The Anonymous File Transfer Network

(AFTN)

Jared Rose 1/11https://sourceforge.net/projects/aftn/

A system for sending files anonymously

Uses RSA & digital signatures for establishing a user’s “identity”

Utilizes the Tor network◦ SSL Encryption◦ Onion Routing◦ Hidden Services

Cross platform compatible

Jared Rose 2/11

What is AFTN?

Users of the AFTN are anonymous

Clients can verify the “identities” of other clients and servers

File integrity/validity can be checked◦ MD5 hashing + file size

Synchronization of contact information between clients and servers

Jared Rose 3/11

Goals of AFTN

Files are protected by end-to-end encryption◦ Tor + Hidden Services

Secure updating and management of encryption/signing keys on the server

Allow clients to anonymously retrieve key and address information from servers

Jared Rose 4/11

Goals of AFTN (Continued)

Digital privacy concerns

“Big Government”

Whistle blowers

Censorship

Humanitarian work

Its interesting

Jared Rose 5/11

Why Create AFTN?

Potential for illegal use◦ IP infringement◦ Crime◦ Malicious software/Spam

Encryption export laws◦ Open source

Jared Rose 6/11

Ethical/Legal Concerns

Two types of hosts:◦ Clients◦ Directory Servers

Nodes connected to Tor network◦ Outbound connections through Vidalia◦ Inbound connections to server sockets listening at a

Tor hidden services address◦ Provides anonymous exchanges between hosts◦ End to end encryption

Jared Rose 7/11

How does AFTN work?

Clients register with a directory server

Directory servers supply contact info for clients

Clients send files to other clients (P2P)

Clients know servers contact info through white lists◦ Clients of non-whitelisted servers ignored◦ Permits organizations to be “off the grid”

Jared Rose 8/11

Clients & Directory Servers

Provides anonymity through onion routing

Hidden Services:◦ NAT/Firewall traversal◦ End to end encryption◦ Hides server locations

Bandwidth/Speed are issues◦ Onion routing is bandwidth intensive◦ Speed influence by the types of node you traverse

Jared Rose 9/11

Tor

Q. If anonymous, how do we know we are talking to the right person?◦ A. Public Key Cryptography!◦ Public/Private signing key

Jared Rose 10/11

Anonymity and User Identity

When clients register with a server:◦ Create unique name/server pair answer

(name#server)

◦ Register public “master” key used for signing other keys

◦ Any changes to keys/information on server must be signed w/ master key

Master key can be stored separate from the rest of the system for security

Jared Rose 11/11

Anonymity and User Identity

Jared Rose 12/11

Where are we at Right Now?