Get Paid in Bitcoin

A presentation about using Elixir to generate a Bitcoin Address from a private key, with the help of external Python and C++ Bitcoin libraries.

Presented at the Elixir Sydney meetup on 7 Feb 2018.

Presentation slide deck markdown and speaker notes (useable in Deckset):
https://github.com/paulfioravanti/presentations/tree/master/get_paid_in_bitcoin

Transcript

1. Get P id in @paulfioravanti 1/149
8. @paulfioravanti 8/149
9. ExCrypto https://github.com/ntrepid8/ex_crypto @paulfioravanti 9/149
10. ExCrypto https://github.com/ntrepid8/ex_crypto RSA Ex https://github.com/anoskov/rsa-ex @paulfioravanti 10/149
11. @paulfioravanti 11/149
12. ut
13. Generate Bitcoin Address @paulfioravanti 13/149
14. We need: A private key @paulfioravanti 14/149
15. We need: Bitcoin public key (from private key) @paulfioravanti 15/149
16. We need: Bitcoin address (from Bitcoin public key) @paulfioravanti 16/149
17. Checklist - Private Key - Bitcoin Public Key - Bitcoin Address @paulfioravanti 17/149
19. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 19/149
20. Bitcoin Public Key @paulfioravanti 20/149
21. Elliptic Curve Digital Signature Algorithm @paulfioravanti 21/149
22. Elliptic Curve Digital Signature Algorithm @paulfioravanti 22/149
23. ECDSA secp256k1 @paulfioravanti
24. ECDSA secp256k1 {x,y} coordinate on the Elliptic Curve @paulfioravanti
25. Anyway... @paulfioravanti 25/149
26. @paulfioravanti 26/149
27. bitcoin-elixir — h!ps://github.com/comboy/bitcoin-elixir @paulfioravanti 27/149
28. bitcoin-elixir — h!ps://github.com/comboy/bitcoin-elixir Bitcoin-Ex — h!ps://github.com/justinlynn/bitcoin-ex @paulfioravanti 28/149
29. ut
30. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 30/149
31. NOW WHAT? @paulfioravanti 31/149
32. NOPE! @paulfioravanti 32/149
33. ut
34. @paulfioravanti 34/149
35. 35/149
36. @paulfioravanti 36/149
37. @paulfioravanti 37/149
38. @paulfioravanti 38/149
39. New project! $ mix new bitcoin_address $ cd bitcoin_address $ mix deps.get @paulfioravanti 39/149
40. Pybitcointools — h!ps://github.com/vbuterin/pybitcointools $ pip install bitcoin @paulfioravanti 40/149
41. Python Code priv/bitcoin_address.py @paulfioravanti 41/149
42. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 42/149
43. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 43/149
44. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 44/149
45. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 45/149
46. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 46/149
47. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 47/149
48. bitcoin_address.py import bitcoin def create_bitcoin_public_key(private_key): decoded_private_key = bitcoin.decode_privkey(private_key, "hex") public_key = bitcoin.fast_multiply(bitcoin.G, decoded_private_key) (public_key_x, public_key_y) = public_key compressed_prefix = "02" if (public_key_y % 2) == 0 else "03" return compressed_prefix + bitcoin.encode(public_key_x, 16, 64) @paulfioravanti 48/149
49. Export — h!ps://github.com/fazibear/ export @paulfioravanti 49/149
50. Erlport — h!ps://github.com/hdima/ erlport @paulfioravanti 50/149
51. @paulfioravanti 51/149
52. Install defp deps do [ # Erlport wrapper for Elixir to interface with Python code {:export, "~> 0.1.0"} ] end @paulfioravanti 52/149
53. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") Python.stop(pid) end end defp create_bitcoin_public_key(pid, private_key) do pid |> Python.call(@python_file, "create_bitcoin_public_key", [private_key]) |> to_string() end end @paulfioravanti 53/149
54. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" # ... end @paulfioravanti 54/149
55. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" # ... end @paulfioravanti 55/149
56. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" # ... end @paulfioravanti 56/149
57. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... Python.stop(pid) end end # ... end @paulfioravanti 57/149
58. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... Python.stop(pid) end end # ... end @paulfioravanti 58/149
59. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... Python.stop(pid) end end # ... end @paulfioravanti 59/149
60. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... Python.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do pid |> Python.call(@python_file, "create_bitcoin_public_key", [priv_key]) |> to_string() end end @paulfioravanti 60/149
61. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") Python.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do # ... end end @paulfioravanti 61/149
62. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") Python.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do pid |> Python.call(@python_file, "create_bitcoin_public_key", [priv_key]) |> to_string() end end @paulfioravanti 62/149
63. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 63/149
64. bitcoin.pubkey_to_address @paulfioravanti 64/149
65. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, bitcoin_public_key) do # ... end end defp create_bitcoin_address(pid, pub_key) do pid |> Python.call(@python_file, "bitcoin.pubkey_to_address", [pub_key]) |> to_string() end end @paulfioravanti 65/149
66. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, bitcoin_public_key) do # ... end end defp create_bitcoin_address(pid, pub_key) do pid |> Python.call(@python_file, "bitcoin.pubkey_to_address", [pub_key]) |> to_string() end end @paulfioravanti 66/149
67. defp create_bitcoin_public_key(pid, priv_key) do pid |> Python.call(@python_file, "create_bitcoin_public_key", [priv_key]) |> to_string() end defp create_bitcoin_address(pid, pub_key) do pid |> Python.call(@python_file, "bitcoin.pubkey_to_address", [pub_key]) |> to_string() end @paulfioravanti 67/149
68. defp create_bitcoin_public_key(pid, priv_key) do pid |> Python.call(@python_file, "create_bitcoin_public_key", [priv_key]) |> to_string() end defp create_bitcoin_address(pid, pub_key) do pid |> Python.call(@python_file, "bitcoin.pubkey_to_address", [pub_key]) |> to_string() end @paulfioravanti 68/149
69. defmodule BitcoinAddress.Python do # ... def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, bitcoin_public_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") IO.puts("Bitcoin address: #{inspect(bitcoin_address)}") Python.stop(pid) end end defp create_bitcoin_address(pid, pub_key) do pid |> Python.call(@python_file, "bitcoin.pubkey_to_address", [pub_key]) |> to_string() end end @paulfioravanti 69/149
70. defmodule BitcoinAddress.Python do use Export.Python @python_path :bitcoin_address |> :code.priv_dir() |> Path.basename() @python_file "bitcoin_address" def generate(private_key) do with {:ok, pid} <- Python.start(python_path: @python_path), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, bitcoin_public_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") IO.puts("Bitcoin address: #{inspect(bitcoin_address)}") Python.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do call_python(pid, "create_bitcoin_public_key", [priv_key]) end defp create_bitcoin_address(pid, pub_key) do call_python(pid, "bitcoin.pubkey_to_address", [pub_key]) end defp call_python(pid, function, args) do pid |> Python.call(@python_file, function, args) |> to_string() end end @paulfioravanti 70/149
71. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 71/149
74. 74/149
76. @paulfioravanti 76/149
77. Cure — h!ps://github.com/luc-tielen/ Cure @paulfioravanti 77/149
78. $ brew install libbitcoin @paulfioravanti 78/149
79. Install defp deps do [ # Interface C-code with Erlang/Elixir using Ports {:cure, "~> 0.4.0"}, ] end @paulfioravanti 79/149
80. $ mix cure.bootstrap @paulfioravanti 80/149
81. Cure Bootstrap c_src ᵓᴷ Makefile ᵓᴷ main.c ᵋᴷ main.h @paulfioravanti 81/149
82. Cure Bootstrap c_src ᵓᴷ Makefile ᵓᴷ main.c ᵋᴷ main.h @paulfioravanti 82/149
83. Cure Bootstrap c_src ᵓᴷ Makefile ᵓᴷ main.c ᵋᴷ main.h @paulfioravanti 83/149
84. Cure Bootstrap c_src ᵓᴷ Makefile ᵓᴷ main.c ᵋᴷ main.h @paulfioravanti 84/149
85. main.c #include "main.h" int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { // TODO put C-code here, right now it only echos data back // to Elixir. send_msg(buffer, bytes_read); } return 0; } @paulfioravanti 85/149
86. main.c #include "main.h" int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { // TODO put C-code here, right now it only echos data back // to Elixir. send_msg(buffer, bytes_read); } return 0; } @paulfioravanti 86/149
87. main.c #include "main.h" int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { // TODO put C-code here, right now it only echos data back // to Elixir. send_msg(buffer, bytes_read); } return 0; } @paulfioravanti 87/149
88. main.c #include "main.h" int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { // TODO put C-code here, right now it only echos data back // to Elixir. send_msg(buffer, bytes_read); } return 0; } @paulfioravanti 88/149
89. Rename Files $ mv c_src/main.h c_src/bitcoin_address.h $ mv c_src/main.c c_src/bitcoin_address.cpp @paulfioravanti 89/149
90. bitcoin_address.h #ifndef BITCOIN_ADDRESS_H #define BITCOIN_ADDRESS_H #include <elixir_comm.h> std::string create_bitcoin_public_key(std::string priv_key); #endif @paulfioravanti 90/149
91. bitcoin_address.cpp #include <string> #include "bitcoin_address.h" int main(void) { ... } std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 91/149
