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Pass a FilteredTransaction instead of a Signed transaction to a non-validating notary flow to preserve privacy.

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This also means that the non-validating notary can service requests on the network without loading any custom plugins.
This commit is contained in:
Andrius Dagys 2017-02-08 17:11:00 +00:00
parent 98c30f6432
commit a19dd55257
8 changed files with 117 additions and 70 deletions
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8
core/src/main/kotlin/net/corda/core/node/services/NetworkMapCache.kt
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@ -5,11 +5,9 @@ import com.google.common.util.concurrent.ListenableFuture
import net.corda.core.contracts.Contract
import net.corda.core.crypto.CompositeKey
import net.corda.core.crypto.Party
import net.corda.core.messaging.MessageRecipients
import net.corda.core.messaging.MessagingService
import net.corda.core.messaging.SingleMessageRecipient
import net.corda.core.node.NodeInfo
import net.corda.core.node.ServiceEntry
import net.corda.core.randomOrNull
import rx.Observable
@ -73,6 +71,7 @@ interface NetworkMapCache {
/** Look up the node info for a specific peer key. */
fun getNodeByLegalIdentityKey(compositeKey: CompositeKey): NodeInfo?
/** Look up all nodes advertising the service owned by [compositeKey] */
fun getNodesByAdvertisedServiceIdentityKey(compositeKey: CompositeKey): List<NodeInfo> {
return partyNodes.filter { it.advertisedServices.any { it.identity.owningKey == compositeKey } }
@ -108,6 +107,11 @@ interface NetworkMapCache {
/** Checks whether a given party is an advertised notary identity */
fun isNotary(party: Party): Boolean = notaryNodes.any { it.notaryIdentity == party }
/** Checks whether a given party is an advertised validating notary identity */
fun isValidatingNotary(party: Party): Boolean {
return notaryNodes.any { it.notaryIdentity == party && it.advertisedServices.any { it.info.type.isValidatingNotary() }}
}
/**
* Add a network map service; fetches a copy of the latest map from the service and subscribes to any further
* updates.

1
core/src/main/kotlin/net/corda/core/node/services/ServiceType.kt
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@ -43,6 +43,7 @@ sealed class ServiceType(val id: String) {
fun isSubTypeOf(superType: ServiceType) = (id == superType.id) || id.startsWith(superType.id + ".")
fun isNotary() = isSubTypeOf(notary)
fun isValidatingNotary() = isNotary() && id.contains(".validating")
override fun hashCode(): Int = id.hashCode()
override fun toString(): String = id.toString()

29
core/src/main/kotlin/net/corda/flows/NonValidatingNotaryFlow.kt Normal file
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@ -0,0 +1,29 @@
package net.corda.flows
import co.paralleluniverse.fibers.Suspendable
import net.corda.core.crypto.Party
import net.corda.core.node.services.TimestampChecker
import net.corda.core.node.services.UniquenessProvider
import net.corda.core.transactions.FilteredTransaction
import net.corda.core.utilities.unwrap
class NonValidatingNotaryFlow(otherSide: Party,
timestampChecker: TimestampChecker,
uniquenessProvider: UniquenessProvider) : NotaryFlow.Service(otherSide, timestampChecker, uniquenessProvider) {
/**
* The received transaction is not checked for contract-validity, as that would require fully
* resolving it into a [TransactionForVerification], for which the caller would have to reveal the whole transaction
* history chain.
* As a result, the Notary _will commit invalid transactions_ as well, but as it also records the identity of
* the caller, it is possible to raise a dispute and verify the validity of the transaction and subsequently
* undo the commit of the input states (the exact mechanism still needs to be worked out).
*/
@Suspendable
override fun receiveAndVerifyTx(): NotaryFlow.Service.TransactionParts {
val ftx = receive<FilteredTransaction>(otherSide).unwrap {
it.verify()
it
}
return TransactionParts(ftx.rootHash, ftx.filteredLeaves.inputs, ftx.filteredLeaves.timestamp)
}
}

