6° of Darkness

or

Using Webs of Trust to

Solve

the Problem of Global

Indexes

The problem

● Most P2P networks are insecure● Thus they are susceptible to lawsuits

Napster

● Centralized servers● Easily taken down

Gnutella

● Decentralized● Still possible to glean IP addresses of the

individual nodes

KaZaA

● Much more efficient● Uses supernodes to route traffic● Hundred of users have been sued

Direct Connect

● Uses hubs and has large minimum share sizes

Bittorrent

● Each file must be hosted by a tracker and then is forwarded though a chain of downloaders/uploaders

Bittorrent

● If the tracker goes down, the other nodes have no way of finding each other

● The IP address of the tracker is easily traced

WASTE

● A truly secure network with rings of encryption

WASTE

● The problem is that these two networks cannot communicate with each other

WASTE

● The reason why other P2P networks are so popular is because you can share files with people you don't personally know

A New Network

● What is needed is a network that will allow you to share files with people you don't know, without revealing your identity to them.

A little history

● In 1967 Stanly Milgrim published an article entitled “The Small World Phenomenon” in Psychology Today

A little history

● In 1967 Stanly Milgrim published an article entitled “The Small World Phenomenon” in Psychology Today

● He concluded that most people in the world were connected to each other by a chain of six friends

A little history

● In 1967 Stanly Milgrim published an article entitled “The Small World Phenomenon” in Psychology Today

● He concluded that most people in the world were connected to each other by a chain of six friends

● It was from this and later studies that the popular idea of Six Degrees of separation came from

A little history

● There has been some debate about whether the average of six connections between any two people holds true throughout the world, but physiologists agree that are a lot of subnetworks with people being connected by an average of six or even fewer friends

Six Degrees

● It may be possible to create a secure anonymous network on this principle

Six Degrees

● Instead of sharing files with anyone who asks for them you will only reveal what files you are sharing to your trusted friends

Six Degrees

● In turn they will let others know about these files, but not reveal your IP address

So How does this Work?

● The base of the network is similar to WASTE, and the entire protocol depends on Public Key Cryptography

Public Key Cryptography

● Each connection in this darknet represents an exchange of public keys

BA

Here is my public Key

Public Key Cryptography

● If Bob put Alice's public key in his list of trusted users (Bob has decided to trust Alice), Alice will be able to download files from Bob

BA

Bob: I'll trust this key

Public Key Cryptography

● All the files Bob send to Alice will be encrypted with Alice's public key, and no one will be able to read them but Alice.

BA

I can't read this!

E

Public Key Cryptography

● Assuming that Alice is kind enough to return the favor and trust Bob, they will both be able to access each other's files, and Eve will not be able to eavesdrop at all.

BA

I still can't read this!

E

Public Key Cryptography

● Supposing that Carol has a file that Alice wants.

BA

E

C

Public Key Cryptography

● Alice does not trust Carol, more importantly Carol does not trust Alice, so there is no way for Alice to know that Carol has the file

BA

E

C

Public Key Cryptography

● If Carol trusts Bob, she will tell him what files she has, and in turn, Bob can tell Alice

BA

E

C

Public Key Cryptography

● Alice will then request the file from Bob, and Bob will request the file from Carol

BA

E

C

Public Key Cryptography

● Bob will act as proxy between Carol and Alice, so that Carol does not have to reveal her IP address to Alice

BA

E

C

Public Key Cryptography

● All the while, Eve who had been trying to eavesdrop on this transfer, can read none of the file.

BA

E

C

Six Degrees

● This method can scale to many users each who only trust a few people, yet can access the entire network

G

B

E

F

H

A

I

C D

Six Degrees

● Of course the more people you trust (more correctly the more people you can convince to trust you) the faster your downloads will be.

G

B

E

F

H

A

I

C D

G

B

E

F

H

A

I

C D

Problems

● If Bob is the only link between a lot of people, file transfers between them will be very slow

G

B

E

F

H

A

I

C D

Problems

● Bob can help solve this problem by convincing more of his friends to trust each other

G

B

E

F

H

A

I

C D

G

B

E

F

H

A

I

C D