Author: Olaoluwa Osuntokun 2015-12-14 22:04:01
Published on: 2015-12-14T22:04:01+00:00
The author of the text has been working on designing onion routing within the Lightning Network. To find inspiration, they have turned to existing academic literature and have found two schemes that fit well into their problem domain: Sphinx and HORNET. Sphinx is a compact mixing format that achieves extremely small mix-headers by using a single group element in each header that is deterministically re-randomized by each hop in the route. The size reduction is significant, with a 20-hop mix-header weighing in at only 705 bytes. Sphinx also carries a formal proof of security, specifies replay protection, and provides sender anonymity. However, it does not provide receiver anonymity.To achieve receiver anonymity, the author turns to HORNET which sets up a duplex onion circuit between sender and receiver, allowing both sides to retain full unlinkability. HORNET requires a cumulative circuit round-trip as a setup phase, creating a level of throughput approaching 93 Gb/s. The primary addition to Sphinx's mix-header format is the Anonymous Header (AHDR).HORNET improves upon the Sphinx protocol by enabling sender and receiver unlinkability in onion routing. While Sphinx generates ephemeral keys for each hop along a path and uses them to encrypt messages at each hop, HORNET eliminates the need for per-session state storage in mix-nets by storing all session-state within the onion-packet itself. Additionally, each node only needs to maintain a local secret.To achieve sender-receiver unlinkability, modifications are necessary, which involve nested AHDRs. A working implementation of Sphinx alone is available, but a working implementation of HORNET will be released soon.
Updated on: 2023-05-18T16:39:40.593261+00:00