diff --git a/core/src/main/kotlin/net/corda/core/flows/NotaryFlow.kt b/core/src/main/kotlin/net/corda/core/flows/NotaryFlow.kt
index 915ac30f58..5ef32b478d 100644
--- a/core/src/main/kotlin/net/corda/core/flows/NotaryFlow.kt
+++ b/core/src/main/kotlin/net/corda/core/flows/NotaryFlow.kt
@@ -8,12 +8,9 @@ import net.corda.core.contracts.TimeWindow
 import net.corda.core.crypto.SecureHash
 import net.corda.core.crypto.TransactionSignature
 import net.corda.core.identity.Party
-import net.corda.core.internal.BackpressureAwareTimedFlow
-import net.corda.core.internal.FetchDataFlow
-import net.corda.core.internal.NetworkParametersServiceInternal
+import net.corda.core.internal.*
 import net.corda.core.internal.notary.generateSignature
 import net.corda.core.internal.notary.validateSignatures
-import net.corda.core.internal.pushToLoggingContext
 import net.corda.core.transactions.*
 import net.corda.core.utilities.ProgressTracker
 import net.corda.core.utilities.UntrustworthyData
@@ -107,7 +104,7 @@ class NotaryFlow {
                 check(stx.coreTransaction is NotaryChangeWireTransaction) {
                     "Notary $notaryParty is not on the network parameter whitelist. A non-whitelisted notary can only be used for notary change transactions"
                 }
-                val historicNotary = (serviceHub.networkParametersService as NetworkParametersServiceInternal).getHistoricNotary(notaryParty)
+                val historicNotary = (serviceHub.networkParametersService as NetworkParametersStorage).getHistoricNotary(notaryParty)
                         ?: throw IllegalStateException("The notary party $notaryParty specified by transaction ${stx.id}, is not recognised as a current or historic notary.")
                 historicNotary.validating
 
diff --git a/core/src/main/kotlin/net/corda/core/flows/SendTransactionFlow.kt b/core/src/main/kotlin/net/corda/core/flows/SendTransactionFlow.kt
index 0da13b1ea9..b9a9b5b480 100644
--- a/core/src/main/kotlin/net/corda/core/flows/SendTransactionFlow.kt
+++ b/core/src/main/kotlin/net/corda/core/flows/SendTransactionFlow.kt
@@ -3,9 +3,7 @@ package net.corda.core.flows
 import co.paralleluniverse.fibers.Suspendable
 import net.corda.core.contracts.StateAndRef
 import net.corda.core.crypto.SecureHash
-import net.corda.core.internal.FetchDataFlow
-import net.corda.core.internal.RetrieveAnyTransactionPayload
-import net.corda.core.internal.readFully
+import net.corda.core.internal.*
 import net.corda.core.transactions.SignedTransaction
 import net.corda.core.utilities.unwrap
 
@@ -42,7 +40,7 @@ open class DataVendingFlow(val otherSideSession: FlowSession, val payload: Any)
 
     @Suspendable
     override fun call(): Void? {
-        // The first payload will be the transaction data, subsequent payload will be the transaction/attachment data.
+        // The first payload will be the transaction data, subsequent payload will be the transaction/attachment/network parameters data.
         var payload = payload
 
         // Depending on who called this flow, the type of the initial payload is different.
@@ -93,6 +91,10 @@ open class DataVendingFlow(val otherSideSession: FlowSession, val payload: Any)
                     serviceHub.attachments.openAttachment(it)?.open()?.readFully()
                             ?: throw FetchDataFlow.HashNotFound(it)
                 }
+                FetchDataFlow.DataType.PARAMETERS -> dataRequest.hashes.map {
+                    (serviceHub.networkParametersService as NetworkParametersStorage).lookupSigned(it)
+                            ?: throw FetchDataFlow.MissingNetworkParameters(it)
+                }
             }
         }
     }
diff --git a/core/src/main/kotlin/net/corda/core/internal/DigitalSignatureWithCert.kt b/core/src/main/kotlin/net/corda/core/internal/DigitalSignatureWithCert.kt
index c06cfe2e55..7e0312a9ff 100644
--- a/core/src/main/kotlin/net/corda/core/internal/DigitalSignatureWithCert.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/DigitalSignatureWithCert.kt
@@ -1,6 +1,8 @@
 package net.corda.core.internal
 
