diff --git a/core/src/main/kotlin/net/corda/protocols/AbstractStateReplacementProtocol.kt b/core/src/main/kotlin/net/corda/protocols/AbstractStateReplacementProtocol.kt
index bbc5a8f0dc..bfaa64851d 100644
--- a/core/src/main/kotlin/net/corda/protocols/AbstractStateReplacementProtocol.kt
+++ b/core/src/main/kotlin/net/corda/protocols/AbstractStateReplacementProtocol.kt
@@ -105,7 +105,7 @@ abstract class AbstractStateReplacementProtocol<T> {
         }
 
         @Suspendable
-        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.LegallyIdentifiable {
+        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.WithKey {
             progressTracker.currentStep = NOTARY
             return subProtocol(NotaryProtocol.Client(stx))
         }
diff --git a/core/src/main/kotlin/net/corda/protocols/NotaryProtocol.kt b/core/src/main/kotlin/net/corda/protocols/NotaryProtocol.kt
index fa7ef94067..28abdfcf61 100644
--- a/core/src/main/kotlin/net/corda/protocols/NotaryProtocol.kt
+++ b/core/src/main/kotlin/net/corda/protocols/NotaryProtocol.kt
@@ -22,7 +22,7 @@ object NotaryProtocol {
      *                         by another transaction or the timestamp is invalid.
      */
     open class Client(private val stx: SignedTransaction,
-                      override val progressTracker: ProgressTracker = Client.tracker()) : ProtocolLogic<DigitalSignature.LegallyIdentifiable>() {
+                      override val progressTracker: ProgressTracker = Client.tracker()) : ProtocolLogic<DigitalSignature.WithKey>() {
 
         companion object {
 
@@ -36,7 +36,7 @@ object NotaryProtocol {
         lateinit var notaryParty: Party
 
         @Suspendable
-        override fun call(): DigitalSignature.LegallyIdentifiable {
+        override fun call(): DigitalSignature.WithKey {
             progressTracker.currentStep = REQUESTING
             val wtx = stx.tx
             notaryParty = wtx.notary ?: throw IllegalStateException("Transaction does not specify a Notary")
@@ -56,7 +56,7 @@ object NotaryProtocol {
         }
 
         @Throws(NotaryException::class, IllegalStateException::class)
-        private fun validateResponse(response: UntrustworthyData<Result>): DigitalSignature.LegallyIdentifiable {
+        private fun validateResponse(response: UntrustworthyData<Result>): DigitalSignature.WithKey {
             return response.unwrap { notaryResult ->
                 progressTracker.currentStep = VALIDATING
                 when (notaryResult) {
@@ -74,8 +74,8 @@ object NotaryProtocol {
             }
         }
 
-        private fun validateSignature(sig: DigitalSignature.LegallyIdentifiable, data: ByteArray) {
-            check(sig.signer == notaryParty) { "Notary result not signed by the correct service" }
+        private fun validateSignature(sig: DigitalSignature.WithKey, data: ByteArray) {
+            check(sig.by in notaryParty.owningKey.keys) { "Invalid signer for the notary result" }
             sig.verifyWithECDSA(data)
         }
     }
@@ -140,11 +140,9 @@ object NotaryProtocol {
             }
         }
 
-        private fun sign(bits: ByteArray): DigitalSignature.LegallyIdentifiable {
-            val myNodeInfo = serviceHub.myInfo
-            val myIdentity = myNodeInfo.notaryIdentity
+        private fun sign(bits: ByteArray): DigitalSignature.WithKey {
             val mySigningKey = serviceHub.notaryIdentityKey
-            return mySigningKey.signWithECDSA(bits, myIdentity)
+            return mySigningKey.signWithECDSA(bits)
         }
     }
 
@@ -153,7 +151,7 @@ object NotaryProtocol {
 
     sealed class Result {
         class Error(val error: NotaryError): Result()
-        class Success(val sig: DigitalSignature.LegallyIdentifiable) : Result()
+        class Success(val sig: DigitalSignature.WithKey) : Result()
     }
 
 }
diff --git a/core/src/main/kotlin/net/corda/protocols/TwoPartyDealProtocol.kt b/core/src/main/kotlin/net/corda/protocols/TwoPartyDealProtocol.kt
index 13d392e9a0..1d001ae098 100644
--- a/core/src/main/kotlin/net/corda/protocols/TwoPartyDealProtocol.kt
+++ b/core/src/main/kotlin/net/corda/protocols/TwoPartyDealProtocol.kt
@@ -41,7 +41,7 @@ object TwoPartyDealProtocol {
     // This object is serialised to the network and is the first protocol message the seller sends to the buyer.
     data class Handshake<out T>(val payload: T, val publicKey: PublicKeyTree)
 
-    class SignaturesFromPrimary(val sellerSig: DigitalSignature.WithKey, val notarySig: DigitalSignature.LegallyIdentifiable)
+    class SignaturesFromPrimary(val sellerSig: DigitalSignature.WithKey, val notarySig: DigitalSignature.WithKey)
 
