hidden services, zero knowledge

Class 20:Hidden Services,Zero Knowledge

Cryptocurrency Cabalcs4501 Fall 2015

David Evans and Samee ZahurUniversity of Virginia

2

Plan for Today

Hidden Services using Tor

Zero Knowledge (today and next Weds)

Monday’s class:

PS3 is Due Sunday, 8:29pmOffice Hours: After class today: Samee (Rice 442) Thursday, 2:30-3:30: Dave (Rice 507)

3

What’s going on!???!?

August 26, 2015BTC: $225

4

(Day before class started)

5

(Day before class started)

6

(Day before class started)

7

Why the big increase?

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9

10

Anonymous Communication

Client Server

Node A

Node B

Node C

11

12

Generate key pair

private public

address = first 10 bytes of H(public)

silkroadvb5piz3r.onionfacebookcorewwwi.onion

13

Generate key pair

private public

address = first 10 bytes of H(public)

silkroadvb5piz3r.onionfacebookcorewwwi.onion

14

Hidden Server

Introduction Point (Tor Relay)

Tor LinkDirectory Service

Client

1

2

3

15

Hidden Server

Introduction Point (Tor Relay)

Tor LinkDirectory Service

Client

1

2

3

Rendezvous Point(selected by Client) 4

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Hidden Server

Introduction Point (Tor Relay)

Tor LinkDirectory Service

Client

1

2

3

Rendezvous Point(selected by Client) 4

5

17

Hidden Server

Introduction Point (Tor Relay)

Tor LinkDirectory Service

Client

1

2

3

Rendezvous Point(selected by Client) 4

56

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Hidden Server

Introduction Point (Tor Relay)

Tor LinkDirectory Service

Client

1

2

3

Rendezvous Point(selected by Client)

4

56

channel between client and server,both only learn Rendezvous Point IP

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IEEE Security and Privacy 2006

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How did the FBI find the Silk Road Server?

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Architecture of Silk Road

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Back end server configuration:(released by FBI)

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Ross Ulbrict’s sentencing letter

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https://blockchain.info/address/1F1tAaz5x1HUXrCNLbtMDqcw6o5GNn4xqX

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https://blockchain.info/address/1F1tAaz5x1HUXrCNLbtMDqcw6o5GNn4xqX

Tim Draper (VC) ~$19M?

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Exhibit B Life in Prison

78 months

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Zero Knowledge

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ChargeProblem Set 3 due SundayUpcoming office hours:

Now: 3:30-4:30pm (Samee, Rice 442)Thursday: 2:30-3:30pm (Dave, Rice 507)