Python Programming of Blockchain

was a series of three lectures given within the Graduate Course 'Blockchain and Future Society' Offered in the Fall Semester 2018 at GIST, Rep. of Korea. The instructor was Prof. Heung-No Lee. The blockchain developed in the course was not meant to be complete. Instead, aim was to understand what a blockchain, and a cryptocurrency based on it, is by doing a little bit of programming work.

To this end, Prof. Lee utilized the blog work "Learn Blockchain by Building One" of Daniel Flymen [1],[2]. Flymen's blog and his Python code offerred good introductory materials. His code was also given to learn blockchain and thus was not meant to be complete.

In my course, I have given a homework assignment to improve on his work. The code presented below was a result of homework assignment which a group of students have worked together and made improvements.

There were several upgrades made to [2]. Just to name a few notable ones, they are

1. mined blocks now have "correct" block hashes with the designated leading number of zeros. 2) A auto mining routine was included in which the mining operation is continued at a node which listens to a new block announcement and switches if a new longest chain is found.

Overall the list of functions this code can demonstrate includes: 1. Announcing transactions, 2. Including transactions into blocks, 3. Chaining blocks using Proof-of-Work(PoW), 4. Chainging the level of PoW difficulty by varying the number of leading zeros in hash values, 5. Following the consensus rule of the longest-chain-win, and 6. Interworking of peer-to-peer nodes using APIs.

The source code and the relevant lecture note are available to download here in [3],[4].

References : [1] Daniel van Flymen, "Learn Blockchain by Building One," Sept. 25th, 2017, https://hackernoon.com/learn-blockchains-by-building-one-117428612f46.
[2] Daniel van Flymen, Source code at https://github.com/dvf/blockchain/blob/master/blockchain.py. [3] Heung-No Lee, "Lecture Note on Python Programming of Blockchain," https://infonet.gist.ac.kr. [4] Heung-No Lee, Source Code of Python Programming of Blockchain, https://github.com/infonetGIST/Blockchain_lecture.