A minimal viable blockchain
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DavidM-D and sdiehl Separated out the nonce check and added validation for proof of work (#3
)

Previously if you just picked a random nonce (1 for example) isValidBlock
would return nothing as it didn't check whether proof of work had been run
Latest commit 7d7ee67 Jun 9, 2018

README.md

Nanochain

A minimal viable blockchain to demonstrate simple blockchain principles.

Project goals:

  • Well-documented.
  • Low-line count.
  • Low-dependencies.
  • Using classic proof-of-work.
  • Basic P2P using UDP chatter.
  • Supports chain reconfiguration.
  • No encryption or accounts.
  • In-memory.

Enabling Multicast

Nanochain uses a UDP multicast gossip protocol for P2P networking. Before running the program, make sure your localhost network interface has multicast enabled. The simplest way to do this on Unix-like systems is:

$ sudo ifconfig lo multicast

Otherwise, the program with fail with addMembership: failed (Unknown error -1) error from the Multicast module when attempting to add the node to the multicast group.

Usually, lo is the name of the local loopback (localhost) network interface on modern Linux machines, but could differ depending on your machine and/or OS. To check what your localhost network interface is, type ifconfig; The interface prefixed by lo, e.g. lo0 is usually the interface of interest. Simply replace lo with the name of your localhost network interface in the command above.

Running the Demo

Install the Stack build system:

$ stack setup
$ stack build
$ stack exec nanochain

Ports 3000, 3001, and 3002 are opened for the initial nodes. In the browser go to:

localhost:3000/blocks

To mine blocks query:

localhost:3001/mineBlock

To see the current chain query:

localhost:3000/blocks

To add a new peer, use the addPeer endpoint followed by any open port:

localhost:3000/addPeer/3003

to add localhost:3003 as a peer.

Consensus (Proof Of Work)

Nanochain uses a simple proof of work (PoW) approach to chain concensus: To mine a block on the chain, a node must compute a nonce such that that resulting hash of the block being mined begins with a number of 0's equal to round(ln(n)) where n is the length of the current chain. For this PoW implementation the average nonce computed is 16^n, so when the length of the chain surpasses 12 (round(ln(n)) == 4) it begins to take several seconds to mine each block. As n surpasses 23, mining a block could take well over 10 minutes.

License

Copyright 2017 Adjoint Inc

Released under Apache 2.0.