Added new project core.

Project Contracts depends only on core.

.gitignore

@@ -4,6 +4,8 @@ TODO
 
 .gradle
 /build/
+/contracts/build
+/core/build
 /docs/build/doctrees
 
 buyer
@@ -62,5 +64,4 @@ atlassian-ide-plugin.xml
 # Crashlytics plugin (for Android Studio and IntelliJ)
 com_crashlytics_export_strings.xml
 crashlytics.properties
-crashlytics-build.properties
-
+crashlytics-build.properties

build.gradle

@@ -55,6 +55,8 @@ configurations.all() {
 dependencies {
     testCompile 'junit:junit:4.12'
 
+    compile project(':contracts')
+
     compile "com.google.code.findbugs:jsr305:3.0.1"
     compile "org.slf4j:slf4j-jdk14:1.7.13"
 

contracts/build.gradle

@@ -70,5 +70,5 @@ repositories {
 }
 
 dependencies {
-    compile rootProject
+    compile project(':core')
 }

contracts/src/main/kotlin/contracts/CommercialPaper.kt

@@ -1,160 +0,0 @@
-/*
- * Copyright 2015 Distributed Ledger Group LLC.  Distributed as Licensed Company IP to DLG Group Members
- * pursuant to the August 7, 2015 Advisory Services Agreement and subject to the Company IP License terms
- * set forth therein.
- *
- * All other rights reserved.
- */
-
-package contracts
-
-import core.*
-import core.crypto.NullPublicKey
-import core.crypto.SecureHash
-import core.crypto.toStringShort
-import core.utilities.Emoji
-import java.security.PublicKey
-import java.time.Instant
-
-/**
- * This is an ultra-trivial implementation of commercial paper, which is essentially a simpler version of a corporate
- * bond. It can be seen as a company-specific currency. A company issues CP with a particular face value, say $100,
- * but sells it for less, say $90. The paper can be redeemed for cash at a given date in the future. Thus this example
- * would have a 10% interest rate with a single repayment. Commercial paper is often rolled over (the maturity date
- * is adjusted as if the paper was redeemed and immediately repurchased, but without having to front the cash).
- *
- * This contract is not intended to realistically model CP. It is here only to act as a next step up above cash in
- * the prototyping phase. It is thus very incomplete.
- *
- * Open issues:
- *  - In this model, you cannot merge or split CP. Can you do this normally? We could model CP as a specialised form
- *    of cash, or reuse some of the cash code? Waiting on response from Ayoub and Rajar about whether CP can always
- *    be split/merged or only in secondary markets. Even if current systems can't do this, would it be a desirable
- *    feature to have anyway?
- *  - The funding steps of CP is totally ignored in this model.
- *  - No attention is paid to the existing roles of custodians, funding banks, etc.
- *  - There are regional variations on the CP concept, for instance, American CP requires a special "CUSIP number"
- *    which may need to be tracked. That, in turn, requires validation logic (there is a bean validator that knows how
- *    to do this in the Apache BVal project).
- */
-
-val CP_PROGRAM_ID = SecureHash.sha256("replace-me-later-with-bytecode-hash")
-
-// TODO: Generalise the notion of an owned instrument into a superclass/supercontract. Consider composition vs inheritance.
-class CommercialPaper : Contract {
-    // TODO: should reference the content of the legal agreement, not its URI
-    override val legalContractReference: SecureHash = SecureHash.sha256("https://en.wikipedia.org/wiki/Commercial_paper")
-
-    data class State(
-            val issuance: PartyReference,
-            override val owner: PublicKey,
-            val faceValue: Amount,
-            val maturityDate: Instant
-    ) : OwnableState, ICommercialPaperState {
-        override val programRef = CP_PROGRAM_ID
-
-        fun withoutOwner() = copy(owner = NullPublicKey)
-        override fun withNewOwner(newOwner: PublicKey) = Pair(Commands.Move(), copy(owner = newOwner))
-        override fun toString() = "${Emoji.newspaper}CommercialPaper(of $faceValue redeemable on $maturityDate by '$issuance', owned by ${owner.toStringShort()})"
-
-        // Although kotlin is smart enough not to need these, as we are using the ICommercialPaperState, we need to declare them explicitly for use later,
-        override fun withOwner(newOwner: PublicKey): ICommercialPaperState = copy(owner = newOwner)
-        override fun withIssuance(newIssuance: PartyReference): ICommercialPaperState = copy(issuance = newIssuance)
-        override fun withFaceValue(newFaceValue: Amount): ICommercialPaperState = copy(faceValue = newFaceValue)
-        override fun withMaturityDate(newMaturityDate: Instant): ICommercialPaperState = copy(maturityDate = newMaturityDate)
-    }
-
-    interface Commands : CommandData {
-        class Move : TypeOnlyCommandData(), Commands
-        class Redeem : TypeOnlyCommandData(), Commands
-        // We don't need a nonce in the issue command, because the issuance.reference field should already be unique per CP.
