This purported "open challenge" is an response to the current political drama staged by the opposition parties crying foul over lost elections.
In UP, the current ruling party sweeped with a thumping majority. (325/403)
But, the same Congress and AAP that were defeated to nil in UP, got significant and in fact leading number of seats in Punjab - 77/117 and went on to form the government. AAP got to form the Govt in Delhi in the last elections.
In Manipur and Goa - Congress got 28 and 17 respectively and was the single largest party. It is another story that they were not able to muster enough strength to form the government. [1]
So, basically, they cry foul in UP accusing the machines were rigged. But, they happily accept the same machines' verdict in Punjab and form the govt and conveniently ignore the fact that in two other states the same machines gave them the single largest party status.
What election commission is trying to do is to prove their parity across parties, which you can see from the above results. Election Commission is an independent body in India and cannot be influenced or rigged towards one or other party of which the opposition is accusing them of unfairly.
Having said that, yes, any system is hackable may be, people can try. But, hey, at least EC is open about it and cannot be accused of favouring any one entity. It can be thought of as a hackathon and if someone finds a bug, they will fix it.