In this chapter we will describe the Lightning Network's _Onion Routing_ mechanism. The invention of _onion routing_ precedes the Lightning Network by 25 years! Onion routing was invented by U.S. Navy researchers as a communications security protocol. Onion routing is most famously used by _Tor_, the onion routed internet overlay that allows researchers, activists, intelligence agents and everyone else to use the internet privately and anonymously.
In this chapter we will describe the Lightning Network's onion routing_ mechanism. The invention of _onion routing_ precedes the Lightning Network by 25 years! Onion routing was invented by U.S. Navy researchers as a communications security protocol. Onion routing is most famously used by Tor, the onion routed internet overlay that allows researchers, activists, intelligence agents, and everyone else to use the internet privately and anonymously.
In this chapter we are focusing on the "Source based Onion Routing (SPHINX)" part of the Lightning protocol architecture, highlighted by a double outline in the center (Routing Layer) of <<LN_protocol_onion_highlight>>:
In this chapter we are focusing on the "Source-Based Onion Routing (SPHINX)" part of the Lightning protocol architecture, highlighted by a double outline in the center (Routing Layer) of <<LN_protocol_onion_highlight>>.
[[LN_protocol_onion_highlight]]
.The Lightning Network Protocol Suite
@ -13,9 +13,9 @@ Onion routing describes a method of encrypted communication where a message send
Each of the intermediary nodes can only "peel" one layer and see who is next in the communications path. Onion routing ensures that no one except the sender knows the destination or length of the communication path. Each intermediary only knows the previous and next hop.
The Lightning Network uses an implementation of onion routing protocol based on _Sphinx_footnote:[http://www0.cs.ucl.ac.uk/staff/G.Danezis/papers/sphinx-eprint.pdf[George Danezis and Ian Goldberg. Sphinx: A compact and provably secure mix format. In IEEE Symposium on Security and Privacy, pp 269–282. IEEE, 2009.]] developed in 2009 by George Danezis and Ian Goldberg.
The Lightning Network uses an implementation of onion routing protocol based on _Sphinx_ footnote:[George Danezis and Ian Goldberg, "Sphinx: A Compact and Provably Secure Mix Format," in IEEE Symposium on Security and Privacy (New York: IEEE, 2009), 269–282.]] developed in 2009 by George Danezis and Ian Goldberg.
The implementation of onion routing in the Lightning Network is defined in https://github.com/lightningnetwork/lightning-rfc/blob/master/04-onion-routing.md[BOLT #4-Onion Routing Protocol]
The implementation of onion routing in the Lightning Network is defined in https://github.com/lightningnetwork/lightning-rfc/blob/master/04-onion-routing.md[BOLT #4-Onion Routing Protocol]
=== A Physical Example Illustrating Onion Routing
@ -32,7 +32,7 @@ The Lightning Network uses _source routing_, which means that the payment path i
There may be many paths that make it possible for Alice to reach Dina. We will explain the process of selecting the _optimum_ path in <<path_finding>>. For now, we'll assume that the path selected by Alice uses Bob and Chan as intermediaries to get to Dina.
====
As a reminder, the path selected by Alice is shown in <<alice_dina_path>>, below:
As a reminder, the path selected by Alice is shown in <<alice_dina_path>>, below.
[[alice_dina_path]]
.Path: Alice to Bob to Chan to Dina
@ -43,7 +43,7 @@ Let's see how Alice can use this path without revealing information to intermedi
.Source-based routing
****
Source-based routing is not how packets are typically routed on the internet today, though source routing was possible in the early days.
Internet routing is based on _packet switching_ at each intermediary routing node. An IPv4 packet, for example, includes the sender and recipient's IP address and every other IP routing node decides how to forward each packet towards the destination.
Internet routing is based on _packet switching_ at each intermediary routing node. An IPv4 packet, for example, includes the sender, and recipient's IP address, and every other IP routing node decides how to forward each packet toward the destination.
However, the lack of privacy in such a routing mechanism, where every intermediary node sees the sender and recipient, make this a poor choice for use in a payment network.
nranjalkar
3 years ago