     /**
      * [Primary] at the end sends the signed tx to all the regulator parties. This a seperate workflow which needs a
@@ -160,7 +160,7 @@ object TwoPartyDealProtocol {
         }
 
         @Suspendable
-        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.LegallyIdentifiable {
+        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.WithKey {
             progressTracker.currentStep = NOTARY
             return subProtocol(NotaryProtocol.Client(stx))
         }
@@ -172,7 +172,7 @@ object TwoPartyDealProtocol {
 
         @Suspendable
         private fun sendSignatures(allPartySignedTx: SignedTransaction, ourSignature: DigitalSignature.WithKey,
-                                   notarySignature: DigitalSignature.LegallyIdentifiable): SignedTransaction {
+                                   notarySignature: DigitalSignature.WithKey): SignedTransaction {
             progressTracker.currentStep = SENDING_SIGS
             val fullySigned = allPartySignedTx + notarySignature
 
diff --git a/finance/src/main/kotlin/net/corda/protocols/TwoPartyTradeProtocol.kt b/finance/src/main/kotlin/net/corda/protocols/TwoPartyTradeProtocol.kt
index 21a42f6e9f..4e2547d742 100644
--- a/finance/src/main/kotlin/net/corda/protocols/TwoPartyTradeProtocol.kt
+++ b/finance/src/main/kotlin/net/corda/protocols/TwoPartyTradeProtocol.kt
@@ -55,7 +55,7 @@ object TwoPartyTradeProtocol {
     )
 
     data class SignaturesFromSeller(val sellerSig: DigitalSignature.WithKey,
-                                    val notarySig: DigitalSignature.LegallyIdentifiable)
+                                    val notarySig: DigitalSignature.WithKey)
 
     open class Seller(val otherParty: Party,
                       val notaryNode: NodeInfo,
@@ -90,7 +90,7 @@ object TwoPartyTradeProtocol {
         }
 
         @Suspendable
-        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.LegallyIdentifiable {
+        private fun getNotarySignature(stx: SignedTransaction): DigitalSignature.WithKey {
             progressTracker.currentStep = NOTARY
             return subProtocol(NotaryProtocol.Client(stx))
         }
@@ -142,7 +142,7 @@ object TwoPartyTradeProtocol {
 
         @Suspendable
         private fun sendSignatures(allPartySignedTx: SignedTransaction, ourSignature: DigitalSignature.WithKey,
-                                   notarySignature: DigitalSignature.LegallyIdentifiable): SignedTransaction {
+                                   notarySignature: DigitalSignature.WithKey): SignedTransaction {
             progressTracker.currentStep = SENDING_SIGS
             val fullySigned = allPartySignedTx + notarySignature
 
diff --git a/node/src/test/kotlin/net/corda/node/services/NotaryServiceTests.kt b/node/src/test/kotlin/net/corda/node/services/NotaryServiceTests.kt
index ebaad2eb0a..f3bb67a55a 100644
--- a/node/src/test/kotlin/net/corda/node/services/NotaryServiceTests.kt
+++ b/node/src/test/kotlin/net/corda/node/services/NotaryServiceTests.kt
@@ -5,8 +5,8 @@ import net.corda.core.contracts.DummyContract
 import net.corda.core.contracts.StateAndRef
 import net.corda.core.contracts.StateRef
 import net.corda.core.contracts.TransactionType
-import net.corda.core.node.services.ServiceInfo
 import net.corda.core.crypto.DigitalSignature
+import net.corda.core.node.services.ServiceInfo
 import net.corda.core.seconds
 import net.corda.core.transactions.SignedTransaction
 import net.corda.core.utilities.DUMMY_NOTARY
@@ -108,7 +108,7 @@ class NotaryServiceTests {
     }
 
 
-    private fun runNotaryClient(stx: SignedTransaction): ListenableFuture<DigitalSignature.LegallyIdentifiable> {
+    private fun runNotaryClient(stx: SignedTransaction): ListenableFuture<DigitalSignature.WithKey> {
         val protocol = NotaryProtocol.Client(stx)
         val future = clientNode.services.startProtocol(protocol)
         net.runNetwork()
diff --git a/node/src/test/kotlin/net/corda/node/services/ValidatingNotaryServiceTests.kt b/node/src/test/kotlin/net/corda/node/services/ValidatingNotaryServiceTests.kt
index 161d8ce8ca..00ff339048 100644
--- a/node/src/test/kotlin/net/corda/node/services/ValidatingNotaryServiceTests.kt
+++ b/node/src/test/kotlin/net/corda/node/services/ValidatingNotaryServiceTests.kt
@@ -78,7 +78,7 @@ class ValidatingNotaryServiceTests {
         assertEquals(setOf(expectedMissingKey), missingKeys)
     }
 
-    private fun runClient(stx: SignedTransaction): ListenableFuture<DigitalSignature.LegallyIdentifiable> {
+    private fun runClient(stx: SignedTransaction): ListenableFuture<DigitalSignature.WithKey> {
         val protocol = NotaryProtocol.Client(stx)
         val future = clientNode.services.startProtocol(protocol)
         net.runNetwork()