The parties demanded that all future elections be held by paper ballot.
Despite the EC rejecting such charges, opposition parties said they didn't have faith in the current electronic devices.
They would take the EC memorandum to President Pranab Mukherjee too.
12 Apr 2017
EVM Tampering: EC's "open challenge" to hack its machines
After allegations of Electronic Voting Machines' tampering, the Election Commission threw an open challenge to hack the machines.
The multi-level challenge is open from May for a week or ten days; experts, technocrats, scientists can try and hack the EVMs.
Meanwhile, opposition parties met President Pranab Mukherjee to discuss the alleged EVM tampering during the recent elections.
A similar challenge was announced in 2009.
Mayawati, Kejriwal blame the heat on tampered EVMs
The BSP and the AAP having lost the elections alleged that the recent EVMs in assembly elections in Uttar Pradesh, Uttarakhand, Manipur, Goa and Punjab had been tampered with to BJP's favour.
09 May 2017
AAP hacks EVM, EC says it's just a prototype
AAP demonstrated a live-demonstration of how easy it is to hack the EVMs in the Delhi Assembly session.
On 10 May, it was revealed that the machine used by AAP was a mere prototype.
EC said that a prototype isn't the same as EVMs and it can be manipulated.
Moreover, the question over how the EVM was procured by the AAP were also raised.
20 May 2017
EVM challenge to begin from 3 June
The Election Commission of India (ECI) announced that the EVM hack-challenge will begin from 3 June.
Chief Election Commissioner Nasim Zaidi told the media that any national or state political party can nominate 3 people to hack the EVM.
Reiterating that the EVMs can't be tampered with, Zaidi said this was being done to preserve the "purity, integrity and credibility" of the electoral democracy.
21 May 2017
AAP decries EC's conditions in EVM hackathon
AAP has decried the conditions imposed by the Election Commission for the EVM hackathon. The party said they "request the EC to give an unconditional-access to EVMs to the political parties' nominated hackers to tamper with the EVMs."
They said the EC's conditions for the hackathon were unacceptable.
On Monday, an AAP delegation may visit the EC to seek further clarity on the matter.
27 May 2017
Only two participants in EC's hackathon, AAP out of fray
Only two parties, CPM and Sharad Pawar's NCP, have signed up for the June 3 hackathon, where they will try to demonstrate that EVMs can be tampered with.
RJD's application was disqualified as it was submitted late.
BJP, CPI and RLD have said they would like to observe the challenge. AAP and Congress, meanwhile, refused to participate, demanding an "open" challenge without any restrictions.
Why are AAP and Congress not participating?
AAP and Congress have demanded that no rules should be imposed on how parties try to hack the machines. AAP had asked for permission to change the motherboard in the EVMs, which the EC denied, saying they will no longer remain the same machine.