+import net.corda.core.contracts.NamedByHash
 import net.corda.core.crypto.DigitalSignature
+import net.corda.core.crypto.SecureHash
 import net.corda.core.crypto.SignedData
 import net.corda.core.crypto.verify
 import net.corda.core.serialization.CordaSerializable
@@ -43,7 +45,9 @@ Cert path: $fullCertPath
 
 /** Similar to [SignedData] but instead of just attaching the public key, the certificate for the key is attached instead. */
 @CordaSerializable
-class SignedDataWithCert<T : Any>(val raw: SerializedBytes<T>, val sig: DigitalSignatureWithCert) {
+class SignedDataWithCert<T : Any>(val raw: SerializedBytes<T>, val sig: DigitalSignatureWithCert): NamedByHash {
+    override val id: SecureHash get () = raw.hash
+
     fun verified(): T {
         sig.verify(raw)
         return uncheckedCast(raw.deserialize<Any>())
diff --git a/core/src/main/kotlin/net/corda/core/internal/FetchDataFlow.kt b/core/src/main/kotlin/net/corda/core/internal/FetchDataFlow.kt
index 7a0453dd1d..87ea20d428 100644
--- a/core/src/main/kotlin/net/corda/core/internal/FetchDataFlow.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/FetchDataFlow.kt
@@ -10,6 +10,7 @@ import net.corda.core.flows.FlowLogic
 import net.corda.core.flows.FlowSession
 import net.corda.core.internal.FetchDataFlow.DownloadedVsRequestedDataMismatch
 import net.corda.core.internal.FetchDataFlow.HashNotFound
+import net.corda.core.node.NetworkParameters
 import net.corda.core.serialization.CordaSerializable
 import net.corda.core.serialization.SerializationToken
 import net.corda.core.serialization.SerializeAsToken
@@ -51,6 +52,8 @@ sealed class FetchDataFlow<T : NamedByHash, in W : Any>(
 
     class HashNotFound(val requested: SecureHash) : FlowException()
 
+    class MissingNetworkParameters(val requested: SecureHash) : FlowException("Failed to fetch network parameters with hash: $requested")
+
     class IllegalTransactionRequest(val requested: SecureHash) : FlowException("Illegal attempt to request a transaction (${requested}) that is not in the transitive dependency graph of the sent transaction.")
 
     @CordaSerializable
@@ -64,11 +67,11 @@ sealed class FetchDataFlow<T : NamedByHash, in W : Any>(
 
     @CordaSerializable
     enum class DataType {
-        TRANSACTION, ATTACHMENT
+        TRANSACTION, ATTACHMENT, PARAMETERS
     }
 
     @Suspendable
-    @Throws(HashNotFound::class)
+    @Throws(HashNotFound::class, MissingNetworkParameters::class)
     override fun call(): Result<T> {
         // Load the items we have from disk and figure out which we're missing.
         val (fromDisk, toFetch) = loadWhatWeHave()
@@ -139,7 +142,7 @@ sealed class FetchDataFlow<T : NamedByHash, in W : Any>(
 }
 
 /**
- * Given a set of hashes either loads from from local storage  or requests them from the other peer. Downloaded
+ * Given a set of hashes either loads from local storage or requests them from the other peer. Downloaded
  * attachments are saved to local storage automatically.
  */
 class FetchAttachmentsFlow(requests: Set<SecureHash>,
@@ -158,10 +161,10 @@ class FetchAttachmentsFlow(requests: Set<SecureHash>,
                     } catch (e: FileAlreadyExistsException) {
                         // This can happen when another transaction will insert the same attachment during this transaction.
                         // The outcome is the same (the attachment is imported), so we can ignore this exception.
-                        logger.debug("Attachment ${attachment.id} already inserted.")
+                        logger.debug { "Attachment ${attachment.id} already inserted." }
                     }
                 } else {
-                    logger.debug("Attachment ${attachment.id} already exists, skipping.")
+                    logger.debug { "Attachment ${attachment.id} already exists, skipping." }
                 }
             }
         }
@@ -193,3 +196,28 @@ class FetchTransactionsFlow(requests: Set<SecureHash>, otherSide: FlowSession) :
 