100
core/src/main/kotlin/net/corda/flows/NotaryFlow.kt
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@ -1,10 +1,9 @@
package net.corda.flows
import co.paralleluniverse.fibers.Suspendable
import net.corda.core.crypto.DigitalSignature
import net.corda.core.crypto.Party
import net.corda.core.crypto.SignedData
import net.corda.core.crypto.signWithECDSA
import net.corda.core.contracts.StateRef
import net.corda.core.contracts.Timestamp
import net.corda.core.crypto.*
import net.corda.core.flows.FlowException
import net.corda.core.flows.FlowLogic
import net.corda.core.node.services.TimestampChecker
@ -12,13 +11,12 @@ import net.corda.core.node.services.UniquenessException
import net.corda.core.node.services.UniquenessProvider
import net.corda.core.serialization.serialize
import net.corda.core.transactions.SignedTransaction
import net.corda.core.transactions.WireTransaction
import net.corda.core.utilities.ProgressTracker
import net.corda.core.utilities.unwrap
object NotaryFlow {
/**
* A flow to be used for obtaining a signature from a [NotaryService] ascertaining the transaction
* A flow to be used by a party for obtaining a signature from a [NotaryService] ascertaining the transaction
* timestamp is correct and none of its inputs have been used in another completed transaction.
*
* @throws NotaryException in case the any of the inputs to the transaction have been consumed
@ -52,8 +50,14 @@ object NotaryFlow {
throw NotaryException(NotaryError.SignaturesMissing(ex))
}
val payload: Any = if (serviceHub.networkMapCache.isValidatingNotary(notaryParty)) {
stx
} else {
wtx.buildFilteredTransaction { it is StateRef || it is Timestamp }
}
val response = try {
sendAndReceive<DigitalSignature.WithKey>(notaryParty, SignRequest(stx))
sendAndReceive<DigitalSignature.WithKey>(notaryParty, payload)
} catch (e: NotaryException) {
if (e.error is NotaryError.Conflict) {
e.error.conflict.verified()
@ -73,64 +77,64 @@ object NotaryFlow {
}
}
/**
* Checks that the timestamp command is valid (if present) and commits the input state, or returns a conflict
* A flow run by a notary service that handles notarisation requests.
*
* It checks that the timestamp command is valid (if present) and commits the input state, or returns a conflict
* if any of the input states have been previously committed.
*
* Extend this class, overriding _beforeCommit_ to add custom transaction processing/validation logic.
*
* TODO: the notary service should only be able to see timestamp commands and inputs
* Additional transaction validation logic can be added when implementing [receiveAndVerifyTx].
*/
open class Service(val otherSide: Party,
val timestampChecker: TimestampChecker,
val uniquenessProvider: UniquenessProvider) : FlowLogic<Unit>() {
abstract class Service(val otherSide: Party,
val timestampChecker: TimestampChecker,
val uniquenessProvider: UniquenessProvider) : FlowLogic<Unit>() {
@Suspendable
override fun call() {
val stx = receive<SignRequest>(otherSide).unwrap { it.tx }
val wtx = stx.tx
validateTimestamp(wtx)
beforeCommit(stx)
commitInputStates(wtx)
val sig = sign(stx.id.bytes)
send(otherSide, sig)
}
private fun validateTimestamp(tx: WireTransaction) {
if (tx.timestamp != null
&& !timestampChecker.isValid(tx.timestamp))
throw NotaryException(NotaryError.TimestampInvalid())
val (id, inputs, timestamp) = receiveAndVerifyTx()
validateTimestamp(timestamp)
commitInputStates(inputs, id)
signAndSendResponse(id)
}
/**
* No pre-commit processing is done. Transaction is not checked for contract-validity, as that would require fully
* resolving it into a [TransactionForVerification], for which the caller would have to reveal the whole transaction
* history chain.
* As a result, the Notary _will commit invalid transactions_ as well, but as it also records the identity of
* the caller, it is possible to raise a dispute and verify the validity of the transaction and subsequently
* undo the commit of the input states (the exact mechanism still needs to be worked out).
* Implement custom logic to receive the transaction to notarise, and perform verification based on validity and
* privacy requirements.
*/
@Suspendable
open fun beforeCommit(stx: SignedTransaction) {
abstract fun receiveAndVerifyTx(): TransactionParts
/**
* The minimum amount of information needed to notarise a transaction. Note that this does not include
* any sensitive transaction details.
*/
data class TransactionParts(val id: SecureHash, val inputs: List<StateRef>, val timestamp: Timestamp?)
@Suspendable
private fun signAndSendResponse(txId: SecureHash) {
val sig = sign(txId.bytes)
send(otherSide, sig)
}
private fun validateTimestamp(t: Timestamp?) {
if (t != null && !timestampChecker.isValid(t))
throw NotaryException(NotaryError.TimestampInvalid())
}
/**
* A NotaryException is thrown if any of the states have been consumed by a different transaction. Note that
* this method does not throw an exception when input states are present multiple times within the transaction.
*/
private fun commitInputStates(tx: WireTransaction) {
private fun commitInputStates(inputs: List<StateRef>, txId: SecureHash) {
try {
uniquenessProvider.commit(tx.inputs, tx.id, otherSide)
uniquenessProvider.commit(inputs, txId, otherSide)
} catch (e: UniquenessException) {
val conflicts = tx.inputs.filterIndexed { i, stateRef ->
val conflicts = inputs.filterIndexed { i, stateRef ->
val consumingTx = e.error.stateHistory[stateRef]
consumingTx != null && consumingTx != UniquenessProvider.ConsumingTx(tx.id, i, otherSide)
consumingTx != null && consumingTx != UniquenessProvider.ConsumingTx(txId, i, otherSide)
}
if (conflicts.isNotEmpty()) {
// TODO: Create a new UniquenessException that only contains the conflicts filtered above.
throw notaryException(tx, e)
throw notaryException(txId, e)
}
}
}
@ -140,14 +144,12 @@ object NotaryFlow {
return mySigningKey.signWithECDSA(bits)
}
private fun notaryException(tx: WireTransaction, e: UniquenessException): NotaryException {
private fun notaryException(txId: SecureHash, e: UniquenessException): NotaryException {
val conflictData = e.error.serialize()
val signedConflict = SignedData(conflictData, sign(conflictData.bytes))
return NotaryException(NotaryError.Conflict(tx, signedConflict))
return NotaryException(NotaryError.Conflict(txId, signedConflict))
}
}
data class SignRequest(val tx: SignedTransaction)
}
class NotaryException(val error: NotaryError) : FlowException() {
@ -155,15 +157,15 @@ class NotaryException(val error: NotaryError) : FlowException() {
}
sealed class NotaryError {
class Conflict(val tx: WireTransaction, val conflict: SignedData<UniquenessProvider.Conflict>) : NotaryError() {
override fun toString() = "One or more input states for transaction ${tx.id} have been used in another transaction"
class Conflict(val txId: SecureHash, val conflict: SignedData<UniquenessProvider.Conflict>) : NotaryError() {
override fun toString() = "One or more input states for transaction $txId have been used in another transaction"
}
/** Thrown if the time specified in the timestamp command is outside the allowed tolerance */
class TimestampInvalid : NotaryError()
class TransactionInvalid(val msg: String) : NotaryError()
class SignaturesInvalid(val msg: String): NotaryError()
class SignaturesInvalid(val msg: String) : NotaryError()
class SignaturesMissing(val cause: SignedTransaction.SignaturesMissingException) : NotaryError() {
override fun toString() = cause.toString()

