06-09-2008
Generate Random Password in C
I need a function to generate a random alphanumeric password in C code. It needs to be between 6-8 characters and follow the following rules:
Reject if same char appears # time: 4 or more
Reject if same char appears consecutively: 3 or more
I have the following random password working for numbers (0-9). I need to update it to include characters (a-z). I also need to add the validation rules above. Can someone please help me. I have been trying for days to update it but get a lot of compile errors... Thanks..
Here's what is working for number (0-9):
Random_Password()
{
int ran_int_num;
time_t seconds;
time(&seconds);
srand ((unsigned int) seconds);
/* multiply by 975 to generate a larger number */
ran_int_num = rand() * 975;
/**************************************************/
/* Need to cast the integer to character, so use sprintf */
/* %u = unsigned decimal integer %d = signed decimal integer */
/* ************************************************/
sprintf(randompw, "%u", ran_int_num);
strncpy(newpw, randompw, 8);
return(0);
}
Here's what I tried to change it to, in order to generate an alphanumeric:
GenerateRandomID()
{
char password_chars["1234567890abcdefghijklmnopqrstuvwxyz"];
int i;
int length;
char ticketid;
int random;
for (i = 0; i < length; i++) {
random = rand(0, strlen(password_chars) - 1);
ticketid = password_chars[random];
}
return ticketid;
}
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LEARN ABOUT DEBIAN
string::mkpasswd
String::MkPasswd(3pm) User Contributed Perl Documentation String::MkPasswd(3pm)
NAME
String::MkPasswd - random password generator
SYNOPSIS
use String::MkPasswd qw(mkpasswd);
print mkpasswd();
# for the masochisticly paranoid...
print mkpasswd(
-length => 27,
-minnum => 5,
-minlower => 1, # minlower is increased if necessary
-minupper => 5,
-minspecial => 5,
-distribute => 1,
);
ABSTRACT
This Perl library defines a single function, "mkpasswd()", to generate random passwords. The function is meant to be a simple way for
developers and system administrators to easily generate a relatively secure password.
DESCRIPTION
The exportable "mkpasswd()" function returns a single scalar: a random password. By default, this password is nine characters long with a
random distribution of four lower-case characters, two upper-case characters, two digits, and one non-alphanumeric character. These
parameters can be tuned by the user, as described in the "ARGUMENTS" section.
ARGUMENTS
The "mkpasswd()" function takes an optional hash of arguments.
-length
The total length of the password. The default is 9.
-minnum
The minimum number of digits that will appear in the final password. The default is 2.
-minlower
The minimum number of lower-case characters that will appear in the final password. The default is 2.
-minupper
The minimum number of upper-case characters that will appear in the final password. The default is 2.
-minspecial
The minimum number of non-alphanumeric characters that will appear in the final password. The default is 1.
-distribute
If set to a true value, password characters will be distributed between the left- and right-hand sides of the keyboard. This makes it
more difficult for an onlooker to see the password as it is typed. The default is false.
-fatal
If set to a true value, "mkpasswd()" will Carp::croak() rather than return "undef" on error. The default is false.
If -minnum, -minlower, -minupper, and -minspecial do not add up to -length, -minlower will be increased to compensate. However, if
-minnum, -minlower, -minupper, and -minspecial add up to more than -length, then "mkpasswd()" will return "undef". See the section
entitled "EXCEPTION HANDLING" for how to change this behavior.
EXCEPTION HANDLING
By default, "mkpasswd()" will return "undef" if it cannot generate a password. Some people are inclined to exception handling, so
String::MkPasswd does its best to accommodate them. If the variable $String::MkPasswd::FATAL is set to a true value, "mkpasswd()" will
Carp::croak() with an error instead of returning "undef".
EXPORT
None by default. The "mkpasswd()" method is exportable.
SEE ALSO
<http://expect.nist.gov/#examples>, mkpasswd(1)
AKNOWLEDGEMENTS
Don Libes of the National Institute of Standards and Technology, who wrote the Expect example, mkpasswd(1).
AUTHOR
Chris Grau <cgrau@cpan.org>
COPYRIGHT AND LICENSE
Copyright (C) 2003-2010 by Chris Grau
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.1 or,
at your option, any later version of Perl 5 you may have available.
perl v5.10.1 2010-10-18 String::MkPasswd(3pm)