Add bitcoin

[lucasleecr]

Link to the codebase

https://github.com/bitcoin/bitcoin/

Which release/version did you read?

0.1.5. (https://github.com/bitcoin/bitcoin/releases/tag/v0.1.5)

Why it is a good project to read?

• Written by Satoshi Nakamoto!
• First implementation of blockchain. A lot of cryptocurrencies are forked from it.
• Concise - only 9k lines of source files and 6k lines of header files.
• Most of the code is still relevant today.

Starting point

ui.cpp (https://github.com/bitcoin/bitcoin/blob/v0.1.5/ui.cpp). This is where the initialization happens when a bitcoin application starts.

Reading order

• Bitcoin address
• Transaction
• Mining
• P2P network
• Blockchain and consensus

Interesting parts

Almost everything. It was an innovation.

Any parts should be skipped?

• Bitcoin features that were experimental. This includes: using IRC to find peer addresses (in irc.cpp and irc.h), marketplace/product/review (market.cpp and market.h), and sending bitcoins to an IP address. Code related to GUI.

Other tips

• Just get started. Don't try to read a lot of theories about bitcoin before you start. The code is pretty clear. Only look up an unfamiliar concept when needed (like merkel tree).
• Don't be afraid to skip code. For example, the algorithm to select the UTXO is very long but can be safely skipped https://github.com/bitcoin/bitcoin/blob/v0.1.5/main.cpp#L2440). Focus on the concept and workflow.
• Don't try to compile the project because it's a very old release and requires old dependencies too.

Links and resources

• Read the original bitcoin paper and the book Mastering Bitcoin for general knowledge.
• Understanding Bitcoin Source Code. Still a work in progress.