     override fun load(txid: SecureHash): SignedTransaction? = serviceHub.validatedTransactions.getTransaction(txid)
 }
+
+/**
+ * Given a set of hashes either loads from local network parameters storage or requests them from the other peer. Downloaded
+ * network parameters are saved to local parameters storage automatically. This flow can be used only if the minimumPlatformVersion is >= 4.
+ * Nodes on lower versions won't respond to this flow.
+ */
+class FetchNetworkParametersFlow(requests: Set<SecureHash>,
+                                 otherSide: FlowSession) : FetchDataFlow<SignedDataWithCert<NetworkParameters>, SignedDataWithCert<NetworkParameters>>(requests, otherSide, DataType.PARAMETERS) {
+    override fun load(txid: SecureHash): SignedDataWithCert<NetworkParameters>? {
+        return (serviceHub.networkParametersService as NetworkParametersStorage).lookupSigned(txid)
+    }
+
+    override fun maybeWriteToDisk(downloaded: List<SignedDataWithCert<NetworkParameters>>) {
+        for (parameters in downloaded) {
+            with(serviceHub.networkParametersService as NetworkParametersStorage) {
+                if (!hasParameters(parameters.id)) {
+                    // This will perform the signature check too and throws SignatureVerificationException
+                    saveParameters(parameters)
+                } else {
+                    logger.debug { "Network parameters ${parameters.id} already exists in storage, skipping." }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/core/src/main/kotlin/net/corda/core/internal/NetworkParametersServiceInternal.kt b/core/src/main/kotlin/net/corda/core/internal/NetworkParametersServiceInternal.kt
index 7aacf46edf..4b3acb2312 100644
--- a/core/src/main/kotlin/net/corda/core/internal/NetworkParametersServiceInternal.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/NetworkParametersServiceInternal.kt
@@ -1,12 +1,44 @@
 package net.corda.core.internal
 
+import net.corda.core.crypto.SecureHash
 import net.corda.core.identity.Party
+import net.corda.core.node.NetworkParameters
 import net.corda.core.node.NotaryInfo
 import net.corda.core.node.services.NetworkParametersService
+import java.security.cert.X509Certificate
+
+interface NetworkParametersStorage : NetworkParametersService {
+    /**
+     * Return parameters epoch for the given parameters hash. Null if there are no parameters for this hash in the storage and we are unable to
+     * get them from network map.
+     */
+    fun getEpochFromHash(hash: SecureHash): Int?
+
+    /**
+     * Return signed network parameters with certificate for the given hash. Null if there are no parameters for this hash in the storage.
+     * (No fallback to network map.)
+     */
+    fun lookupSigned(hash: SecureHash): SignedDataWithCert<NetworkParameters>?
+
+    /**
+     * Checks if parameters with given hash are in the storage.
+     */
+    fun hasParameters(hash: SecureHash): Boolean
 