-        // However, nothing in the platform enforces that uniqueness: it's up to the issuer.
-        class Issue : TypeOnlyCommandData(), Commands
-    }
-
-    override fun verify(tx: TransactionForVerification) {
-        // Group by everything except owner: any modification to the CP at all is considered changing it fundamentally.
-        val groups = tx.groupStates<State>() { it.withoutOwner() }
-
-        // There are two possible things that can be done with this CP. The first is trading it. The second is redeeming
-        // it for cash on or after the maturity date.
-        val command = tx.commands.requireSingleCommand<CommercialPaper.Commands>()
-        val timestamp: TimestampCommand? = tx.getTimestampBy(DummyTimestampingAuthority.identity)
-
-        for (group in groups) {
-            when (command.value) {
-                is Commands.Move -> {
-                    val input = group.inputs.single()
-                    requireThat {
-                        "the transaction is signed by the owner of the CP" by (command.signers.contains(input.owner))
-                        "the state is propagated" by (group.outputs.size == 1)
-                    }
-                }
-
-                is Commands.Redeem -> {
-                    val input = group.inputs.single()
-                    val received = tx.outStates.sumCashBy(input.owner)
-                    val time = timestamp?.after ?: throw IllegalArgumentException("Redemptions must be timestamped")
-                    requireThat {
-                        "the paper must have matured" by (time > input.maturityDate)
-                        "the received amount equals the face value" by (received == input.faceValue)
-                        "the paper must be destroyed" by group.outputs.isEmpty()
-                        "the transaction is signed by the owner of the CP" by (command.signers.contains(input.owner))
-                    }
-                }
-
-                is Commands.Issue -> {
-                    val output = group.outputs.single()
-                    val time = timestamp?.before ?: throw IllegalArgumentException("Issuances must be timestamped")
-                    requireThat {
-                        // Don't allow people to issue commercial paper under other entities identities.
-                        "the issuance is signed by the claimed issuer of the paper" by
-                                (command.signers.contains(output.issuance.party.owningKey))
-                        "the face value is not zero" by (output.faceValue.pennies > 0)
-                        "the maturity date is not in the past" by (time < output.maturityDate)
-                        // Don't allow an existing CP state to be replaced by this issuance.
-                        "there is no input state" by group.inputs.isEmpty()
-                    }
-                }
-
-            // TODO: Think about how to evolve contracts over time with new commands.
-                else -> throw IllegalArgumentException("Unrecognised command")
-            }
-        }
-    }
-
-    /**
-     * Returns a transaction that issues commercial paper, owned by the issuing parties key. Does not update
-     * an existing transaction because you aren't able to issue multiple pieces of CP in a single transaction
-     * at the moment: this restriction is not fundamental and may be lifted later.
-     */
-    fun generateIssue(issuance: PartyReference, faceValue: Amount, maturityDate: Instant): TransactionBuilder {
-        val state = State(issuance, issuance.party.owningKey, faceValue, maturityDate)
-        return TransactionBuilder().withItems(state, Command(Commands.Issue(), issuance.party.owningKey))
-    }
-
-    /**
-     * Updates the given partial transaction with an input/output/command to reassign ownership of the paper.
-     */
-    fun generateMove(tx: TransactionBuilder, paper: StateAndRef<State>, newOwner: PublicKey) {
-        tx.addInputState(paper.ref)
-        tx.addOutputState(paper.state.copy(owner = newOwner))
-        tx.addCommand(Commands.Move(), paper.state.owner)
-    }
-
-    /**
-     * Intended to be called by the issuer of some commercial paper, when an owner has notified us that they wish
-     * to redeem the paper. We must therefore send enough money to the key that owns the paper to satisfy the face
-     * value, and then ensure the paper is removed from the ledger.
-     *
-     * @throws InsufficientBalanceException if the wallet doesn't contain enough money to pay the redeemer
-     */
-    @Throws(InsufficientBalanceException::class)
-    fun generateRedeem(tx: TransactionBuilder, paper: StateAndRef<State>, wallet: List<StateAndRef<Cash.State>>) {
-        // Add the cash movement using the states in our wallet.
-        Cash().generateSpend(tx, paper.state.faceValue, paper.state.owner, wallet)
-        tx.addInputState(paper.ref)
-        tx.addCommand(CommercialPaper.Commands.Redeem(), paper.state.owner)
-    }
-}
-

