sure we initialized. 
    Assert(crc32table[1]!=0);
}


void CRC32Hash::feed(const char *_buf,size_t len)
{
    const unsigned char *buf=(const unsigned char*)_buf;
    register uint32 s=state;
    for(const unsigned char *bend=buf+len; buf<bend; buf++)
    {  s = (s<<8) ^ crc32table[ ((unsigned char)(s>>24))^*buf ];  }
    state=s;
    
    length+=len;
}


void CRC32Hash::final()
{
    uint64 bytes_read=length;
    
    while(bytes_read)
    {
        unsigned char val = (unsigned char)(bytes_read & 0xffU);
        state = (state<<8) ^ crc32table[ ((unsigned char)(state>>24)) ^ val ];
        bytes_read >>= 8;
    }
    
    state = ~state & 0xffffffffU;  // 0xffffffff is unneeded (optimized away)
}

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