VVS, Visitor Verification Script for web forms
Displays an ascii art image of a random sequence of letters/digits and asks the visitor to type the sequence in a field provided. If the typed sequence is the same as in the image, the original form script (action) is invoked. Otherwise, the visitor is asked to go back and correct what he/she typed before. VVS requires Perl with the CGI class. It works for any form script written in Perl, independently of whether the script uses CGI or cgi-lib.pl or etc. It also preserves values of arbitrary variables of the environment for use in the original form script.