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Bitcoin Protocol components in Common Lisp
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tests tests: add validation test for common transaction types Oct 20, 2019
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README.md

BP - Bitcoin Protocol

Quicklisp Build Status

This is a Common Lisp implementation of the various components of the Bitcoin Protocol. The serialization/deserialization utils may be used for reading the block data both from peers and from local database on disk. The cryptographic utilities are aggregated from FFI bindings to the secp256k1 and ironclad. HTTP client code uses aserve, while and JSON handling is done with jsown package.

THIS BITCOIN CONSENSUS RULES IMPLEMENTATION IS NOT, AND WILL PROBABLY NEVER BE FULLY COMPLIANT WITH BITCOIN CORE IMPLEMENTATION. DO NOT RELY ON IT FOR VALIDATING YOUR MAINNET TRANSACTIONS, AS IT MAY EASILY PUT YOU OUT OF SYNC WITH THE NETWORK IN A LOT OF CORNER CASES.

Installation

Elliptic curve cryptography utilities (transaction signing and verification) use a secp256k1 library, so it must be installed before building the bp system (either manually, or using the system package manager if available):

# Ubuntu
apt install libsecp256k1 libsecp256k1-dev

# Arch Linux
pacman -Syu libsecp256k1

# macOS
brew tap cuber/homebrew-libsecp256k1
brew install libsecp256k1

Once secp256k1 is ready, bp can be installed via quicklisp tool:

(ql:quickload "bp")

Alternatively, bp system can be loaded from sources, assuming the following Common Lisp packages are available locally:

In order to load bp from sources, evaluate the following form (this assumes that ASDF is able to find the system definition; more on that here):

(asdf:load-system "bp")

Interface

Currently, this library only provides utilities for stateless interaction with Bitcoin from REPL. Storage, wallet and full node capabilities are somewhere in a distant future.

Chain interface

Functions bp:get-block-hash, bp:get-block and bp:get-transaction allow to pull chain data from any external supplier specified with the bp:with-chain-supplier macro:

CL-USER> (bp:with-chain-supplier (bp:node-connection
                                  :url "http://localhost:8332"
                                  :username "btcuser"
                                  :password "btcpassword")
           (bp:get-transaction "0e3e2357e806b6cdb1f70b54c3a3a17b6714ee1f0e68bebb44a74b1efd512098"))
#<BP/CORE/TRANSACTION:TX 0e3e2357e806b6cdb1f70b54c3a3a17b6714ee1f0e68bebb44a74b1efd512098>

Non-nil keyword argument :encoded can be used with bp:get-block and bp:get-transaction to return serialized transaction hex-encoded in a string:

CL-USER> (bp:get-transaction "14...c3" :encoded t)
"010000000...ae00000000"

Under the hood, these operations call corresponding generic functions bp:chain-get-{block-hash,block,transaction} which take the supplier object as an explicit first argument.

Model and serialization

Bitcoin data entities are represented by the following structures:

  • bp:block-header;
  • bp:cblock;
  • bp:tx;
  • bp:txin;
  • bp:txout;
  • bp:script.

Functions named bp:block-* (both for bp:block-header and bp:cblock), bp:tx-*, bp:txin-* and bp:txout-* provide access to the components of the corresponding entities.

Functions bp:parse and bp:serialize can be used to read and write any Bitcoin entity from and to any octet stream respectively:

CL-USER> (ironclad:with-octet-input-stream (stream #(1 0 ... 0 0))
           (bp:parse 'bp:tx in-stream))
#<BP/CORE/TRANSACTION:TX 17e590f116d3deeb9b121bbb1c37b7916e6b7859461a3af7edf74e2348a9b347>
CL-USER> (ironclad:with-octet-output-stream (stream)
           (bp:parse 'tx out-stream))
#(1 0 ... 0 0)

Note that while bp:serialize function take an entity as its first argument, bp:parse takes the symbol naming the class of the entity, behaving as class method.

Functions bp:decode and bp:encode wrap above functions to decode and encode Bitcoin entities from and to hex-encoded strings:

CL-USER> (bp:decode 'bp:tx "0100000002f8615378...e097a988ac00000000")
#<BP/CORE/TRANSACTION:TX 17e590f116d3deeb9b121bbb1c37b7916e6b7859461a3af7edf74e2348a9b347>
CL-USER> (bp:encode *)
"0100000002f8615378...e097a988ac00000000"

Validation

Functions bp:validate and bp:validp take an entity as well as the optional context parameters, and validate it according to an approximation of Bitcoin consensus rules.

Both functions return t if the entity is valid, but the bp:validate function signals an error otherwise, while the bp:validp function simply returns nil.

Both functions assume the chain supplier context (i.e. they are called within the body of bp:with-chain-supplier).

Dynamic variable bp:*trace-script-execution* can be used to enable printing the steps of script execution (chain supplier macro omitted):

CL-USER> (setf bp:*trace-script-execution* t)
t
CL-USER> (bp:validate
          (bp:get-transaction "17e590f116d3deeb9b121bbb1c37b7916e6b7859461a3af7edf74e2348a9b347"))
op:       OP_PUSH22
payload:  #(0 14 a4 b4 ca 48 de b 3f ff c1 54 4 a1 ac dc 8d ba ae 22 69
            55)
commands: <>
stack:    ()

op:       OP_HASH160
payload:  -
commands: <OP_PUSH20 OP_EQUAL>
stack:    (#(0 14 a4 b4 ca 48 de b 3f ff c1 54 4 a1 ac dc 8d ba ae 22
             69 55))

op:       OP_PUSH20
payload:  #(29 28 f4 3a f1 8d 2d 60 e8 a8 43 54 d 80 86 b3 5 34 13 39)
commands: <OP_EQUAL>
stack:    (#(29 28 f4 3a f1 8d 2d 60 e8 a8 43 54 d 80 86 b3 5 34 13 39))

op:       OP_EQUAL
payload:  -
commands: <>
stack:    (#(29 28 f4 3a f1 8d 2d 60 e8 a8 43 54 d 80 86 b3 5 34 13 39)
           #(29 28 f4 3a f1 8d 2d 60 e8 a8 43 54 d 80 86 b3 5 34 13 39))

op:       OP_FALSE
payload:  -
commands: <OP_PUSH20>
stack:    ()

op:       OP_PUSH20
payload:  #(a4 b4 ca 48 de b 3f ff c1 54 4 a1 ac dc 8d ba ae 22 69 55)
commands: <>
stack:    (#())

t
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