Playing Card Based Routing Protocols

Participatory Installation, Playing Cards, Crowd, Limehouse Town Hall, 14.11.03 — 29.11.06


A label with following information is printed and stuck on the face of a standard playing card.


1. if this message is for you, read it. stop.
2. if you know the recipient, give them this card. stop.
3. if you don’t know the recipient, give this card to someone else. stop.

Users fill in the cards with messages using the fields provided, and then pass the card on to a second person. The second person follows the instructions using the routing protocol provided, leading to the messages successful delivery.


The Playing Card Based Routing Protocol is a messaging protocol that uses playing cards as the physical layer of the network.

In the same way as the Internet is imagined as a civilian repurposing of the military funded Arpanet network, the card based routing protocol is a repurposing of the US military Deck of Doom. This was recently deployed in the 2003 Iraq Invasion as a means for soldiers to remember key faces in the Iraqi high command. In this new version while the physical layer is essentially the same (the standard 52 card deck), the goal of the information transfer is communication with the recipient rather than termination.

The system is comprised of two main parts:

Messaging Protocol.

The messaging protocol is RFC2822 compliant so that the messages are valid Internet mail messages (emails).

The required fields of the RFC are the From: and Date: fields. The To: field is not required but makes delivery of the message much more likely.

Routing protocol.

The routing protocol is based on a very simple algorithm.

1. if this message is for you, read it. stop.
2. if you know the recipient give them this card. stop.
3. if you don’t know the recipient, give this card to someone else. stop.

This is based on one of the simplest routing protocols implemented in packet networks like the Internet.


The protocol has the advantage of operating in areas where there is no other existing telecommunications infrastructure, making it highly suitable for the developing world. In the developed world the protocol has the advantage of being immune to both electronic surveillance and in contrast to the internet does not yet have a connection logging requirement. In some juristictions the protocol may however come under gaming laws though the lack of charging in the network make it hopefully compliant with many gambling regulations.


Tomas Krag in his book “Optimising Playing Card Based Routing Protocols” mentions that the order of playing cards sent can also be used to sequence packets for longer messages. A message maybe split across a sequence of cards and reconstructed on delivery, even though individual packets have taken different paths. In these cases suit and card ranking obviously becomes important and as there is no international standard additional protocols should be added (perhaps in the margin?) There are some pre-existing protocols based on game that maybe of help here such as the Phillipino pusoy dos protocol (diamonds, hearts, spades, clubs) or the more familiar contract bridge (spades, hearts, diamonds, clubs)


There have been 4 implementations of the Protocol, one at the Next Five Minutes event in Amsterdam, the second at in Berlin over the same weekend ( 11->14.09.2003), the next at DMZ in London (11->14.11.2003) and the most recent in Dharamsala India (16-20.11.2007)

The first successful message delivery of the Berlin Implementation took place at 1400 between Julian Priest and Armin Medosch using the 8 of spades carrier (which corresponds to the tariq aziz card).

The Berlin Implementation

The Berlin Implementation used 8 packs of standard 83x52mm plastic coated playing cards manufactured by Sundhi Games and Sports of India and purchased on the Rostock Ferry (2 Euros per pack). The cards are intersting in that they have 3 jokers making a total message stack of 55 cards.

  • The labels were bought in Alexander Platz Berlin and are standard Avery 3490 70x36mm Inkjet/Laser labels
  • The label text was laid out using the label system built into the OpenOffice suite
  • The OpenOffice label template is available for download here.
  • The labels were printed on 25 sheets using an HP Deskjet 1100 printer.
  • The labels were applied to the cards by 8 volunteers at the freifunk summer convention during a morning network outage.
  • When the network is down – build your own.
  • Total Labels – 600
  • Total Cards – 440


  • 8 packs playing cards – 16 Euros
  • 1 pack labels – 10 Euros

Many have commented that as the card makes use of the existing human social and transportational networks, the card based network at 26 Euros for 6 billion potential nodes is better value than either UMTS, 802.11 or indeed any other machine based network. It should be noted that the network coverage only extends to poulated regions.

The Amsterdam Implementation

The Amsterdam Implementatation was presented by Gini Simpson and Marina Vishmidt using printed index cards.

The London Implementation

The London Implementatation was presented at the DMZ media arts festival – a two-day event held in Limehouse Town Hall, East London on the 14th and 15th November 2003.

5 packs of Lucky Brand plastic playing cards were purchased at a local Limehouse newsagent, and stickers were applied by volunteers in the Limehouse Map Room.

A presentation on the routing protocol was given and hundreds of messages were routed throughout the 2 day event. There was a noticeable increase in spam sent through the system which reflected non-judgemental routing, the commercial culture of London and the interests of the participants. “Unblock your Drains” was one example.

Presentation notes

  • New messaging protocol.
  • Based on outdated military protocol the Deck of Doom
  • Swords to ploughshares
  • Deck of Doom death of recipient
  • Physical mesaging network
  • The same tradition as the Internet
  • 2 parts
  • Message at the top
  • RFC2822 compliant email
  • Routing protocol at the bottom
  • Low installation cost around 1.50 GBP for 52 messages
  • Significantly cheaper than an sms
  • Reaches those without mobile phones around 3p per message
  • Truly global coverage implementation of a 6 billion node network
  • Uses existing transport infrastructure
  • Intelligent routing
  • For more information see Tomas Krag’s landmark text Optimising Playing Card Based Routing Protocols
  • Please feel free to use the cards

The Dharamsala Implementation

A version of the protocol was operated at Wsfii.Dharamsala in Dharamsala India in November 2006 by Fred Pook using business cards which were printed locally instead of playing cards.


Routing in Mesh Networks