Resume Conversations (#86)

* add api client with grpc kotlin * add a deterministic way to get conversations * update crypto logic for deriving keys * get all the tests passing * fix linter issues * write a test for confirmation * confirm android ios and js all make the same keys * remove JS topic test * fix up lint
xmtp · Jul 7, 2023 · 84abe1d · 84abe1d
1 parent 5cba590
commit 84abe1d
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diff --git a/library/src/androidTest/java/org/xmtp/android/library/ConversationTest.kt b/library/src/androidTest/java/org/xmtp/android/library/ConversationTest.kt
@@ -26,7 +26,7 @@ import org.xmtp.android.library.messages.SealedInvitationBuilder
 import org.xmtp.android.library.messages.SealedInvitationHeaderV1
 import org.xmtp.android.library.messages.SignedContentBuilder
 import org.xmtp.android.library.messages.Topic
-import org.xmtp.android.library.messages.createRandom
+import org.xmtp.android.library.messages.createDeterministic
 import org.xmtp.android.library.messages.getPublicKeyBundle
 import org.xmtp.android.library.messages.header
 import org.xmtp.android.library.messages.recoverWalletSignerPublicKey
@@ -330,7 +330,10 @@ class ConversationTest {
             it.conversationId = "https://example.com/1"
         }.build()
         val invitationv1 =
-            InvitationV1.newBuilder().build().createRandom(context = invitationContext)
+            InvitationV1.newBuilder().build().createDeterministic(
+                sender = client.keys,
+                recipient = fakeContactClient.keys.getPublicKeyBundle(), context = invitationContext
+            )
         val senderBundle = client.privateKeyBundleV1?.toV2()
         assertEquals(
             senderBundle?.identityKey?.publicKey?.recoverWalletSignerPublicKey()?.walletAddress,
@@ -428,7 +431,12 @@ class ConversationTest {
         bobConversation.send(text = "hey alice 1")
         bobConversation.send(text = "hey alice 2")
         bobConversation.send(text = "hey alice 3")
-        val messages = aliceClient.conversations.listBatchMessages(listOf(aliceConversation.topic, bobConversation.topic))
+        val messages = aliceClient.conversations.listBatchMessages(
+            listOf(
+                aliceConversation.topic,
+                bobConversation.topic
+            )
+        )
         assertEquals(3, messages.size)
     }
 

diff --git a/library/src/androidTest/java/org/xmtp/android/library/ConversationsTest.kt b/library/src/androidTest/java/org/xmtp/android/library/ConversationsTest.kt
@@ -12,7 +12,7 @@ import org.xmtp.android.library.messages.MessageV1Builder
 import org.xmtp.android.library.messages.PrivateKeyBuilder
 import org.xmtp.android.library.messages.SealedInvitationBuilder
 import org.xmtp.android.library.messages.Topic
-import org.xmtp.android.library.messages.createRandom
+import org.xmtp.android.library.messages.createDeterministic
 import org.xmtp.android.library.messages.getPublicKeyBundle
 import org.xmtp.android.library.messages.toPublicKeyBundle
 import org.xmtp.android.library.messages.walletAddress
@@ -28,8 +28,17 @@ class ConversationsTest {
         val created = Date()
         val newWallet = PrivateKeyBuilder()
         val newClient = Client().create(account = newWallet, apiClient = fixtures.fakeApiClient)
-        val message = MessageV1Builder.buildEncode(sender = newClient.privateKeyBundleV1, recipient = fixtures.aliceClient.v1keys.toPublicKeyBundle(), message = TextCodec().encode(content = "hello").toByteArray(), timestamp = created)
-        val envelope = EnvelopeBuilder.buildFromTopic(topic = Topic.userIntro(client.address), timestamp = created, message = MessageBuilder.buildFromMessageV1(v1 = message).toByteArray())
+        val message = MessageV1Builder.buildEncode(
+            sender = newClient.privateKeyBundleV1,
+            recipient = fixtures.aliceClient.v1keys.toPublicKeyBundle(),
+            message = TextCodec().encode(content = "hello").toByteArray(),
+            timestamp = created
+        )
+        val envelope = EnvelopeBuilder.buildFromTopic(
+            topic = Topic.userIntro(client.address),
+            timestamp = created,
+            message = MessageBuilder.buildFromMessageV1(v1 = message).toByteArray()
+        )
         val conversation = client.conversations.fromIntro(envelope = envelope)
         assertEquals(conversation.peerAddress, newWallet.address)
         assertEquals(conversation.createdAt.time, created.time)
@@ -42,10 +51,22 @@ class ConversationsTest {
         val created = Date()
         val newWallet = PrivateKeyBuilder()
         val newClient = Client().create(account = newWallet, apiClient = fixtures.fakeApiClient)
-        val invitation = InvitationV1.newBuilder().build().createRandom(context = null)
-        val sealed = SealedInvitationBuilder.buildFromV1(sender = newClient.keys, recipient = client.keys.getPublicKeyBundle(), created = created, invitation = invitation)
+        val invitation = InvitationV1.newBuilder().build().createDeterministic(
+            sender = newClient.keys,
+            recipient = client.keys.getPublicKeyBundle()
+        )
+        val sealed = SealedInvitationBuilder.buildFromV1(
+            sender = newClient.keys,
+            recipient = client.keys.getPublicKeyBundle(),
+            created = created,
+            invitation = invitation
+        )
         val peerAddress = fixtures.alice.walletAddress
-        val envelope = EnvelopeBuilder.buildFromTopic(topic = Topic.userInvite(peerAddress), timestamp = created, message = sealed.toByteArray())
+        val envelope = EnvelopeBuilder.buildFromTopic(
+            topic = Topic.userInvite(peerAddress),
+            timestamp = created,
+            message = sealed.toByteArray()
+        )
         val conversation = client.conversations.fromInvite(envelope = envelope)
         assertEquals(conversation.peerAddress, newWallet.address)
         assertEquals(conversation.createdAt.time, created.time)

