I add a few bits from the gettimeofday() microseconds to the PID number
in my random password generator:
/*
*
* YALE University CS Dept.
* Computing Facility, H. Morrow Long
*
* Yale Copyright (c) 1992 Yale University.
* This software is not public domain, it is not to be sold, distributed,
* or reproduced by any means (mechanical, electronic, etc.).
*
* Permission is granted only to use this software so long as it is not
* sold for profit, provided that this notice and the original copyright
* notices are retained. Yale University makes no representations
* about the suitability of this software for any purpose. It is
* provided "as is" without express or implied warranty.
*
* $Log: randpass.c,v $
* Revision 1.3 93/01/05 14:08:53 long
* Now use Salt as seed arg (rather than Clock) for SEED_RANDOM_FUNC().
*
* Revision 1.2 92/03/11 16:01:54 long
* Added better seed value (salt) by incorporating process id number of
* current process and a portion of the microseconds bits if
* gettimeofday() function available. Also will use srandom/random
* over srand/rand if available and turned on.
*
* Revision 1.1 92/03/11 11:44:42 long
* Initial revision
*
*
*/
#include <stdio.h>
/*
* 'define' Macros that should be tweaked for your system.
*/
#define GETTIMEOFDAY /* if your system supports gettimeofday() */
#define RANDOM /* to use srandom/random rather than s/rand */
/* #define DEBUG */
#define MAXPASSWDLEN 8
#define MINUNIQCHARS 5 /* min unique symbols */
/*
* 'define' Macros that should NOT be tweaked for your system.
*/
#define FALSE 0
#define TRUE 1
#ifdef GETTIMEOFDAY
#include <sys/time.h>
unsigned long GetMicroSeconds();
#endif GETTIMEOFDAY
#ifdef RANDOM
#define SEED_RANDOM_FUNC srandom
#define RANDOM_FUNC random
#else
#define SEED_RANDOM_FUNC srand
#define RANDOM_FUNC rand
#endif
# ifndef lint
static char RCSID[] = "$Header: randpass.c,v 1.3 93/01/05 14:08:53 long Exp $";
# endif lint
main()
{
unsigned char PasswdString[MAXPASSWDLEN + 1];
unsigned char Byte;
unsigned long MicroSeconds; /* if gettimeofday supported */
unsigned long Clock;
unsigned long PID;
unsigned long Salt;
int Length;
long time();
time(&Clock);
PID = (unsigned long) getpid();
#ifdef GETTIMEOFDAY
Clock = GetMicroSeconds();
#ifdef DEBUG
fprintf(stderr, "DEBUG: Clock = GetMicroSeconds() = %u\n", Clock );
#endif
#endif
Salt = ( PID << 16) | ( Clock & 0x0000ffff);
#ifdef DEBUG
fprintf(stderr, "DEBUG: Salt = %u\n", Salt );
#endif
SEED_RANDOM_FUNC(Salt);
do
{
for (Length = 0; Length < MAXPASSWDLEN; Length++)
{
PasswdString[Length] = '\0';
while ( PasswdString[Length] == '\0' )
{
Byte = ( ( RANDOM_FUNC()) % 127 );
if ( ! ( isprint(Byte) ) ) continue;
if ( ( isspace(Byte) ) ) continue;
if (Length > 0 )
if ( ( (isupper(PasswdString[Length-1])) &&
(isupper(Byte) ) ) ||
( (islower(PasswdString[Length-1])) &&
(islower(Byte) ) ) ||
( (isdigit(PasswdString[Length-1])) &&
(isdigit(Byte) ) ) ||
( (ispunct(PasswdString[Length-1])) &&
(ispunct(Byte) ) ) )
continue;
PasswdString[Length] = Byte;
#ifdef DEBUG
fprintf(stderr, "DEBUG: PasswdString[%d] = %c\n", Length, Byte);
#endif
}
}
PasswdString[Length] = '\0';
} while ( UniqCharsInString( PasswdString ) < MINUNIQCHARS );
printf("You will have 10 seconds to write or copy this password.\n");
printf("Password generated is = %8.8s ", PasswdString);
fflush(stdout);
sleep(10);
printf("\rPassword generated is = XXXXXXXXX\n");
/* erase memory for paranoia */
while (Length > -1 )
PasswdString[Length--] = '\0';
}
UniqCharsInString( String )
unsigned char *String;
{
int Counter, Index, Position, Length, UniqueFlag;
#ifdef DEBUG
fprintf(stderr, "DEBUG: Inside UniqCharsInString(\"%s\")\n", String);
#endif
Length = strlen(String);
for ( Position = 0 ; Position < Length; Position++)
if (Position == 0)
Counter = 1;
else
{
UniqueFlag = TRUE;
for ( Index = 0 ; Index < Position ; Index++)
if ( String[Index] == String[Position] )
UniqueFlag = FALSE;
Counter += UniqueFlag ;
}
#ifdef DEBUG
fprintf(stderr, "DEBUG:\tCounter = %d\n", Counter);
#endif
return(Counter);
}
#ifdef GETTIMEOFDAY
unsigned long GetMicroSeconds()
{
struct timeval TimeVal;
gettimeofday(&TimeVal, (struct timezone *) 0 );
return(TimeVal.tv_usec);
}
#endif
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