Libbitcoin presentation for SF Bitcoin Devs. Given on 2015-03-02.

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