Problem - Kevin Tafuro

file, it may allocate a sizable amount of memory that remains allocated. When you’re
done generating passphrases, you should call spc_generate_cleanup( ) to close the
data file and free the memory allocated by spc_generate_passphrase( ).
void spc_generate_cleanup(void) {
if (spc_wordlist_file) fclose(spc_wordlist_file);
if (spc_wordlist_offsets) free(spc_wordlist_offsets);
spc_wordlist_file = 0;
spc_wordlist_offsets = 0;
spc_wordlist_count = 0;
spc_wordlist_shortest = 0;
}
See Also
Recipe 11.11
8.6 Testing the Strength of Passwords
Problem
You want to ensure that passwords are not easily guessable or crackable.
Solution
Use CrackLib, which is available from http://www.crypticide.org/users/alecm/.
Discussion
When users are allowed to choose their own passwords, a large number of people
will inevitably choose passwords that are relatively simple, making them either easy
to guess or easy to crack. Secure passwords are often difficult for people to remember,
so they tend to choose passwords that are easy to remember, but not very
secure. Some of the more common choices are simple words, dates, names, or some
variation of these things.
Recognizing this tendency, Alec Muffett developed a program named Crack that
takes an encrypted password from the system password file and attempts to guess—
or crack—the password. It works by trying words found in a dictionary, combinations
of the user’s login name and real name, and simple patterns and combinations
of words.
CrackLib is the core functionality of Crack, extracted into a library for the intended
purpose of including it in password-setting and -changing programs to prevent users
Testing the Strength of Passwords | 391
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