in reply to Removing similar characters

use String::Random ;
my $generator = new String::Random ;
my $invalid_pass_re = qr/(\d{3}|\w{3}|[[:punct:]]{3})/ ;
my $pass ;
do {
  $pass = $generator->randregex('.{15}') ;
} while ($pass =~ $invalid_pass_re) ;
print "$pass\n" ;

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Re^2: Removing similar characters
by Kc12349 (Monk) on Sep 01, 2011 at 19:29 UTC

    This is a slightly simpler solution than my similar code sample above. It's a good solution for shorter password lengths, but will become significantly slower as password length increases because you throw out the entire string each time it is invalid.

[reply]

      You are right, but at 15 characters it takes .02s on my hardware. I did notice that randomregex() will emit consecutive duplicates rather frequently - I didn't check to see if a new instance of String::Random in each iteration would reduce that at all (or enough to make a difference in execution time).

[reply]

        For what I'm doing, speed isn't much of an issue. However, a friend of mine is using it on a project that he's working on, so it could cause a problem there. Although, the script has been tested up to a 500 character password, so I'm trying to eliminate any restrictions which could occur with abnormally large passwords. (Not that I'd expect anyone to have the need for a 500 character password.)

[reply]

        I don't expect that another instance should change behavior. Looking at the internals of String::Random, perl's built-in rand is what is used for randomness.

        From perldoc:

        rand() is not cryptographically secure. You should not rely on it in security-sensitive situations. As of this writing, a number of third-party CPAN modules offer random number generators intended by their authors to be cryptographically secure, including: Math::Random::Secure, Math::Random::MT::Perl, and Math::TrulyRandom.

        This is maybe something the OP should take note of.

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