core/build.gradle

@@ -0,0 +1,23 @@
+group 'com.r3cev.prototyping'
+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+apply plugin: 'kotlin'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-test:$kotlin_version"
+
+    compile "org.slf4j:slf4j-jdk14:1.7.13"
+
+    compile("com.google.guava:guava:19.0")
+
+    // Quasar: for the bytecode rewriting for state machines.
+    compile("co.paralleluniverse:quasar-core:${quasar_version}:jdk8")
+//    quasar("co.paralleluniverse:quasar-core:${quasar_version}:jdk8@jar")
+}

core/src/main/kotlin/core/IndentityService.kt

@@ -0,0 +1,13 @@
+package core
+
+import core.Party
+import java.security.PublicKey
+
+/**
+ * An identity service maintains an bidirectional map of [Party]s to their associated public keys and thus supports
+ * lookup of a party given its key. This is obviously very incomplete and does not reflect everything a real identity
+ * service would provide.
+ */
+interface IdentityService {
+    fun partyFromKey(key: PublicKey): Party?
+}

core/src/main/kotlin/core/TimestamperService.kt

@@ -0,0 +1,29 @@
+package core
+
+import co.paralleluniverse.fibers.Suspendable
+import core.crypto.DigitalSignature
+import core.crypto.generateKeyPair
+import core.serialization.SerializedBytes
+
+/**
+ * Simple interface (for testing) to an abstract timestamping service. Note that this is not "timestamping" in the
+ * blockchain sense of a total ordering of transactions, but rather, a signature from a well known/trusted timestamping
+ * service over a transaction that indicates the timestamp in it is accurate. Such a signature may not always be
+ * necessary: if there are multiple parties involved in a transaction then they can cross-check the timestamp
+ * themselves.
+ */
+interface TimestamperService {
+    @Suspendable
+    fun timestamp(wtxBytes: SerializedBytes<WireTransaction>): DigitalSignature.LegallyIdentifiable
+
+    /** The name+pubkey that this timestamper will sign with. */
+    val identity: Party
+}
+
+// Smart contracts may wish to specify explicitly which timestamping authorities are trusted to assert the time.
+// We define a dummy authority here to allow to us to develop prototype contracts in the absence of a real authority.
+// The timestamper itself is implemented in the unit test part of the code (in TestUtils.kt).
+object DummyTimestampingAuthority {
+    val key = generateKeyPair()
+    val identity = Party("The dummy timestamper", key.public)
+}