-interface NetworkParametersServiceInternal : NetworkParametersService {
     /**
      * Returns the [NotaryInfo] for a notary [party] in the current or any historic network parameter whitelist, or null if not found.
      */
     fun getHistoricNotary(party: Party): NotaryInfo?
+
+    /**
+     * Save signed network parameters data. Internally network parameters bytes should be stored with the signature.
+     * It's because of ability of older nodes to function in network where parameters were extended with new fields.
+     * Hash should always be calculated over the serialized bytes.
+     */
+    fun saveParameters(signedNetworkParameters: SignedDataWithCert<NetworkParameters>)
+
+    /**
+     * Set information that given parameters are current parameters for the network.
+     */
+    fun setCurrentParameters(currentSignedParameters: SignedDataWithCert<NetworkParameters>, trustRoot: X509Certificate)
 }
diff --git a/core/src/main/kotlin/net/corda/core/internal/ResolveTransactionsFlow.kt b/core/src/main/kotlin/net/corda/core/internal/ResolveTransactionsFlow.kt
index 5816266db2..ff8291cd0c 100644
--- a/core/src/main/kotlin/net/corda/core/internal/ResolveTransactionsFlow.kt
+++ b/core/src/main/kotlin/net/corda/core/internal/ResolveTransactionsFlow.kt
@@ -77,6 +77,8 @@ class ResolveTransactionsFlow(txHashesArg: Set<SecureHash>,
     @Suspendable
     @Throws(FetchDataFlow.HashNotFound::class, FetchDataFlow.IllegalTransactionRequest::class)
     override fun call() {
+        val counterpartyPlatformVersion = serviceHub.networkMapCache.getNodeByLegalIdentity(otherSide.counterparty)?.platformVersion ?:
+                throw FlowException("Couldn't retrieve party's ${otherSide.counterparty} platform version from NetworkMapCache")
         val newTxns = ArrayList<SignedTransaction>(txHashes.size)
         // Start fetching data.
         for (pageNumber in 0..(txHashes.size - 1) / RESOLUTION_PAGE_SIZE) {
@@ -85,6 +87,11 @@ class ResolveTransactionsFlow(txHashesArg: Set<SecureHash>,
             newTxns += downloadDependencies(page)
             val txsWithMissingAttachments = if (pageNumber == 0) signedTransaction?.let { newTxns + it } ?: newTxns else newTxns
             fetchMissingAttachments(txsWithMissingAttachments)
+            // Fetch missing parameters flow was added in version 4. This check is needed so we don't end up with node V4 sending parameters
+            // request to node V3 that doesn't know about this protocol.
+            if (counterpartyPlatformVersion >= 4) {
+                fetchMissingParameters(txsWithMissingAttachments)
+            }
         }
         otherSide.send(FetchDataFlow.Request.End)
         // Finish fetching data.
@@ -180,4 +187,13 @@ class ResolveTransactionsFlow(txHashesArg: Set<SecureHash>,
         if (missingAttachments.isNotEmpty())
             subFlow(FetchAttachmentsFlow(missingAttachments.toSet(), otherSide))
     }
+
+    // TODO This can also be done in parallel. See comment to [fetchMissingAttachments] above.
+    @Suspendable
+    private fun fetchMissingParameters(downloads: List<SignedTransaction>) {
+        val parameters = downloads.mapNotNull { it.networkParametersHash }
+        val missingParameters = parameters.filter { !(serviceHub.networkParametersService as NetworkParametersStorage).hasParameters(it) }
+        if (missingParameters.isNotEmpty())
+            subFlow(FetchNetworkParametersFlow(missingParameters.toSet(), otherSide))
+    }
 }
diff --git a/core/src/test/kotlin/net/corda/core/internal/NetworkParametersResolutionTest.kt b/core/src/test/kotlin/net/corda/core/internal/NetworkParametersResolutionTest.kt
new file mode 100644
index 0000000000..5383700d3c
--- /dev/null
+++ b/core/src/test/kotlin/net/corda/core/internal/NetworkParametersResolutionTest.kt
@@ -0,0 +1,132 @@
+package net.corda.core.internal
+
+import net.corda.core.crypto.Crypto
+import net.corda.core.crypto.SignableData
+import net.corda.core.crypto.SignatureMetadata
+import net.corda.core.identity.CordaX500Name
+import net.corda.core.identity.Party
+import net.corda.core.node.NetworkParameters
+import net.corda.core.node.NotaryInfo
+import net.corda.core.node.ServiceHub
+import net.corda.core.serialization.SerializationFactory
+import net.corda.core.serialization.serialize
+import net.corda.core.transactions.SignedTransaction
+import net.corda.core.transactions.TransactionBuilder
+import net.corda.core.transactions.WireTransaction
+import net.corda.core.utilities.getOrThrow
+import net.corda.nodeapi.internal.createDevNetworkMapCa
+import net.corda.nodeapi.internal.crypto.CertificateAndKeyPair
+import net.corda.testing.common.internal.testNetworkParameters
+import net.corda.testing.contracts.DummyContract
+import net.corda.testing.core.singleIdentity
+import net.corda.testing.node.MockNetwork
+import net.corda.testing.node.MockNetworkParameters
+import net.corda.testing.node.StartedMockNode
+import net.corda.testing.node.internal.DUMMY_CONTRACTS_CORDAPP
+import net.corda.testing.node.internal.cordappForClasses
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+
+class NetworkParametersResolutionTest {
+    private lateinit var params2: NetworkParameters
+    private val certKeyPair: CertificateAndKeyPair = createDevNetworkMapCa()
+    private lateinit var mockNet: MockNetwork
+    private lateinit var notaryNode: StartedMockNode
+    private lateinit var megaCorpNode: StartedMockNode
+    private lateinit var miniCorpNode: StartedMockNode
+    private lateinit var megaCorpParty: Party
