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random.c
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/*
* Copyright (c) 2013, SERDAR GOKCEN <[email protected]>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by "asdr".
* 4. Neither the name of "asdr" nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY SERDAR GOKCEN ''AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL SERDAR GOKCEN BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <string.h>
#include "random.h"
int __pca_global_random_file = -1;
void random_open( void ) {
if ( __pca_global_random_file == -1 )
{
__pca_global_random_file = open( PSEUDORANDOM_KEY_SOURCE, O_RDONLY );
}
}
void random_get_value( long* random_value ) {
if ( __pca_global_random_file == -1)
{
*random_value = rand();
}
else
{
read( __pca_global_random_file, random_value, sizeof(long) );
if ( *random_value < 0 )
*random_value *= -1;
//additional ( not much readable ) math.abs value
//*random_value = ((*random_value>>(((sizeof(long))<<3)-1)) ^ *random_value);
//*random_value -= (*random_value>>(((sizeof(long))<<3)-1));
}
}
char* random_generate_text( int length ) {
int i=0, ch;
long int random_value;
char* buffer = (char*) malloc(sizeof(char) * (length+1));
if ( buffer == NULL )
return NULL;
for ( ; i<length; ++i )
{
random_get_value( &random_value );
// char or numeric
if ( random_value % 2 == 0 )
{
random_get_value( &random_value );
if ( random_value % 2 == 0 )
{
random_get_value( &random_value );
ch = 'A' + random_value%26;
}
else
{
random_get_value( &random_value );
ch = 'a' + random_value%26;
}
}
else
{
random_get_value( &random_value );
ch = '0' + random_value%10;
}
buffer[i] = ch;
}
buffer[length] = '\0';
return buffer;
}
char* random_generate_key( int bit_length ) {
int i=0, k=0, ch;
long int random_value;
char* buffer = (char*) malloc( sizeof(char) * (bit_length / 8) );
if ( buffer == NULL )
return NULL;
for ( ; i<bit_length; ++i, k=i/8 )
{
random_get_value( &random_value );
ch = random_value%2;
buffer[k] |= (ch << i%8);
}
buffer[k+1] = '\0';
return buffer;
}
void random_close() {
close( __pca_global_random_file );
__pca_global_random_file = -1;
}