Is it possible to rig automated elections?

WATCH: Smartmatic says vote-counting machines foolproof

Metro Manila (CNN Philippines) — Social media posts of alleged poll fraud in overseas voting and local tests are casting doubt on the credibility of the elections. One of the more common allegations is that some ballot receipts show names of candidates that voters did not choose.

But poll technology provider Smartmatic said on Friday (May 6) their system is foolproof.

Can the machine credit one candidate’s vote to another?

Receipts generated by a test machine fed with test ballots were accurate. But what if the machines out in the field are programmed to cheat?

Related: Smartmatic looking into 'inconsistencies' in ballots, receipts

Miguel Avila, Pre-Sales Solutions Coordinator of Smartmatic, said it won’t happen because the software that runs the machines has gone through stringent reviews by both foreign and local experts and it passed, earning international and government certifications.

He said a hash code printed on the machines’ initialization and audit reports is the software’s fingerprint. A hash code is a unique series of letters and numbers produced by about 97,000 vote counting machines to be used in the elections. Once the software is tampered, the hash code changes. All you need to do then is compare this with the authentic hash code to determine if the software has been altered.

Memory card switching

Some observers say another way to cheat the automated polls is by switching official memory cards with ones loaded with fabricated results.

Former Biliran Rep. Glenn Chong claimed that was how he lost in the 2010 elections, but admits he has no proof to substantiate his suspicions.

"It is difficult to prove the electronic aspect of the cheating," he said.

Avila dismisses Chong’s claims. He said there is no way a vote counting machine or canvassing laptop would read a fake memory card, adding each card bears the certified software and a unique digital signature specific to the machine it is designated for. He said each machine has a main memory card and a back-up.

He said the software and the digital signature can’t be replicated in any memory card, and a fake card can’t ever work.

If you're able to get a card and program it, what program will you install there? Where will you get that program? So it is possible to get another card that's meant for another machine and insert it there. And it would have the official source code in it but not the right digital signature that's paired with the other card. So in that sense, the machine would already detect it and not read the card," Avila said.

Comelec Senior Commissioner Christian Robert Lim said there are only about six reports of voter receipt discrepancies out of over 300,00 ballots that have already been cast in overseas absentee voting.

"We can't explain it because the way the source code is crafted is that one vote for this candidate will always go to this candidate, it will never go to another candidate no?" Lim said.

But IT expert and poll reform advocate Toti Casino of the Philippine Computer Center said no matter how secure a system appears to be, there’s always a way to crack it.

At the end of the day, it is up to the voter whether to have faith in the system.