Passwd Command and Algorithm

movitto · 04-11-2006, 12:16 AM

Hi. Is there anyway to run the passwd command or the same algorithm that it uses and not have it write the encrypted password to the /etc/shadow file, but rather the standard output? I ask because I am want to run an application with its own independent set of users/passwords, but with the same encryption scheme that linux uses. Thanks alot.

gilead · 04-11-2006, 01:21 AM

I borrowed the following from a CVS howto years ago. IIRC it does the same thing as the passwd command. There's some info on it at http://cvsbook.red-bean.com/cvsbook.html:

Code:

#!/usr/bin/perl -w
#
# Used to generate the cvs passwd file
#

srand (time());
my $randletter = "(int (rand (26)) + (int (rand (1) + .5) % 2 ? 65 : 97))";
my $salt = sprintf ("%c%c", eval $randletter, eval $randletter);
my $plaintext = shift;
my $crypttext = crypt ($plaintext, $salt);

print "${crypttext}\n";

operator10001 · 04-11-2006, 10:12 AM

why not use xor?

CroMagnon · 04-11-2006, 03:44 PM

That script will generate encrypted passwords in the old /etc/passwd style. If you want to generate them in the /etc/shadow style, change the salt line to this:

Code:

my $salt = sprintf ("\$1\$%c%c%c%c\$", eval $randletter, eval $randletter, eval $randletter, eval $randletter);

You can have up to 8 '%c's, but each one must have a matching 'eval $randletter'.

gilead · 04-11-2006, 09:50 PM

Thanks for that, CroMagnon