Libbitcoin is an open source C++ Bitcoin blockchain toolkit that includes several libraries for building blockchain applications and services. It includes libraries for the blockchain database (libbitcoin-blockchain), a server API (libbitcoin-server), a client wrapper for the API (libbitcoin-client), and a command line interface (libbitcoin-explorer). Libbitcoin aims to provide a complete third-party implementation of the Bitcoin protocol that is not controlled by any single entity.

1. libbitcoin

2. Typical Bitcoin Company
Application
Centralized
API
Provider
Gem, Chain,
Blockchain.info,
Coinbase,
BlockCypher, ...
Shopping, Escrow,
Smart contracts,
Tipping, etc...

3. libbitcoin is a Blockchain API
Application
libbitcoin-
server
Open Source,
Decentralized
Shopping, Escrow,
Smart contracts,
Tipping, etc...

4. libbitcoin is a Power-user CLI Tool
libbitcoin-
explorer
(BX)
libbitcoin-
server
Scripting, Research,
Exploration, ...
$ bx fetch-height
345896

5. libbitcoin is a Blockchain Toolkit
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

6. Why does this matter?
● Right now, most of the network runs a single
piece of software (the Satoshi node)
● The Bitcoin Foundation controls this software
● Monocultures are bad!
● libbitcoin is a complete third-party Bitcoin
Blockchain implementation

7. libbitcoin Users
● DarkWallet
● OpenBazaar
● AirBitz

8. libbitcoin Tour
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

9. libbitcoin
● Modern C++11 codebase.
● Designed as a collection of simple, decoupled
classes
● You can use as much or as little funtionality
as you like

10. libbitcoin
● Basic blockchain types
– Blocks, Transactions, Scripts, Crypto primitives, ...
● Wallet types
– Base58, Addresses, URLs, HD keys, Message signing, …
● P2P Protocol

11. libbitcoin Tour
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

12. libbitcoin-blockchain
● High-performance blockchain database
● Custom-designed on-disk hash table
● Rich indexes for high-speed queries
– Transactions
– Addresses
– Stealth

13. libbitcoin Tour
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

14. libbitcoin-server
● Formerly known as “obelisk”
● Provides a low-level Blockchain API
● Uses ZeroMQ

15. libbitcoin-server
● fetch_history
● fetch_transaction
● fetch_last_height
● fetch_block_header
● fetch_transaction_index
● fetch_stealth
● broadcast_transaction
● subscribe

16. libbitcoin Tour
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

17. libbitcoin-client
● C++ wrapper around the libbitcoin-server RPC
interface
● Server API calls are as easy as calling a C++
function

18. darkwallet/python-obelisk
● For those who want to use libbitcoin-server
from python

19. darkwallet/gateway
● Bridges libbitcoin-server to Websockets
● For those who want to use libbitcoin-server
from Javascript

20. libbitcoin Tour
libbitcoin
libbitcoin-blockchain libbitcoin-client
libbitcoin-node
libbitcoin-server
libbitcoin-explorer
Server Stack Client Stack

21. libbitcoin-explorer
● Short name is “bx”
● Replaces an earlier project called “sx”
● Command-line interface to lots of Bitcoin
goodies

22. libbitcoin-explorer
● Server Commands
– fetch-balance, fetch-header, fetch-height,
fetch-history, fetch-public-key, fetch-
stealth, fetch-tx, fetch-tx-index, fetch-utxo
● Wallet
– input-set, input-sign, input-validate,
message-sign, message-validate, send-tx,
send-tx-node, send-tx-p2p, tx-decode, tx-
encode, tx-sign

23. libbitcoin-explorer
● HD Keys
– hd-new, hd-private, hd-public, hd-to-address, hd-
to-ec, hd-to-public, hd-to-wif
●
EC Math
– ec-add, ec-add-secrets, ec-lock, ec-multiply, ec-
multiply-secrets, ec-new, ec-to-address, ec-to-
public, ec-to-wif, ec-unlock
● Hashes
– bitcoin160, bitcoin256, sha160, sha256, sha512,
ripemd160

24. libbitcoin-explorer
● Format conversions
– address-decode, address-encode
– base16-decode, base16-encode
– base58-decode, base58-encode
– base64-decode, base64-encode
– btc-to-satoshi, satoshi-to-btc
– wif-to-ec, wif-to-public
● And lots more…

25. Installing bx
● Available as a single-file pre-compiled binary:
– https://github.com/libbitcoin/libbitcoin-
explorer/wiki/Download-BX
– Linux, OS X, and Windows!
● Or you can compile it yourself:
– https://github.com/libbitcoin/libbitcoin-explorer
– Use the install.sh script for an hands-off compile, including
dependencies
– Or follow the manual build instructions

26. Installing libbitcoin-server
● Stable binaries are not yet available
– Hopefully soon!
● Source code is here:
– https://github.com/libbitcoin/libbitcoin-server
● To run:
$ initchain
$ bitcoin_server

27. libbitcoin-server Servers
● https://wiki.unsystem.net/en/index.php/Obelisk/Servers
● The BX default is tcp://obelisk.airbitz.co:9091
● Feel free to use the AirBitz servers!
– If you install your own servers,
please let us use them too

28. Installing libbitcoin
● Source code is here:
– https://github.com/libbitcoin/libbitcoin

29. libbitcoin Example
#include <bitcoin/bitcoin.hpp>
#include <iostream>
#include <string.h>
int main()
{
char line[256];
std::cout << "Please enter a secret phrase: ";
std::cin.getline(line, 256);
bc::data_chunk seed(line, line + strlen(line));
bc::hash_digest hash = bc::sha256_hash(seed);
std::cout << "Hash: " << bc::encode_base16(hash) << std::endl;
std::cout << "Private key: " << bc::secret_to_wif(hash) << std::endl;
bc::payment_address address;
bc::set_public_key_hash(address,
bc::bitcoin_short_hash(bc::secret_to_public_key(hash)));
std::cout << "Address: " << address.encoded() << std::endl;
return 0;
}

30. libbitcoin Example - Header
#include <bitcoin/bitcoin.hpp>

31. libbitcoin Example – Grab some text
char line[256];
std::cout << "Please enter a secret phrase: ";
std::cin.getline(line, 256);
bc::data_chunk seed(line, line + strlen(line));

32. libbitcoin Example – Hashing
bc::hash_digest hash = bc::sha256_hash(seed);
std::cout << "Hash: " <<
bc::encode_base16(hash) << std::endl;
std::cout << "Private key: " <<
bc::secret_to_wif(hash) << std::endl;

33. libbitcoin Example – Addresses
bc::payment_address address;
bc::set_public_key_hash(address,
bc::bitcoin_short_hash(
bc::secret_to_public_key(hash)));
std::cout << "Address: " <<
address.encoded() << std::endl;

34. libbitcoin Example – Makefile
CXXFLAGS = $(shell pkg-config --cflags libbitcoin)
LIBS = $(shell pkg-config --libs libbitcoin)
test: test.o
$(CXX) -o test test.o $(LIBS)
test.o: test.cpp
$(CXX) -c -o test.o test.cpp $(CXXFLAGS)

35. Future Plans
● New libbitcoin-server protocol
– We want a full query language
– libbitcoin-protocol
● SPV client library
– libitcoin-server is fast, so we don't want to lose that
– The client uses block headers to verify server responses

36. Slides
● Slides are here:
– http://www.slideshare.net/swansontec/libbitcoin-
slides