core/src/main/kotlin/core/TransactionVerification.kt

@@ -0,0 +1,139 @@
+/*
+ * Copyright 2015 Distributed Ledger Group LLC.  Distributed as Licensed Company IP to DLG Group Members
+ * pursuant to the August 7, 2015 Advisory Services Agreement and subject to the Company IP License terms
+ * set forth therein.
+ *
+ * All other rights reserved.
+ */
+
+package core
+
+import core.crypto.SecureHash
+import java.util.*
+
+class TransactionResolutionException(val hash: SecureHash) : Exception()
+class TransactionConflictException(val conflictRef: StateRef, val tx1: LedgerTransaction, val tx2: LedgerTransaction) : Exception()
+
+/**
+ * A TransactionGroup defines a directed acyclic graph of transactions that can be resolved with each other and then
+ * verified. Successful verification does not imply the non-existence of other conflicting transactions: simply that
+ * this subgraph does not contain conflicts and is accepted by the involved contracts.
+ *
+ * The inputs of the provided transactions must be resolvable either within the [transactions] set, or from the
+ * [nonVerifiedRoots] set. Transactions in the non-verified set are ignored other than for looking up input states.
+ */
+class TransactionGroup(val transactions: Set<LedgerTransaction>, val nonVerifiedRoots: Set<LedgerTransaction>) {
+
+    /**
+     * Verifies the group and returns the set of resolved transactions.
+     */
+    fun verify(programMap: ContractFactory): Set<TransactionForVerification> {
+        // Check that every input can be resolved to an output.
+        // Check that no output is referenced by more than one input.
+        // Cycles should be impossible due to the use of hashes as pointers.
+        check(transactions.intersect(nonVerifiedRoots).isEmpty())
+
+        val hashToTXMap: Map<SecureHash, List<LedgerTransaction>> = (transactions + nonVerifiedRoots).groupBy { it.hash }
+        val refToConsumingTXMap = hashMapOf<StateRef, LedgerTransaction>()
+
+        val resolved = HashSet<TransactionForVerification>(transactions.size)
+        for (tx in transactions) {
+            val inputs = ArrayList<ContractState>(tx.inputs.size)
+            for (ref in tx.inputs) {
+                val conflict = refToConsumingTXMap[ref]
+                if (conflict != null)
+                    throw TransactionConflictException(ref, tx, conflict)
+                refToConsumingTXMap[ref] = tx
+
+                // Look up the connecting transaction.
+                val ltx = hashToTXMap[ref.txhash]?.single() ?: throw TransactionResolutionException(ref.txhash)
+                // Look up the output in that transaction by index.
+                inputs.add(ltx.outputs[ref.index])
+            }
+            resolved.add(TransactionForVerification(inputs, tx.outputs, tx.commands, tx.hash))
+        }
+
+        for (tx in resolved)
+            tx.verify(programMap)
+        return resolved
+    }
+
+}
+
+/** A transaction in fully resolved and sig-checked form, ready for passing as input to a verification function. */
+data class TransactionForVerification(val inStates: List<ContractState>,
+                                      val outStates: List<ContractState>,
+                                      val commands: List<AuthenticatedObject<CommandData>>,
+                                      val origHash: SecureHash) {
+    override fun hashCode() = origHash.hashCode()
+    override fun equals(other: Any?) = other is TransactionForVerification && other.origHash == origHash
+
+    /**
+     * @throws TransactionVerificationException if a contract throws an exception, the original is in the cause field
+     * @throws IllegalStateException if a state refers to an unknown contract.
+     */
+    @Throws(TransactionVerificationException::class, IllegalStateException::class)
+    fun verify(programMap: ContractFactory) {
+        // For each input and output state, locate the program to run. Then execute the verification function. If any
+        // throws an exception, the entire transaction is invalid.
+        val programHashes = (inStates.map { it.programRef } + outStates.map { it.programRef }).toSet()
+        for (hash in programHashes) {
+            val program: Contract = programMap[hash]
+            try {
+                program.verify(this)
+            } catch(e: Throwable) {
+                throw TransactionVerificationException(this, program, e)
+            }
+        }
+    }
+
+    /**
+     * Utilities for contract writers to incorporate into their logic.
+     */
+
+    data class InOutGroup<T : ContractState>(val inputs: List<T>, val outputs: List<T>)
+
+    // A shortcut to make IDE auto-completion more intuitive for Java users.
+    fun getTimestampBy(timestampingAuthority: Party): TimestampCommand? = commands.getTimestampBy(timestampingAuthority)
+
+    // For Java users.
+    fun <T : ContractState> groupStates(ofType: Class<T>, selector: (T) -> Any): List<InOutGroup<T>> {
+        val inputs = inStates.filterIsInstance(ofType)
+        val outputs = outStates.filterIsInstance(ofType)
+
+        val inGroups = inputs.groupBy(selector)
+        val outGroups = outputs.groupBy(selector)
+
+        @Suppress("DEPRECATION")
+        return groupStatesInternal(inGroups, outGroups)
+    }
+
+    // For Kotlin users: this version has nicer syntax and avoids reflection/object creation for the lambda.
+    inline fun <reified T : ContractState> groupStates(selector: (T) -> Any): List<InOutGroup<T>> {
+        val inputs = inStates.filterIsInstance<T>()
+        val outputs = outStates.filterIsInstance<T>()
+
+        val inGroups = inputs.groupBy(selector)
+        val outGroups = outputs.groupBy(selector)
+
+        @Suppress("DEPRECATION")
+        return groupStatesInternal(inGroups, outGroups)
+    }
+
+    @Deprecated("Do not use this directly: exposed as public only due to function inlining")
+    fun <T : ContractState> groupStatesInternal(inGroups: Map<Any, List<T>>, outGroups: Map<Any, List<T>>): List<InOutGroup<T>> {
+        val result = ArrayList<InOutGroup<T>>()
+
+        for ((k, v) in inGroups.entries)
+            result.add(InOutGroup(v, outGroups[k] ?: emptyList()))
+        for ((k, v) in outGroups.entries) {
+            if (inGroups[k] == null)
+                result.add(InOutGroup(emptyList(), v))
+        }
+
+        return result
+    }
+}
+
+/** Thrown if a verification fails due to a contract rejection. */
+class TransactionVerificationException(val tx: TransactionForVerification, val contract: Contract, cause: Throwable?) : Exception(cause)