+    private lateinit var miniCorpParty: Party
+    private lateinit var notaryParty: Party
+
+    @Before
+    fun setup() {
+        mockNet = MockNetwork(MockNetworkParameters(
+                cordappsForAllNodes = listOf(DUMMY_CONTRACTS_CORDAPP,  cordappForClasses(ResolveTransactionsFlowTest.TestFlow::class.java, ResolveTransactionsFlowTest.TestResponseFlow::class.java))))
+        notaryNode = mockNet.defaultNotaryNode
+        megaCorpNode = mockNet.createPartyNode(CordaX500Name("MegaCorp", "London", "GB"))
+        miniCorpNode = mockNet.createPartyNode(CordaX500Name("MiniCorp", "London", "GB"))
+        notaryParty = mockNet.defaultNotaryIdentity
+        megaCorpParty = megaCorpNode.info.singleIdentity()
+        miniCorpParty = miniCorpNode.info.singleIdentity()
+        params2 = testNetworkParameters(epoch = 2, minimumPlatformVersion = 3, notaries = listOf((NotaryInfo(notaryParty, true))))
+    }
+
+    @After
+    fun tearDown() {
+        mockNet.stopNodes()
+    }
+
+    // This function is resolving and signing WireTransaction with special parameters.
+    private fun TransactionBuilder.toSignedTransactionWithParameters(parameters: NetworkParameters?, services: ServiceHub): SignedTransaction {
+        val wtx = toWireTransaction(services)
+        val wtxWithHash = SerializationFactory.defaultFactory.withCurrentContext(null) {
+            WireTransaction(
+                    createComponentGroups(
+                            wtx.inputs,
+                            wtx.outputs,
+                            wtx.commands,
+                            wtx.attachments,
+                            wtx.notary,
+                            wtx.timeWindow,
+                            wtx.references,
+                            parameters?.serialize()?.hash),
+                    wtx.privacySalt
+            )
+        }
+        val publicKey = services.myInfo.singleIdentity().owningKey
+        val signatureMetadata = SignatureMetadata(services.myInfo.platformVersion, Crypto.findSignatureScheme(publicKey).schemeNumberID)
+        val signableData = SignableData(wtxWithHash.id, signatureMetadata)
+        val sig = services.keyManagementService.sign(signableData, publicKey)
+        return SignedTransaction(wtxWithHash, listOf(sig))
+    }
+
+    // Similar to ResolveTransactionsFlowTest but creates transactions with given network parameters
+    // First transaction in pair is dependency of the second one.
+    private fun makeTransactions(parameters1: NetworkParameters?, parameters2: NetworkParameters?): Pair<SignedTransaction, SignedTransaction> {
+        // Make a chain of custody of dummy states and insert into node A.
+        val dummy1: SignedTransaction = DummyContract.generateInitial(0, notaryParty, megaCorpParty.ref(1)).let {
+            val ptx = it.toSignedTransactionWithParameters(parameters1, megaCorpNode.services)
+            notaryNode.services.addSignature(ptx, notaryParty.owningKey)
+        }
+        val dummy2: SignedTransaction = DummyContract.move(dummy1.tx.outRef(0), miniCorpParty).let {
+            val ptx = it.toSignedTransactionWithParameters(parameters2, megaCorpNode.services)
+            notaryNode.services.addSignature(ptx, notaryParty.owningKey)
+        }
+        megaCorpNode.transaction {
+            megaCorpNode.services.recordTransactions(dummy1, dummy2)
+            // Record parameters too.
+            with(megaCorpNode.services.networkParametersService as NetworkParametersStorage) {
+                parameters1?.let { saveParameters(certKeyPair.sign(it)) }
+                parameters2?.let { saveParameters(certKeyPair.sign(it)) }
+            }
+        }
+        return Pair(dummy1, dummy2)
+    }
+
+    @Test
+    fun `request parameters that are not in the storage`() {
+        val params1 = miniCorpNode.services.networkParameters
+        val hash1 = params1.serialize().hash
+        val hash2 = params2.serialize().hash
+        // Create two transactions on megaCorpNode
+        val (stx1, stx2) = makeTransactions(params1, params2)
+        assertThat(stx1.networkParametersHash).isEqualTo(hash1)
+        assertThat(stx2.networkParametersHash).isEqualTo(hash2)
+        miniCorpNode.transaction {
+            assertThat(miniCorpNode.services.networkParametersService.lookup(hash1)).isNotNull()
+            assertThat(miniCorpNode.services.networkParametersService.lookup(hash2)).isNull()
+        }
+        // miniCorpNode resolves the stx2 from megaCorpParty
+        val p = ResolveTransactionsFlowTest.TestFlow(setOf(stx2.id), megaCorpParty)
+        val future = miniCorpNode.startFlow(p)
+        mockNet.runNetwork()
+        future.getOrThrow()
+        miniCorpNode.transaction {
+            // Check that parameters were downloaded to the storage.
+            assertThat(miniCorpNode.services.networkParametersService.lookup(hash1)).isEqualTo(params1)
+            assertThat(miniCorpNode.services.networkParametersService.lookup(hash2)).isEqualTo(params2)
+        }
+    }
+}
\ No newline at end of file
diff --git a/core/src/test/kotlin/net/corda/core/internal/ResolveTransactionsFlowTest.kt b/core/src/test/kotlin/net/corda/core/internal/ResolveTransactionsFlowTest.kt
index da27807e1b..98861f2399 100644
--- a/core/src/test/kotlin/net/corda/core/internal/ResolveTransactionsFlowTest.kt
+++ b/core/src/test/kotlin/net/corda/core/internal/ResolveTransactionsFlowTest.kt
@@ -229,7 +229,7 @@ class ResolveTransactionsFlowTest {
 
