Last week, a padded envelope was delivered to the Kunst Halle St Gallen, a contemporary art gallery in St Gallen, the city known as the gateway to the Swiss Alps.

The envelope contained a DVD case, which held a vacuum-sealed aluminium foil packet. Inside the packet was a transparent plastic pouch containing 10 yellow tablets stamped with the Twitter logo, a fluttering bird.

The tablets were 'Yellow Twitter' ecstasy pills purportedly made of pure MDMA, the acronym for the compound's chemical name.

The pills were ordered by a shopping bot that paid in bitcoin. It was written by the art group !Mediengruppe Bitnik, called Random Darknet Shopper, that's part of an installation at the gallery.

The pills were added to the installation, where they joined a carton of contraband cigarettes from Moldova and a set of 'masterkeys' that promised to unlock communal gates and storage areas in the United Kingdom.

Random Darknet Shopper is part of an exhibition at the gallery that examines the dark web called, 'The Darknet - From Memes to Onionland. An Exploration'.

Carmen Weisskopf, a co-founder of the art group, told CoinDesk:

Random Darknet Shopper has four weeks left to run. It has already purchased eight items off Agora, which it selects randomly, and which have to fit into its weekly $100 bitcoin budget. The bot is programmed to buy one item each week, which it usually does on a Wednesday, Weisskopf said.

According to Weisskopf's co-founder, Domagoj Smoljo, the bot is written in Python and is completely automated, with the exception of the human assistance that is required to enter Captcha information that is prompted by Agora upon login.

Obtaining bitcoin – the de facto currency of the darknet markets – has become increasingly easy for the project to do since the group began experimenting with the idea, Smoljo said.

He explained:

As the installation entered its seventh week at the gallery, it got an unexpected boost in public attention from Operation Onymous, the inter-continental crackdown on illicit darknet markets that saw the seizure of dozens of hidden sites, including Silk Road 2.0.

"We've had a few newspapers write about the installation ... they focused on the drugs because it's the item that could be seen as illegal. We really don't know what's going to happen now," Weisskopf said.

Smoljo said their group had consulted a lawyer before the installation opened to examine the legal and ethical quandaries the installation could provoke. For example, Smoljo said, gallery staff might be required to retrieve deliveries from the post office, putting them at risk of being in possession of illicit drugs.

"Our lawyer said there is a sort of higher [public] interest reason for arts experiments. Because it is a reality, and I think the arts have a very specific duty to show reality," he said.

The group makes no attempt to hide its identity on the dark markets. Its bot is named 'randomdarknetshopper' and its profile contains a link to information about the installation.

The group's work is inspired by the Mail Art movement of the 1950s and 60s, where artists like Ray Johnson tried to circumvent the commercial exploitation of their work using photocopied images, postcards and a variety of other media, according to the Grove Encyclopaedia of American Art.

A previous piece by the group, called 'system_test', consisted of a videocamera that was mailed to Wikileaks founder Julian Assange at the Ecuadorian embassy in London. The camera broadcast its movement through the postal system live on the Internet.

"We used the same methods with this piece. The mail aspect is a lot more tactical. Mail systems still have something called 'postal secrecy' ... we realised that you do not have 'postal secrecy' online," Weisskopf said.

Images via Kunst Halle Sankt Gallen, Gunnar Meier, !Mediengruppe Bitnik