core/src/main/kotlin/core/node/TimestampingError.kt

@@ -0,0 +1,15 @@
+package core.node
+
+sealed class TimestampingError : Exception() {
+    class RequiresExactlyOneCommand : TimestampingError()
+    /**
+     * Thrown if an attempt is made to timestamp a transaction using a trusted timestamper, but the time on the
+     * transaction is too far in the past or future relative to the local clock and thus the timestamper would reject
+     * it.
+     */
+    class NotOnTimeException : TimestampingError()
+
+    /** Thrown if the command in the transaction doesn't list this timestamping authorities public key as a signer */
+    class NotForMe : TimestampingError()
+}
+

settings.gradle

@@ -1,2 +1,3 @@
 rootProject.name = 'r3prototyping'
-include 'contracts'
+include 'contracts'
+include 'core'

src/main/kotlin/core/Services.kt

@@ -64,30 +64,6 @@ interface KeyManagementService {
     fun freshKey(): KeyPair
 }
 
-/**
- * An identity service maintains an bidirectional map of [Party]s to their associated public keys and thus supports
- * lookup of a party given its key. This is obviously very incomplete and does not reflect everything a real identity
- * service would provide.
- */
-interface IdentityService {
-    fun partyFromKey(key: PublicKey): Party?
-}
-
-/**
- * Simple interface (for testing) to an abstract timestamping service. Note that this is not "timestamping" in the
- * blockchain sense of a total ordering of transactions, but rather, a signature from a well known/trusted timestamping
- * service over a transaction that indicates the timestamp in it is accurate. Such a signature may not always be
- * necessary: if there are multiple parties involved in a transaction then they can cross-check the timestamp
- * themselves.
- */
-interface TimestamperService {
-    @Suspendable
-    fun timestamp(wtxBytes: SerializedBytes<WireTransaction>): DigitalSignature.LegallyIdentifiable
-
-    /** The name+pubkey that this timestamper will sign with. */
-    val identity: Party
-}
-
 // Smart contracts may wish to specify explicitly which timestamping authorities are trusted to assert the time.
 // We define a dummy authority here to allow to us to develop prototype contracts in the absence of a real authority.
 // The timestamper itself is implemented in the unit test part of the code (in TestUtils.kt).

src/main/kotlin/core/node/TimestamperNodeService.kt

@@ -31,19 +31,6 @@ class TimestampingMessages {
     data class Request(val tx: SerializedBytes<WireTransaction>, val replyTo: MessageRecipients, val replyToTopic: String)
 }
 
-sealed class TimestampingError : Exception() {
-    class RequiresExactlyOneCommand : TimestampingError()
-    /**
-     * Thrown if an attempt is made to timestamp a transaction using a trusted timestamper, but the time on the
-     * transaction is too far in the past or future relative to the local clock and thus the timestamper would reject
-     * it.
-     */
-    class NotOnTimeException : TimestampingError()
-
-    /** Thrown if the command in the transaction doesn't list this timestamping authorities public key as a signer */
-    class NotForMe : TimestampingError()
-}
-
 /**
  * This class implements the server side of the timestamping protocol, using the local clock. A future version might
  * add features like checking against other NTP servers to make sure the clock hasn't drifted by too much.