92. bitcoin_address.cpp std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 92/149
93. bitcoin_address.cpp std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 93/149
94. bitcoin_address.cpp std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 94/149
95. bitcoin_address.cpp std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 95/149
96. bitcoin_address.cpp std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 96/149
97. bitcoin_address.cpp #include <string> #include "bitcoin_address.h" int main(void) { ... } std::string create_bitcoin_public_key(std::string priv_key) { bc::ec_secret decoded; bc::decode_base16(decoded, priv_key); bc::wallet::ec_private secret(decoded, bc::wallet::ec_private::mainnet_p2kh); bc::wallet::ec_public public_key(secret); return public_key.encoded(); } @paulfioravanti 97/149
98. bitcoin_address.cpp int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { // TODO put C-code here, right now it only echos data back // to Elixir. send_msg(buffer, bytes_read); } return 0; } @paulfioravanti 98/149
99. Just send function name & private key? @paulfioravanti 99/149
100. Just send function name & private key? @paulfioravanti 100/149
101. Send Flag ! @paulfioravanti 101/149
102. Send Flag ! const int CREATE_BITCOIN_PUBLIC_KEY = 1; @paulfioravanti 102/149
103. bitcoin_address.cpp const int CREATE_BITCOIN_PUBLIC_KEY = 1; int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { process_command(buffer, bytes_read); } return 0; } @paulfioravanti 103/149
104. bitcoin_address.cpp const int CREATE_BITCOIN_PUBLIC_KEY = 1; int main(void) { int bytes_read; byte buffer[MAX_BUFFER_SIZE]; while((bytes_read = read_msg(buffer)) > 0) { process_command(buffer, bytes_read); } return 0; } @paulfioravanti 104/149
105. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 105/149
106. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 106/149
107. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 107/149
108. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 108/149
109. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 109/149
110. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 110/149
111. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 111/149
112. bitcoin_address.cpp void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 112/149
113. @paulfioravanti 113/149
114. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Bitcoin public key: #{inspect(bitcoin_public_key)}") :ok = Cure.stop(pid) end end defp create_bitcoin_public_key(pid, private_key) do Cure.send_data(pid, <<@create_bitcoin_public_key, private_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 114/149
115. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 # ... end @paulfioravanti 115/149
116. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 # ... end @paulfioravanti 116/149
117. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 # ... end @paulfioravanti 117/149
118. defmodule BitcoinAddress.CPlusPlus do # ... def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... :ok = Cure.stop(pid) end end # ... end @paulfioravanti 118/149
119. defmodule BitcoinAddress.CPlusPlus do # ... def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... :ok = Cure.stop(pid) end end # ... end @paulfioravanti 119/149
120. defmodule BitcoinAddress.CPlusPlus do # ... def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... :ok = Cure.stop(pid) end end # ... end @paulfioravanti 120/149
121. defmodule BitcoinAddress.CPlusPlus do # ... def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do # ... :ok = Cure.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do Cure.send_data(pid, <<@create_bitcoin_public_key, priv_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 121/149
122. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Bitcoin public key: #{inspect(bitcoin_public_key)}") :ok = Cure.stop(pid) end end defp create_bitcoin_public_key(pid, private_key) do Cure.send_data(pid, <<@create_bitcoin_public_key, priv_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 122/149
123. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 123/149
124. bitcoin_address.cpp std::string create_bitcoin_address(std::string pub_key) { bc::wallet::ec_public public_key = bc::wallet::ec_public::ec_public(pub_key); bc::data_chunk public_key_data; public_key.to_data(public_key_data); const auto hash = bc::bitcoin_short_hash(public_key_data); bc::data_chunk unencoded_address; unencoded_address.reserve(25); unencoded_address.push_back(0); bc::extend_data(unencoded_address, hash); bc::append_checksum(unencoded_address); const std::string address = bc::encode_base58(unencoded_address); return address; } @paulfioravanti 124/149
