CoreBitcoin is an implementation of Bitcoin protocol in Objective-C. When it is completed, it will let you create an application that acts as a full Bitcoin node. You can encode/decode addresses, apply various hash functions, sign and verify messages and parse some data structures. Transaction support is still incomplete.

The only external dependency is OpenSSL (used for Bignum, ECC and RIPEMD160). Today OpenSSL source is stored in this repo and is built with update_openssl.sh script. OpenSSL binaries are OSX-only and committed in the repo. This is far from perfect and binary does not support iOS architectures. This will be fixed in the future.

Ideally, we wouldn't require OpenSSL at all, but keep in mind that BitcoinQT uses OpenSSL and some of its quirks are now a part of the protocol. So if you are going to reimplement ECC, it must be bug-to-bug compatible with OpenSSL implementation.

Clone this repo and make sure you can run "UnitTests" target. It is a simple command-line app that runs a bunch of asserts. If nothing fails, the program silently exits.

If it works well, add this repo as a submodule to your project. Then add all source files, OpenSSL headers, libcrypto.a and libssl.a.

In your project settings, add $(SRCROOT)/CoreBitcoin/openssl/include to "Headers Search Paths" and $(SRCROOT)/CoreBitcoin/openssl/lib in "Library Search Paths".

If this sounds cumbersome, there is a bounty for creating a CoreBitcoin.framework to simplify integration process.

• Universal OpenSSL libraries. Or as a part of a build process.
• Universal CoreBitcoin.framework bundle with OpenSSL inside.
• Full transaction support.
• Full blockchain support.
• Unit tests for EC sign/verify.
• Unit tests for transaction parsing/serialization.
• Modern unit test suite.
• Security analysis. Do we use truly random numbers? Do we sign things correctly? Do we have buffer overflows? And so on.

• 1 BTC for building CoreBitcoin.framework with support for x86_64, armv7, armv7s. OpenSSL should be bundled inside. [@oleganza]

To add your own bounty, add a line here (or edit an existing one), make a pull request and donate to the address below. Your donation will be reserved for that bounty only. I will contact you to check if the implementation is acceptable before paying out.

Feel free to open issues, drop me pull requests or contact me to discuss how to do things.

Code style: follow existing style and use 4 spaces instead of tabs. There's no line width limit.

Email: oleganza@gmail.com

Twitter: @oleganza

Please send your donations here: 1CBtcGivXmHQ8ZqdPgeMfcpQNJrqTrSAcG.

All funds will be used only for bounties to fix stuff. Every withdrawal from this address will be documented.

You can also donate for a specific bounty. The amount will be reserved for that bounty and listed above.

Released under the WTFPL except for OpenSSL. It is not MIT License because no one reads your legalese anyway and it only adds burden. Instead, you are encouraged to donate money for development.