42
core/src/main/kotlin/net/corda/flows/ValidatingNotaryFlow.kt
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@ -7,6 +7,7 @@ import net.corda.core.node.services.TimestampChecker
import net.corda.core.node.services.UniquenessProvider
import net.corda.core.transactions.SignedTransaction
import net.corda.core.transactions.WireTransaction
import net.corda.core.utilities.unwrap
import java.security.SignatureException
/**
@ -19,21 +20,18 @@ class ValidatingNotaryFlow(otherSide: Party,
timestampChecker: TimestampChecker,
uniquenessProvider: UniquenessProvider) :
NotaryFlow.Service(otherSide, timestampChecker, uniquenessProvider) {
/**
* The received transaction is checked for contract-validity, which requires fully resolving it into a
* [TransactionForVerification], for which the caller also has to to reveal the whole transaction
* dependency chain.
*/
@Suspendable
override fun beforeCommit(stx: SignedTransaction) {
try {
checkSignatures(stx)
val wtx = stx.tx
resolveTransaction(wtx)
wtx.toLedgerTransaction(serviceHub).verify()
} catch (e: Exception) {
when (e) {
is TransactionVerificationException -> NotaryException(NotaryError.TransactionInvalid(e.toString()))
is SignatureException -> throw NotaryException(NotaryError.SignaturesInvalid(e.toString()))
else -> throw e
}
}
override fun receiveAndVerifyTx(): TransactionParts {
val stx = receive<SignedTransaction>(otherSide).unwrap { it }
checkSignatures(stx)
val wtx = stx.tx
validateTransaction(wtx)
return TransactionParts(wtx.id, wtx.inputs, wtx.timestamp)
}
private fun checkSignatures(stx: SignedTransaction) {
@ -45,7 +43,19 @@ class ValidatingNotaryFlow(otherSide: Party,
}
@Suspendable
private fun resolveTransaction(wtx: WireTransaction) {
subFlow(ResolveTransactionsFlow(wtx, otherSide))
fun validateTransaction(wtx: WireTransaction) {
try {
resolveTransaction(wtx)
wtx.toLedgerTransaction(serviceHub).verify()
} catch (e: Exception) {
throw when (e) {
is TransactionVerificationException -> NotaryException(NotaryError.TransactionInvalid(e.toString()))
is SignatureException -> NotaryException(NotaryError.SignaturesInvalid(e.toString()))
else -> e
}
}
}
@Suspendable
private fun resolveTransaction(wtx: WireTransaction) = subFlow(ResolveTransactionsFlow(wtx, otherSide))
}

