Access Control to BitTorrent Swarms using Closed Swarms

Dr. Njål BorchNorthern research institute,

Tromsø, Norway

Why access control?

• No access control– Limited commercial possibilities

• DRM– Control content, not distribution– Limits usability from end user perspective

• Closed swarms– Distributed access control mechanism– Differentiated services– Control network resources

DRM

• Manage restrictions on content• Favoured by Broadcast TV

– Non-authorized users costs zero– Loss of profit if people break it

• But online (unicast)?– Non-authorized user costs money– Accumulates high bandwidth cost if broken or circumvented

Control access to resources

• Central system– Authentication service– Username/password– Fairly simple solution– Accumulates bandwidth costs

• P2P system– Cost saving– Appealing scalability properties– Centralized access control on central bits– Leaking nodes

• But: Both (all really) systems can experience leaking content

Closed Swarms – the Idea

Create a flexible authentication mechanism for P2P which is both scalable and allows for experimental and innovative business models.

The nodes

AN L

The Math

The Math

The Math

So basically...

• Non-authorized nodes can be of use– They can even be explicitly allowed

• Can subsidize bandwidth to selected nodes

The basics

Proof of

AccessNode Key

Swarm

Swarm Key

Node

The Protocol

Node A- Generate and send Nonce

- Send signed PoA

- Verify PoA, allow upload

Node B

- Generate and send Nonce

- Verify PoA, allow upload- Send signed PoA

Points

• Seeds do not need to sign and send PoAs• No central access required to validate PoAs• No need to know a node's keys in advance• Only performed on connect (handshake)• BitTorrent implementation backwards compatible

– But non-CS clients are non-authorized

• Allows easy addition of seeds– Provide data or a PoA for the seedbox

Possible applications

• Sell guarantees– Free user gets community service. Might VoD, might not.– Paying customer is guaranteed high speed seeds, will VoD.

• Sell guarantees 2– Home user can watch a live event, if there is capacity– A venue can buy access to an event, and is guaranteed seeds.

• Closed group sharing– Only authorized nodes are allowed access

• Combine with Scalable video coding (SVC)– SD for free users, pay for HD