diff --git a/library/src/androidTest/java/org/xmtp/android/library/InvitationTest.kt b/library/src/androidTest/java/org/xmtp/android/library/InvitationTest.kt
@@ -4,15 +4,17 @@ import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.google.protobuf.kotlin.toByteString
 import org.junit.Assert
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotEquals
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.xmtp.android.library.messages.InvitationV1
+import org.xmtp.android.library.messages.InvitationV1ContextBuilder
 import org.xmtp.android.library.messages.PrivateKey
 import org.xmtp.android.library.messages.PrivateKeyBuilder
 import org.xmtp.android.library.messages.PrivateKeyBundleV1
 import org.xmtp.android.library.messages.SealedInvitation
 import org.xmtp.android.library.messages.SealedInvitationBuilder
-import org.xmtp.android.library.messages.createRandom
+import org.xmtp.android.library.messages.createDeterministic
 import org.xmtp.android.library.messages.generate
 import org.xmtp.android.library.messages.getInvitation
 import org.xmtp.android.library.messages.getPublicKeyBundle
@@ -51,13 +53,17 @@ class InvitationTest {
         val message = conversations[0].messages().firstOrNull()
         Assert.assertEquals(message?.body, "hello")
     }
+
     @Test
     fun testGenerateSealedInvitation() {
         val aliceWallet = FakeWallet.generate()
         val bobWallet = FakeWallet.generate()
         val alice = PrivateKeyBundleV1.newBuilder().build().generate(wallet = aliceWallet)
         val bob = PrivateKeyBundleV1.newBuilder().build().generate(wallet = bobWallet)
-        val invitation = InvitationV1.newBuilder().build().createRandom()
+        val invitation = InvitationV1.newBuilder().build().createDeterministic(
+            sender = alice.toV2(),
+            recipient = bob.toV2().getPublicKeyBundle()
+        )
         val newInvitation = SealedInvitationBuilder.buildFromV1(
             sender = alice.toV2(),
             recipient = bob.toV2().getPublicKeyBundle(),
@@ -86,4 +92,28 @@ class InvitationTest {
             invitation.aes256GcmHkdfSha256.keyMaterial
         )
     }
+
+    @Test
+    fun testDeterministicInvite() {
+        val aliceWallet = FakeWallet.generate()
+        val bobWallet = FakeWallet.generate()
+        val alice = PrivateKeyBundleV1.newBuilder().build().generate(wallet = aliceWallet)
+        val bob = PrivateKeyBundleV1.newBuilder().build().generate(wallet = bobWallet)
+        val makeInvite = { conversationId: String ->
+            InvitationV1.newBuilder().build().createDeterministic(
+                sender = alice.toV2(),
+                recipient = bob.toV2().getPublicKeyBundle(),
+                context = InvitationV1ContextBuilder.buildFromConversation(conversationId)
+            )
+        }
+        // Repeatedly making the same invite should use the same topic/keys
+        val original = makeInvite("example.com/conversation-foo")
+        for (i in 1..10) {
+            val invite = makeInvite("example.com/conversation-foo")
+            assertEquals(original.topic, invite.topic)
+        }
+        // But when the conversationId changes then it use a new topic/keys
+        val invite = makeInvite("example.com/conversation-bar")
+        assertNotEquals(original.topic, invite.topic)
+    }
 }
diff --git a/library/src/androidTest/java/org/xmtp/android/library/MessageTest.kt b/library/src/androidTest/java/org/xmtp/android/library/MessageTest.kt
@@ -21,7 +21,7 @@ import org.xmtp.android.library.messages.PrivateKeyBundleV1
 import org.xmtp.android.library.messages.PublicKeyBundle
 import org.xmtp.android.library.messages.SealedInvitationBuilder
 import org.xmtp.android.library.messages.SignedPublicKeyBundleBuilder
-import org.xmtp.android.library.messages.createRandom
+import org.xmtp.android.library.messages.createDeterministic
 import org.xmtp.android.library.messages.decrypt
 import org.xmtp.android.library.messages.generate
 import org.xmtp.android.library.messages.getPublicKeyBundle
@@ -74,7 +74,11 @@ class MessageTest {
             conversationId = "https://example.com/1"
         }.build()
         val invitationv1 =
-            InvitationV1.newBuilder().build().createRandom(context = invitationContext)
+            InvitationV1.newBuilder().build().createDeterministic(
+                sender = alice.toV2(),
+                recipient = bob.toV2().getPublicKeyBundle(),
+                context = invitationContext
+            )
         val sealedInvitation = SealedInvitationBuilder.buildFromV1(
             sender = alice.toV2(),
             recipient = bob.toV2().getPublicKeyBundle(),

