swordfish --- a password generator Post: 302081450

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Special Forums Cybersecurity swordfish --- a password generator Post 302081450 by Perderabo on Tuesday 25th of July 2006 11:19:23 AM

07-25-2006

Administrator Emeritus

I will post a new copy of swordfish making these changes:

Code:

In the weak_start_tigershark function: the line in green is new.

function weak_start_tigershark
{
        typeset -i  i final duration
        ((final=SECONDS+2))

        while((SECONDS < final)) ; do
                i=$RANDOM
        done

        ((Carry=0))
        ((X0=$$))
        ((X1=RANDOM))
        ((X2=RANDOM))
        ((X3=RANDOM))
        ((DEBUG)) && echo weakstart X3=$X3 X2=$X2 X1=$X1 X0=$X0 Carry=$Carry
        Sum=0
        ((Stigershark=Stigershark+1))
        return 0
}


In the Main section: The lines in red go away:

if [[ $Entropy = $ZeroEntropy ]] ; then
                echo "********************************" >&2
                echo "*                              *" >&2
                echo "*  Warning:  Entropy is zero!  *" >&2
                echo "*                              *" >&2
                echo "********************************" >&2
                echo generating weak entropy... >&2
                weak_start_tigershark
                status_tigershark
                entropy_generator 1 array
                echo  Entropy = ${Entropy}
                NeedMoreEntropy=1
fi

It is too early in the program to call status_tigershark since linecount has not be initialized and also it is sending unsolicted output to stdout. And that "echo Entropy" should have been directed to stderr as well. The remaining error message should be enough to call attention to the fact that swordfish is not operating in an optimum manner. And the user can always turn on debug mode for more output.

Yes, my intent is that swordfish be invoked always in the same directory. swordfish maintains an entropy file which is random data used to initialize the internal random number generator. But the first time the random number generator is called, there won't be an entropy file. So swordfish will initialize the RNG from /dev/urandom or /dev/random. If neither of those is available then swordfish is stuck with no decent source of initial random numbers. So it invokes the internal ksh RANDOM routine to get a few random numbers and it uses its current PID for one more random number. It first spends a couple of seconds burning off some of KSH's random numbers so it is not as bad as it might otherwise be. But it still complains about the situation. This is what is happening to you. Even HP-UX finally implemented /dev/random in 11.23. What OS are you using without a /dev/random?

If you really want to call swordfish from arbitrary directories, you could change the line:
ENTROPYFILE=swordfish.ent
to be an obsolute path to your entropy file. But remember, if other people can read your entropy file, they might be able to predict the passwords it
will generate.

Perderabo

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LEARN ABOUT DEBIAN

arc4rand

RANDOM(9)						   BSD Kernel Developer's Manual						 RANDOM(9)

NAME

     arc4rand, arc4random, random, read_random, srandom -- supply pseudo-random numbers

SYNOPSIS

     #include <sys/libkern.h>

     void
     srandom(u_long seed);

     u_long
     random(void);

     void
     arc4rand(void *ptr, u_int length, int reseed);

     u_int32_t
     arc4random(void);

     #include <sys/random.h>

     int
     read_random(void *buffer, int count);

DESCRIPTION

     The random() function will by default produce a sequence of numbers that can be duplicated by calling srandom() with '1' as the seed.  The
     srandom() function may be called with any arbitrary seed value to get slightly more unpredictable numbers.  It is important to remember that
     the random() function is entirely predictable, and is therefore not of use where knowledge of the sequence of numbers may be of benefit to an
     attacker.

     The arc4rand() function will return very good quality random numbers, slightly better suited for security-related purposes.  The random num-
     bers from arc4rand() are seeded from the entropy device if it is available.  Automatic reseeds happen after a certain timeinterval and after
     a certain number of bytes have been delivered.  A forced reseed can be forced by passing a non-zero value in the reseed argument.

     The read_random() function is used to return entropy directly from the entropy device if it has been loaded.  If the entropy device is not
     loaded, then the buffer is filled with output generated by random().  The buffer is filled with no more than count bytes.	It is advised that
     read_random() is not used; instead use arc4rand()

     All the bits generated by random(), arc4rand() and read_random() are usable.  For example, 'random()&01' will produce a random binary value.

     The arc4random() is a convenience function which calls arc4rand() to return a 32 bit pseudo-random integer.

RETURN VALUES

     The random() function uses a non-linear additive feedback random number generator employing a default table of size 31 long integers to
     return successive pseudo-random numbers in the range from 0 to (2**31)-1.	The period of this random number generator is very large, approxi-
     mately 16*((2**31)-1).

     The arc4rand() function uses the RC4 algorithm to generate successive pseudo-random bytes.  The arc4random() function uses arc4rand() to gen-
     erate pseudo-random numbers in the range from 0 to (2**32)-1.

     The read_random() function returns the number of bytes placed in buffer.

AUTHORS

     Dan Moschuk wrote arc4random().
     Mark R V Murray wrote read_random().

BSD
								September 25, 2000							       BSD