A pro-electoral reform demonstrator delivers a speech via a live-streaming device as several dozen anti-lockdown activists take part in a rally in Melbourne on September 15, 2015. Photo: Dean Sewell

Anti-lockdown protesters have used encryption to avoid detection during rallies in Melbourne.

They broke through security and targeted the door of the Federal Electoral Commission, but the material was found on a nearby carport.

Ongoing investigations by the Victorian Criminal Intelligence Commission and Victoria Police found the activists infiltrated Federal Electoral Commission staff, but protected the material.

The Melbourne Project is an anti-lockdown legal action group, known for staging road blocks in Melbourne intersections for the past year, using relay teams to negotiate deliveries of resources in exchange for accommodation, food and other refuge.

​Members of the group used an encrypted messenger app, Signal, and a teleconferencing network, Discord, and internet cafes to receive and respond to every message the police and Immigration Minister Peter Dutton sent about their protests.

Organisers on the Melbourne Project website have named Hamilton, 64, a retired magistrate from Melton, the author of Sunday Night.

The site describes Hamilton as a “law-abiding taxpayer and resident of Melbourne in good standing for many years” who had been a “quiet volunteer lawyer” at the Equality Council and a member of St Augustine’s Church, which is the only religious institution in Melton.

It also describes him as a “revered former officer of the Melbourne Police, and Australian Navy veteran”, but gives no further details.

The phone line has been sold to multiple organisations.

Police spent days combing through the app, hoping to determine who is behind the activity. During a raid in Melbourne on Monday, officers seized a server and computers used to store classified information and other data.

It is not yet known whether all or some of the data is in the possession of the authorities.

The IP address used to forward the messages has been named as an IP address belonging to Hamilton. The next step in the investigation is for authorities to test the servers to see if a person has been inside for a period of time to make sure the messages are legitimate.

Victoria Police defended its handling of the technology, saying the communiqués were able to be encrypted thanks to advances in cryptography and their peer-to-peer communication capabilities.

“The alert came through via the encrypted messaging services Wickr and Shadowfax at roughly 8pm AEDT on Saturday night,” Victoria Police said in a statement.

“Within hours, an investigation team was on the ground and at 6.30am Sunday morning that this was the most significant breach of the operation.”

The Victorian Civil and Administrative Tribunal, which oversees policing across Victoria, received the case on Friday, saying it had found the calls for rallies to proceed despite the breach.

Victoria Police used a similar tactic during Sunday’s demonstrations, but the destruction of an official emblem was overturned on appeal.

Police said at the time they used fake flags and had help from others to disguise them.

The national head of the Australian Police Association, Neil Gaughan, said security forces cannot access the speaker phones, but had the ability to see the door, and a detective told the tribunal during the raids that “all around the group there were people pretending to be terrorists”.