10-02-2012, 04:38 PM
Towards an Analysis of Onion Routing Security
onion.ppt (Size: 424 KB / Downloads: 60)
Onion Routing
Onion router ≈ real time Chaum mix
Store and forward with minimal delays
Onion routing connection phases
Setup
Transmission
Teardown
Setup Phase
Connection initiator builds an onion
Layered cryptographic structure, specifying:
Path through network
Point-to-point symmetric encryption algorithms
Cryptographic keys
Structure not rigorously specified in paper
At each step
Router decrypts entire structure
Sets up encrypted channels to predecessor and successor nodes
Forwards new onion on to successor
Transmission Phase
When connection initiator wants to send data
Break data into uniform (128 bit) blocks
Encrypt each block once for each router in the path
Note: Use symmetric encryption here
Send data to first onion router
All onion routers connected by persistent TCP thick pipes which add another layer of encryption on top of all of this encryption