How to Prevent Multiple Votes in a PHP/MySQL Voting System: IP Addresses, Cookies, and Beyond?

Ensuring Unique Votes in a PHP/MySQL Voting System

In the design of online voting systems, safeguarding the integrity of the process is paramount. One such concern lies in preventing multiple votes from the same individual. This article explores practical approaches to implementing this requirement.

IP Address-Based Voting

One initial approach is to store individual votes in a database alongside the user's IP address. While this ensures that each user can cast only one vote, it suffers from limitations. Firstly, it can lead to a bulky database. Secondly, it precludes users with shared IP addresses, such as in office buildings or shared network environments, from voting.

Cookie-Based Voting

A simpler approach involves storing a cookie on the user's device to indicate that they have already voted. However, this method is susceptible to circumvention as users can easily disable cookies or clear their browsing data.

Considerations and Recommendations

Beyond these approaches, there are additional factors to consider:

• Unobtainably-Perfect: Using unique identifiers like government-issued numbers or passports may be overly restrictive or infeasible.
• Close-Enough-For-Reality: Registering users with email addresses or third-party authentication (e.g., Google/Facebook) provides a balance between security and convenience. Users can be limited to one vote per email address, eliminating the IP address issue.
• False Pretense: IP address-based voting may provide a false sense of security. Shared IPs and easily changed network configurations can compromise this method.
• Crash-And-Burn: Cookie-based voting is vulnerable to user manipulation and should not be relied upon as a secure means of preventing multiple votes.

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