TIMTOWTDI

1. chomp the password string
2. Get the length of the copy of the password string and compare it to the minimum and maximum allowed length: if it is out-of-bounds, reject the password; otherwise
3. Make a copy of the password string
4. Delete all illegal characters in the copy of the password string:  tr/a-zA-Z0-9//d
5. Compare the original and the copy of the password string: if they are different: reject the password string; otherwise
6. untaint the password string

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law