 
     @InitiatingFlow
-    private open class TestFlow(val otherSide: Party, private val resolveTransactionsFlowFactory: (FlowSession) -> ResolveTransactionsFlow, private val txCountLimit: Int? = null) : FlowLogic<Unit>() {
+    open class TestFlow(val otherSide: Party, private val resolveTransactionsFlowFactory: (FlowSession) -> ResolveTransactionsFlow, private val txCountLimit: Int? = null) : FlowLogic<Unit>() {
         constructor(txHashes: Set<SecureHash>, otherSide: Party, txCountLimit: Int? = null) : this(otherSide, { ResolveTransactionsFlow(txHashes, it) }, txCountLimit = txCountLimit)
         constructor(stx: SignedTransaction, otherSide: Party) : this(otherSide, { ResolveTransactionsFlow(stx, it) })
 
@@ -243,7 +243,7 @@ class ResolveTransactionsFlowTest {
     }
     @Suppress("unused")
     @InitiatedBy(TestFlow::class)
-    private class TestResponseFlow(val otherSideSession: FlowSession) : FlowLogic<Void?>() {
+    class TestResponseFlow(val otherSideSession: FlowSession) : FlowLogic<Void?>() {
         @Suspendable
         override fun call() = subFlow(TestNoSecurityDataVendingFlow(otherSideSession))
     }
diff --git a/node/src/main/kotlin/net/corda/node/internal/DBNetworkParametersStorage.kt b/node/src/main/kotlin/net/corda/node/internal/DBNetworkParametersStorage.kt
index 2cef9156c4..52abfb3e26 100644
--- a/node/src/main/kotlin/net/corda/node/internal/DBNetworkParametersStorage.kt
+++ b/node/src/main/kotlin/net/corda/node/internal/DBNetworkParametersStorage.kt
@@ -2,10 +2,7 @@ package net.corda.node.internal
 