125. const int CREATE_BITCOIN_PUBLIC_KEY = 1; const int CREATE_BITCOIN_ADDRESS = 2; int main(void) { ... } void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; case CREATE_BITCOIN_ADDRESS: result = create_bitcoin_address(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 125/149
126. const int CREATE_BITCOIN_PUBLIC_KEY = 1; const int CREATE_BITCOIN_ADDRESS = 2; int main(void) { ... } void process_command(byte* buffer, int bytes_read) { int function = buffer[0]; std::string arg = (char*) &buffer[1]; std::string result; switch (function) { case CREATE_BITCOIN_PUBLIC_KEY: result = create_bitcoin_public_key(arg); break; case CREATE_BITCOIN_ADDRESS: result = create_bitcoin_address(arg); break; } memcpy(buffer, result.data(), result.length()); send_msg(buffer, result.size()); } @paulfioravanti 126/149
127. defmodule BitcoinAddress.CPlusPlus do @create_bitcoin_public_key 1 @create_bitcoin_address 2 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, public_key) do # ... end end defp create_bitcoin_address(pid, pub_key) do Cure.send_data(pid, <<@create_bitcoin_address, pub_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 127/149
128. defmodule BitcoinAddress.CPlusPlus do @create_bitcoin_public_key 1 @create_bitcoin_address 2 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, public_key) do # ... end end defp create_bitcoin_address(pid, pub_key) do Cure.send_data(pid, <<@create_bitcoin_address, pub_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 128/149
129. defmodule BitcoinAddress.CPlusPlus do @create_bitcoin_public_key 1 @create_bitcoin_address 2 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, public_key) do # ... end end defp create_bitcoin_address(pid, pub_key) do Cure.send_data(pid, <<@create_bitcoin_address, pub_key::binary>>, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 129/149
130. defmodule BitcoinAddress.CPlusPlus do alias Cure.Server, as: Cure @cpp_executable "priv/bitcoin_address" # Integers representing C++ methods @create_bitcoin_public_key 1 @create_bitcoin_address 2 def generate(private_key) do with {:ok, pid} <- Cure.start_link(@cpp_executable), bitcoin_public_key <- create_bitcoin_public_key(pid, private_key), bitcoin_address <- create_bitcoin_address(pid, bitcoin_public_key) do IO.puts("Private key: #{inspect(private_key)}") IO.puts("Public key: #{inspect(bitcoin_public_key)}") IO.puts("Bitcoin address: #{inspect(bitcoin_address)}") :ok = Cure.stop(pid) end end defp create_bitcoin_public_key(pid, priv_key) do call_cpp(pid, <<@create_bitcoin_public_key, priv_key::binary>>) end defp create_bitcoin_address(pid, pub_key) do call_cpp(pid, <<@create_bitcoin_address, pub_key::binary>>) end defp call_cpp(pid, data) do Cure.send_data(pid, data, :once) receive do {:cure_data, response} -> response end end end @paulfioravanti 130/149
131. Checklist - Private Key ✅ - Bitcoin Public Key - Bitcoin Address @paulfioravanti 131/149
132. ut
133. Makefile @paulfioravanti 133/149
134. Makefile ! CC = g++ -std=c++11 APP_DIR = $(shell dirname $(shell pwd)) CURE_DEPS_DIR = $(APP_DIR)/deps/cure/c_src CURE_DEPS = -I$(CURE_DEPS_DIR) -L$(CURE_DEPS_DIR) ELIXIR_COMM_C = -x c++ $(CURE_DEPS_DIR)/elixir_comm.c LIBBITCOIN_DEPS = $(shell pkg-config --cflags --libs libbitcoin) C_FLAGS = $(CURE_DEPS) $(ELIXIR_COMM_C) $(LIBBITCOIN_DEPS) -O3 PRIV_DIR = $(APP_DIR)/priv C_SRC_DIR = $(APP_DIR)/c_src EXECUTABLES = bitcoin_address all: $(EXECUTABLES) # * $< - prerequisite file # * $@ - executable file $(EXECUTABLES): %: %.cpp $(CC) $(C_FLAGS) $(C_SRC_DIR)/$< -o $(PRIV_DIR)/$@ @paulfioravanti 134/149
135. Compile from c_src/ to priv/ all: $(EXECUTABLES) # * $< - prerequisite file # * $@ - executable file $(EXECUTABLES): %: %.cpp $(CC) $(C_FLAGS) $(C_SRC_DIR)/$< -o $(PRIV_DIR)/$@ @paulfioravanti 135/149
136. Compile C++ with Elixir defmodule BitcoinAddress.Mixfile do use Mix.Project def project do [ # ... compilers: Mix.compilers ++ [:cure, :"cure.deps"] ] end # ... end @paulfioravanti 136/149
137. Compile during TDD if Mix.env() == :dev do config :mix_test_watch, clear: true, tasks: [ "compile.cure", "format", "test", "credo --strict" ] end @paulfioravanti 137/149
138. Anyway... @paulfioravanti 138/149
142. @paulfioravanti 142/149
143. Self-Promotion — h!ps://paulfioravanti.com/blog/2017/12/04/using- pythons-bitcoin-libraries-in-elixir/ — h!ps://paulfioravanti.com/blog/2017/12/13/using-c- plus-plus-bitcoin-libraries-in-elixir/ @paulfioravanti 143/149
144. Github Repos — h!ps://github.com/paulfioravanti/bitcoin_address — h!ps://github.com/paulfioravanti/mastering_bitcoin @paulfioravanti 144/149
145. Ironically enough... @paulfioravanti 145/149
147. @paulfioravanti 147/149
149. Thanks! @paulfioravanti