Bitcoin-S-Sidechains

This is a base implementation for a sidechain in Scala. There are currently two branches under development on this repository

• Mainchain - this is a slightly modified version of bitcoin to support the validation of SPV proofs. This is a soft fork change as described in section 3.2 in the sidechains whitepaper
• Alpha - this is the actual sidechain implementation where all new op codes, experimental features etc. happen

What are sidechains?

Sidechains are a blockchain that is pegged to another blockchain. An example of this could be a sidechain designed to facilitate sports betting that is pegged to the bitcoin blockchain. For more information on the design of sidechains please see the whitepaper.

Goal

This implementation of a sidechain is designed to be a base implementation for which other sidechains (and their features) can be built off of. For the most part, it is going to mirror the elements project. This project aims to provide a solid base implementation on the JVM.

TODO:

• Implement verification of SPV proofs inside of the mainchain branch
• Implement REORGPROOFVERIFY & WITHDRAWPROOFVERIFY
• Implement disabled op codes in Bitcoin (OP_OR, OP_AND, OP_XOR...)
• Signed blocks
• Deterministic Pegs

Examples from Bitcoin-S-Core

Bitcoin-S-Sidechains is a fork of Bitcoin-S-Core. Here are examples of how Bitcoin-S-Core works and how to run the test cases.

Quick Build Guide

This repostitory includes the following functionality:

• Native Scala objects for various protocol types (Transaction, TransactionInput, ScriptSignatures...)
• Serializers and deserializers for bitcoin data structures mentioned above
• An implementation of Bitcoin's Script programming language
  • Passes all tests found in Bitcoin Core's regression test suite called script_test.json
  • Passes all tests inside of Bitcoin Core's transaction regression test suite tx_valid.json / tx_invalid.json / sighash.json
  • Currently up to date through segregated witness
• 90% test coverage throughout the codebase to ensure high quality code.
• Functions documented with Scaladocs for user friendliness

Design Principles

• Immutable data structures everywhere
• Algebraic Data Types to allow the compiler to check for exhaustiveness on match statements
• Favoring readability over terseness

Examples from Bitcoin-S-Core

Bitcoin-S-Sidechains is a fork of Bitcoin-S-Core. Here are examples of how Bitcoin-S-Core works and how to run the test cases.

Examples

Here is an example scala console session with bitcoins-core

chris@chris:~/dev/bitcoins-core-chris$ sbt console

scala> import org.bitcoins.core.protocol.transaction._
import org.bitcoins.protocol.transaction._

scala> import org.bitcoins.core.protocol.script._
import org.bitcoins.protocol.script._

scala> val simpleRawTransaction = "0100000001ccf318f0cbac588a680bbad075aebdda1f211c94ba28125b0f627f9248310db3000000006b4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353ffffffff0210335d05000000001976a914b1d7591b69e9def0feb13254bace942923c7922d88ac48030000000000001976a9145e690c865c2f6f7a9710a474154ab1423abb5b9288ac00000000"
simpleRawTransaction: String = 0100000001ccf318f0cbac588a680bbad075aebdda1f211c94ba28125b0f627f9248310db3000000006b4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353ffffffff0210335d05000000001976a914b1d7591b69e9def0feb13254bace942923c7922d88ac48030000000000001976a9145e690c865c2f6f7a9710a474154ab1423abb5b9288ac00000000

scala> val tx = Transaction(simpleRawTransaction)
tx: org.bitcoins.core.protocol.transaction.Transaction = TransactionImpl(1,List(TransactionInputImpl(TransactionOutPointImpl(b30d3148927f620f5b1228ba941c211fdabdae75d0ba0b688a58accbf018f3cc,0),P2PKHScriptSignatureImpl(4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353,List(BytesToPushOntoStackImpl(72), ScriptConstantImpl(30450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01), BytesToPushOntoStackImpl(33), ScriptConstantImpl(0241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353))),4294967295)),List(TransactionOutputImpl(89994000 ...

This gives us an example of a bitcoin transaction that is encoded in hex format that is deserialized to a native Scala object called a Transaction.