 import net.corda.core.crypto.SecureHash
 import net.corda.core.identity.Party
-import net.corda.core.internal.DigitalSignatureWithCert
-import net.corda.core.internal.NamedCacheFactory
-import net.corda.core.internal.SignedDataWithCert
-import net.corda.core.internal.NetworkParametersServiceInternal
+import net.corda.core.internal.*
 import net.corda.core.node.NetworkParameters
 import net.corda.core.node.NotaryInfo
 import net.corda.core.serialization.SerializedBytes
@@ -26,23 +23,6 @@ import org.apache.commons.lang.ArrayUtils
 import java.security.cert.X509Certificate
 import javax.persistence.*
 
-interface NetworkParametersStorage : NetworkParametersServiceInternal {
-    /**
-     * Return parameters epoch for the given parameters hash. Null if there are no parameters for this hash in the storage and we are unable to
-     * get them from network map.
-     */
-    fun getEpochFromHash(hash: SecureHash): Int?
-
-    /**
-     * Save signed network parameters data. Internally network parameters bytes should be stored with the signature.
-     * It's because of ability of older nodes to function in network where parameters were extended with new fields.
-     * Hash should always be calculated over the serialized bytes.
-     */
-    fun saveParameters(signedNetworkParameters: SignedDataWithCert<NetworkParameters>)
-
-    fun setCurrentParameters(currentSignedParameters: SignedDataWithCert<NetworkParameters>, trustRoot: X509Certificate)
-}
-
 class DBNetworkParametersStorage(
         cacheFactory: NamedCacheFactory,
         private val database: CordaPersistence,
@@ -94,6 +74,12 @@ class DBNetworkParametersStorage(
 
     override fun getEpochFromHash(hash: SecureHash): Int? = lookup(hash)?.epoch
 
+    override fun lookupSigned(hash: SecureHash): SignedDataWithCert<NetworkParameters>? {
+        return database.transaction { hashToParameters[hash] }
+    }
+
+    override fun hasParameters(hash: SecureHash): Boolean = hash in hashToParameters
+
     override fun saveParameters(signedNetworkParameters: SignedNetworkParameters) {
         log.trace { "Saving new network parameters to network parameters storage." }
         val networkParameters = signedNetworkParameters.verified()
@@ -104,7 +90,6 @@ class DBNetworkParametersStorage(
         }
     }
 
