MuON: Epidemic Based Mutual Anonymity

Neelesh Bansod, Ashish Malgi, Byung Choi and Jean Mayo

Introduction: P2P Networks

Peer to peer networks Peers cooperate to achieve each others goals

Peers contribute and share resources Focus on unstructured P2P networks

Completely distributed

Introduction: P2P Networks

Characteristics of P2P networks Large sizes Untrusted participants

End-hosts cannot be trusted Churn

Continual changes in system membership/topology Rate of change (churn) varies with applications

Challenges for anonymous communication Latency, reliability, resource consumption and anonymity

need to scale with increasing churn and size.

Anonymity

Anonymity Identities on Internet are not hidden Hide the participant identities and communication

Type of anonymity guarantees

Initiator anonymity Responder anonymity Mutual anonymity

Anonymity Approaches

Anonymity by random path forwarding

I

C

A

D

B

R

Message loss Current node leaves the network Increasing churn causes increasing losses

Anonymity Approaches

Anonymity by creating routes

I

C

A

D

B

R

Creates anonymous routing to forward messages Node on path leaves the network

Anonymous path breaks Path needs to be detected and reconstructed

Increasing churn causes increasing losses

Anonymity Approaches

Anonymity by group communication

I

CA

D

BR

Suitable for networks with churn Needs multicasting primitive

Scalable, reliable and bounded latency Large groups

high overhead high anonymity

MuON: Basic idea

Public key is used to identify recipient

Small header created for each message Header is encrypted using public key of recipient Message and header have suitable encryption,

checksums and nonce for confidentiality and integrity. Non-encrypted field in header called owner

IP of node (or owner) with message

MuON: Basic idea

Header is multicast to all members Use an epidemic protocol for multicasting

Reliable delivery to all members Bounded latency in large groups

Larger message sent to subgroup Dynamically created subgroups

For a given header, a peer pulls the corresponding message from the owner with probability P inter

intermediate probability Node becomes the new owner

If a node can decrypt the header, it pulls the message Reliable delivery at recipient

MuON: Basic idea

X

B

A

C

R

HDR_X

HDR_X

MuON: Basic idea

X

B

C

R

HDR_XHDR_X

A

MuON: Basic idea

X

B

C

R

HDR_X

HDR_AHDR_A

HDR_X

A

MuON: Basic idea

X

B

A

C

R

HDR_A

HDR_C

HDR_A

HDR_X

HDR_C

MuON: Basic idea

X

B

A

C

R

HDR_X

HDR_B

HDR_X

HDR_B

HDR_C

HDR_B

MuON: Basic idea

X

B

A

C

R

HDR_C

HDR_BHDR_A

MuON: Reliability

MuON: Latency

MuON: Bandwidth consumption

MuON: AnonymityPinter= 0.1 Pinter= 0.3

Pinter= 0.5 Pinter= 0.8

Conclusion

Churn in P2P provides interesting challenges Epidemic protocols provide a solution MuON provides reliable anonymous

communication with interesting properties Future work

Further improve anonymity of MuON Cannot withstand global adversary

Investigate use in different applications like service availability

MuON: Message format

Sending message from I to S MSG={r1, id, data}ksession

Data encrypted with ksession for confidentiality

Contains nonce r1 and identifier for integrity

Profile (hdr)={r1, ksession, kI+,{H(D)} kI

-} kS+

D={r1, ksession, kI+,MSG}

Message identifier is H(hdr)

Anonymity Guarantees

Local eavesdropper Withstands attack

Collusion attack Withstands unless all nodes are malicious

Timing attack Withstands unless global adversary

Traceback attack Withstands unless global adversary

Predecessor attack Withstands attack

Intersection attack Withstands unless global adversary

Message volume attack Withstands unless global adversary

Simulation Model of P2P

r: Single run of protocol (150 above) d: Network churn Average session time: 1 + 10(1-d) (r -1)

Reliability

Reliability

Latency

Latency

Header overhead

Header overhead

Data overhead

Data overhead