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47 lines
2.1 KiB
Markdown
47 lines
2.1 KiB
Markdown
# High-Level Architecture
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## Path Building
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<p align="center">
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<img src="/docs/lokinet_pathbuild_no_steps.png">
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</p>
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Starting from the top, here's a high-level overview of how the lokinet client builds a path to a terminating node
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1. Client semi-randomly selects SN's for hops 2 and 3 using Introset Hash Ring (IHR)
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- First hop is sticky: upon initialization of lokinet, 4-5 first hops are selected
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2. Message sent to hop 1
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- Message consists of eight records in a linked list. Four hops are typically used, leaving the last 4 links as dummy records
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- Each record contains a TX (upstream) path ID and RX (downstream) path ID
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- Each record has a pointer to the next record, except for the final hops' record; the pointer here is recursive, signalling the end of the path-build
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3. Hop 2 pops top record, appends metadata, and pushes record to the back of linked list
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- Hop adds metadata to the record, such as optional lifetime, pubkey to derive shared secret, etc
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4. Steps 2-3 are repeated for the remaining hops until destination is reached
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- Final hop reads the recursive pointer signalling the end of the path-build process
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5. Upon completion, plain-text reply is propagated backwards, where the client can then decrypt all records
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6. Client measures latency
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- A) Routing message is sequentially encrypted using hop 4's key through hop 1's key
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- At each iteration, the nonce is permuted by XOR'ing the previous nonce with the hash of the secret key of each hop
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- B) Routing message is sent s.t. each hop can decrypt, with final hop receiving plain-text
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- Each hop appends latency and expiration time data, with the final hop interpreting the plain-text as a routing message and sending it back to the client
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7. Introset is published to IHR upon successful completion; introset contains:
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- Path ID's of routers
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- Latency and expiration time for each hop
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- DNS SRV records
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- etc
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### Failure Cases
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1. Next hop is an invalid SN
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2. Cannot connect to SN
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In either case, the path-build status is sent backwards with an error flag. Once received by the client, metadata related to the prospective path is wiped and the path forgotten
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