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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pam_pwhistory

PAM_PWHISTORY(8)						 Linux-PAM Manual						  PAM_PWHISTORY(8)

NAME

       pam_pwhistory - PAM module to remember last passwords

SYNOPSIS

       pam_pwhistory.so [debug] [use_authtok] [enforce_for_root] [remember=N] [retry=N] [authtok_type=STRING]

DESCRIPTION

       This module saves the last passwords for each user in order to force password change history and keep the user from alternating between the
       same password too frequently.

       This module does not work together with kerberos. In general, it does not make much sense to use this module in conjunction with NIS or
       LDAP, since the old passwords are stored on the local machine and are not available on another machine for password history checking.

OPTIONS

       debug
	   Turns on debugging via syslog(3).

       use_authtok
	   When password changing enforce the module to use the new password provided by a previously stacked password module (this is used in the
	   example of the stacking of the pam_cracklib module documented below).

       enforce_for_root
	   If this option is set, the check is enforced for root, too.

       remember=N
	   The last N passwords for each user are saved in /etc/security/opasswd. The default is 10.

       retry=N
	   Prompt user at most N times before returning with error. The default is 1.

       authtok_type=STRING
	   See pam_get_authtok(3) for more details.

MODULE TYPES PROVIDED

       Only the password module type is provided.

RETURN VALUES

       PAM_AUTHTOK_ERR
	   No new password was entered, the user aborted password change or new password couldn't be set.

       PAM_IGNORE
	   Password history was disabled.

       PAM_MAXTRIES
	   Password was rejected too often.

       PAM_USER_UNKNOWN
	   User is not known to system.

EXAMPLES

       An example password section would be:

	   #%PAM-1.0
	   password	required       pam_pwhistory.so
	   password	required       pam_unix.so	  use_authtok

       In combination with pam_cracklib:

	   #%PAM-1.0
	   password	required       pam_cracklib.so	  retry=3
	   password	required       pam_pwhistory.so   use_authtok
	   password	required       pam_unix.so	  use_authtok

FILES

       /etc/security/opasswd
	   File with password history

SEE ALSO

       pam.conf(5), pam.d(5), pam(8) pam_get_authtok(3)

AUTHOR

       pam_pwhistory was written by Thorsten Kukuk <kukuk@thkukuk.de>

Linux-PAM Manual						    06/04/2011							  PAM_PWHISTORY(8)