2
node/src/integration-test/kotlin/net/corda/node/services/RaftNotaryServiceTests.kt
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@ -53,7 +53,7 @@ class RaftNotaryServiceTests : NodeBasedTest() {
val ex = assertFailsWith(NotaryException::class) { secondSpend.resultFuture.getOrThrow() }
val error = ex.error as NotaryError.Conflict
assertEquals(error.tx, secondSpendTx.tx)
assertEquals(error.txId, secondSpendTx.id)
}
private fun issueState(node: AbstractNode, notary: Party, notaryKey: KeyPair): StateAndRef<*> {

3
node/src/main/kotlin/net/corda/node/services/transactions/SimpleNotaryService.kt
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@ -4,6 +4,7 @@ import net.corda.core.crypto.Party
import net.corda.core.node.services.ServiceType
import net.corda.core.node.services.TimestampChecker
import net.corda.core.node.services.UniquenessProvider
import net.corda.flows.NonValidatingNotaryFlow
import net.corda.flows.NotaryFlow
import net.corda.node.services.api.ServiceHubInternal
@ -16,6 +17,6 @@ class SimpleNotaryService(services: ServiceHubInternal,
}
override fun createFlow(otherParty: Party): NotaryFlow.Service {
return NotaryFlow.Service(otherParty, timestampChecker, uniquenessProvider)
return NonValidatingNotaryFlow(otherParty, timestampChecker, uniquenessProvider)
}
}

2
node/src/test/kotlin/net/corda/node/services/NotaryServiceTests.kt
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@ -128,7 +128,7 @@ class NotaryServiceTests {
val ex = assertFailsWith(NotaryException::class) { future.resultFuture.getOrThrow() }
val notaryError = ex.error as NotaryError.Conflict
assertEquals(notaryError.tx, stx2.tx)
assertEquals(notaryError.txId, stx2.id)
notaryError.conflict.verified()
}