Transactions are run through the interpreter to check the validity of the Transaction. These are packaged up into an object called ScriptProgram, which contains the following:

• The transaction that is being checked
• The specific input index that it is checking
• The scriptPubKey for the crediting transaction
• The flags used to verify the script

Here is an example of a transaction spending a scriptPubKey which is correctly evaluated with our interpreter implementation:

chris@chris:~/dev/bitcoins-core$ sbt console
[info] Loading project definition from /home/chris/dev/bitcoins-core/project
[info] Set current project to bitcoins (in build file:/home/chris/dev/bitcoins-core/)
[info] Starting scala interpreter...
[info] 
Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_92).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import org.bitcoins.core.protocol.script._
import org.bitcoins.core.protocol.script._

scala> import org.bitcoins.core.protocol.transaction._
import org.bitcoins.core.protocol.transaction._

scala> import org.bitcoins.core.script._
import org.bitcoins.core.script._

scala> import org.bitcoins.core.script.interpreter._
import org.bitcoins.core.script.interpreter._

scala> import org.bitcoins.core.policy._
import org.bitcoins.core.policy._

scala> val spendingTx = Transaction("0100000001ccf318f0cbac588a680bbad075aebdda1f211c94ba28125b0f627f9248310db3000000006b4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353ffffffff0210335d05000000001976a914b1d7591b69e9def0feb13254bace942923c7922d88ac48030000000000001976a9145e690c865c2f6f7a9710a474154ab1423abb5b9288ac00000000")
spendingTx: org.bitcoins.core.protocol.transaction.Transaction = TransactionImpl(1,List(TransactionInputImpl(TransactionOutPointImpl(b30d3148927f620f5b1228ba941c211fdabdae75d0ba0b688a58accbf018f3cc,0),P2PKHScriptSignatureImpl(4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353,List(BytesToPushOntoStackImpl(72), ScriptConstantImpl(30450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01), BytesToPushOntoStackImpl(33), ScriptConstantImpl(0241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353))),4294967295)),List(TransactionOutputImpl(8...
scala> val scriptPubKey = ScriptPubKey("76a91431a420903c05a0a7de2de40c9f02ebedbacdc17288ac")
scriptPubKey: org.bitcoins.core.protocol.script.ScriptPubKey = P2PKHScriptPubKeyImpl(76a91431a420903c05a0a7de2de40c9f02ebedbacdc17288ac,List(OP_DUP, OP_HASH160, BytesToPushOntoStackImpl(20), ScriptConstantImpl(31a420903c05a0a7de2de40c9f02ebedbacdc172), OP_EQUALVERIFY, OP_CHECKSIG))

scala> val inputIndex = 0
inputIndex: Int = 0

scala> val program = ScriptProgram(spendingTx,scriptPubKey,inputIndex, Policy.standardScriptVerifyFlags)
program: org.bitcoins.core.script.PreExecutionScriptProgram = PreExecutionScriptProgramImpl(TransactionSignatureComponentImpl(TransactionImpl(1,List(TransactionInputImpl(TransactionOutPointImpl(b30d3148927f620f5b1228ba941c211fdabdae75d0ba0b688a58accbf018f3cc,0),P2PKHScriptSignatureImpl(4830450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01210241d746ca08da0a668735c3e01c1fa02045f2f399c5937079b6434b5a31dfe353,List(BytesToPushOntoStackImpl(72), ScriptConstantImpl(30450221008337ce3ce0c6ac0ab72509f889c1d52701817a2362d6357457b63e3bdedc0c0602202908963b9cf1a095ab3b34b95ce2bc0d67fb0f19be1cc5f7b3de0b3a325629bf01), BytesToPushOntoStackImpl(33), ScriptConstantImpl(0241d746ca08da0a668735c3e01c1fa02045f2f399c5937079...
scala> ScriptInterpreter.run(program)
res0: org.bitcoins.core.script.result.ScriptResult = ScriptOk

Running tests

To run the entire test suite all you need to do is run the following command

chris@chris:~/dev/bitcoins-core$ sbt test
[info] Run completed in 8 seconds, 805 milliseconds.
[info] Total number of tests run: 613
[info] Suites: completed 91, aborted 0
[info] Tests: succeeded 613, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
[success] Total time: 17 s, completed May 7, 2016 1:11:34 PM
chris@chris:~/dev/bitcoins-core$ 

To run a specific suite of tests you can specify the suite name in the following way

chris@chris:~/dev/bitcoins-core$ sbt
> test-only *ScriptInterpreterTest*
[info] ScriptInterpreterTest:
[info] ScriptInterpreter
[info] - must evaluate all the scripts from the bitcoin core script_tests.json
[info] Run completed in 8 seconds, 208 milliseconds.
[info] Total number of tests run: 1
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
>