-    // TODO For the future we could get them also as signed (by network operator) attachments on transactions.
     private fun tryDownloadUnknownParameters(parametersHash: SecureHash): NetworkParameters? {
         return if (networkMapClient != null) {
             try {
diff --git a/node/src/main/kotlin/net/corda/node/services/network/NetworkMapUpdater.kt b/node/src/main/kotlin/net/corda/node/services/network/NetworkMapUpdater.kt
index a3e4ca8ab2..bb8cce5116 100644
--- a/node/src/main/kotlin/net/corda/node/services/network/NetworkMapUpdater.kt
+++ b/node/src/main/kotlin/net/corda/node/services/network/NetworkMapUpdater.kt
@@ -13,7 +13,6 @@ import net.corda.core.node.services.KeyManagementService
 import net.corda.core.serialization.serialize
 import net.corda.core.utilities.contextLogger
 import net.corda.core.utilities.minutes
-import net.corda.node.internal.NetworkParametersStorage
 import net.corda.node.services.api.NetworkMapCacheInternal
 import net.corda.node.services.config.NetworkParameterAcceptanceSettings
 import net.corda.node.utilities.NamedThreadFactory
diff --git a/node/src/test/kotlin/net/corda/node/services/network/NetworkMapUpdaterTest.kt b/node/src/test/kotlin/net/corda/node/services/network/NetworkMapUpdaterTest.kt
index 5528fd59b0..e66e22e5b9 100644
--- a/node/src/test/kotlin/net/corda/node/services/network/NetworkMapUpdaterTest.kt
+++ b/node/src/test/kotlin/net/corda/node/services/network/NetworkMapUpdaterTest.kt
@@ -18,7 +18,6 @@ import net.corda.core.node.services.AttachmentId
 import net.corda.core.serialization.serialize
 import net.corda.core.utilities.millis
 import net.corda.node.VersionInfo
-import net.corda.node.internal.NetworkParametersStorage
 import net.corda.node.services.api.NetworkMapCacheInternal
 import net.corda.node.services.config.NetworkParameterAcceptanceSettings
 import net.corda.nodeapi.internal.NodeInfoAndSigned
diff --git a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt
index b6f425aa68..fff4e46a12 100644
--- a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt
+++ b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/InternalMockNetwork.kt
@@ -28,7 +28,6 @@ import net.corda.core.utilities.seconds
 import net.corda.node.VersionInfo
 import net.corda.node.internal.AbstractNode
 import net.corda.node.internal.InitiatedFlowFactory
-import net.corda.node.internal.NetworkParametersStorage
 import net.corda.node.internal.NodeFlowManager
 import net.corda.node.services.api.FlowStarter
 import net.corda.node.services.api.ServiceHubInternal
diff --git a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/MockNetworkParametersService.kt b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/MockNetworkParametersService.kt
index 497c249843..d2ef2f39a4 100644
--- a/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/MockNetworkParametersService.kt
+++ b/testing/node-driver/src/main/kotlin/net/corda/testing/node/internal/MockNetworkParametersService.kt
@@ -2,11 +2,12 @@ package net.corda.testing.node.internal
 
 import net.corda.core.crypto.SecureHash
 import net.corda.core.identity.Party
+import net.corda.core.internal.NetworkParametersStorage
 import net.corda.core.internal.SignedDataWithCert
 import net.corda.core.node.NetworkParameters
 import net.corda.core.node.NotaryInfo
 import net.corda.core.serialization.serialize
-import net.corda.node.internal.NetworkParametersStorage
+import net.corda.nodeapi.internal.network.SignedNetworkParameters
 import net.corda.nodeapi.internal.network.verifiedNetworkMapCert
 import net.corda.testing.common.internal.testNetworkParameters
 import net.corda.testing.internal.withTestSerializationEnvIfNotSet
@@ -15,6 +16,7 @@ import java.time.Instant
 
 class MockNetworkParametersStorage(private var currentParameters: NetworkParameters = testNetworkParameters(modifiedTime = Instant.MIN)) : NetworkParametersStorage {
     private val hashToParametersMap: HashMap<SecureHash, NetworkParameters> = HashMap()
+    private val hashToSignedParametersMap: HashMap<SecureHash, SignedNetworkParameters> = HashMap()
 
     init {
         storeCurrentParameters()
@@ -29,6 +31,12 @@ class MockNetworkParametersStorage(private var currentParameters: NetworkParamet
         setCurrentParametersUnverified(currentSignedParameters.verifiedNetworkMapCert(trustRoot))
     }
 
+    override fun lookupSigned(hash: SecureHash): SignedDataWithCert<NetworkParameters>? {
+        return hashToSignedParametersMap[hash]
+    }
+
+    override fun hasParameters(hash: SecureHash): Boolean = hash in hashToParametersMap
+
     override val currentHash: SecureHash
         get() {
             return withTestSerializationEnvIfNotSet {
@@ -42,6 +50,7 @@ class MockNetworkParametersStorage(private var currentParameters: NetworkParamet
         val networkParameters = signedNetworkParameters.verified()
         val hash = signedNetworkParameters.raw.hash
         hashToParametersMap[hash] = networkParameters
+        hashToSignedParametersMap[hash] = signedNetworkParameters
     }
 
     override fun getHistoricNotary(party: Party): NotaryInfo? {