diff --git a/library/src/main/java/org/xmtp/android/library/Conversations.kt b/library/src/main/java/org/xmtp/android/library/Conversations.kt
@@ -14,7 +14,7 @@ import org.xmtp.android.library.messages.SealedInvitation
 import org.xmtp.android.library.messages.SealedInvitationBuilder
 import org.xmtp.android.library.messages.SignedPublicKeyBundle
 import org.xmtp.android.library.messages.Topic
-import org.xmtp.android.library.messages.createRandom
+import org.xmtp.android.library.messages.createDeterministic
 import org.xmtp.android.library.messages.decrypt
 import org.xmtp.android.library.messages.getInvitation
 import org.xmtp.android.library.messages.header
@@ -27,7 +27,6 @@ import org.xmtp.android.library.messages.walletAddress
 import org.xmtp.proto.keystore.api.v1.Keystore.TopicMap.TopicData
 import org.xmtp.proto.message.contents.Contact
 import org.xmtp.proto.message.contents.Invitation
-import java.lang.Exception
 import java.util.Date
 
 data class Conversations(
@@ -132,7 +131,8 @@ data class Conversations(
         }
         // We don't have an existing conversation, make a v2 one
         val recipient = contact.toSignedPublicKeyBundle()
-        val invitation = Invitation.InvitationV1.newBuilder().build().createRandom(context)
+        val invitation = Invitation.InvitationV1.newBuilder().build()
+            .createDeterministic(client.keys, recipient, context)
         val sealedInvitation =
             sendInvitation(recipient = recipient, invitation = invitation, created = Date())
         val conversationV2 = ConversationV2.create(

diff --git a/library/src/main/java/org/xmtp/android/library/Crypto.kt b/library/src/main/java/org/xmtp/android/library/Crypto.kt
@@ -3,10 +3,14 @@ package org.xmtp.android.library
 import android.util.Log
 import com.google.crypto.tink.subtle.Hkdf
 import com.google.protobuf.kotlin.toByteString
+import org.bouncycastle.crypto.digests.SHA256Digest
+import org.bouncycastle.crypto.generators.HKDFBytesGenerator
+import org.bouncycastle.crypto.params.HKDFParameters
 import org.xmtp.proto.message.contents.CiphertextOuterClass
 import java.security.GeneralSecurityException
 import java.security.SecureRandom
 import javax.crypto.Cipher
+import javax.crypto.Mac
 import javax.crypto.spec.GCMParameterSpec
 import javax.crypto.spec.SecretKeySpec
 
@@ -74,4 +78,25 @@ class Crypto {
             }
         }
     }
+
+    fun calculateMac(secret: ByteArray, message: ByteArray): ByteArray {
+        val sha256HMAC: Mac = Mac.getInstance("HmacSHA256")
+        val secretKey = SecretKeySpec(secret, "HmacSHA256")
+        sha256HMAC.init(secretKey)
+        return sha256HMAC.doFinal(message)
+    }
+
+    fun deriveKey(
+        secret: ByteArray,
+        salt: ByteArray,
+        info: ByteArray,
+    ): ByteArray {
+        val derivationParameters = HKDFParameters(secret, salt, info)
+        val digest = SHA256Digest()
+        val hkdfGenerator = HKDFBytesGenerator(digest)
+        hkdfGenerator.init(derivationParameters)
+        val hkdf = ByteArray(32)
+        hkdfGenerator.generateBytes(hkdf, 0, hkdf.size)
+        return hkdf
+    }
 }
diff --git a/library/src/main/java/org/xmtp/android/library/messages/InvitationV1.kt b/library/src/main/java/org/xmtp/android/library/messages/InvitationV1.kt
@@ -2,6 +2,8 @@ package org.xmtp.android.library.messages
 
 import com.google.crypto.tink.subtle.Base64.encodeToString
 import com.google.protobuf.kotlin.toByteString
+import org.xmtp.android.library.Crypto
+import org.xmtp.android.library.toHex
 import org.xmtp.proto.message.contents.Invitation
 import org.xmtp.proto.message.contents.Invitation.InvitationV1.Context
 import java.security.SecureRandom
@@ -12,8 +14,8 @@ class InvitationV1Builder {
     companion object {
         fun buildFromTopic(
             topic: Topic,
-            context: Invitation.InvitationV1.Context? = null,
-            aes256GcmHkdfSha256: Invitation.InvitationV1.Aes256gcmHkdfsha256
+            context: Context? = null,
+            aes256GcmHkdfSha256: Invitation.InvitationV1.Aes256gcmHkdfsha256,
         ): InvitationV1 {
             return InvitationV1.newBuilder().apply {
                 this.topic = topic.description
@@ -26,18 +28,18 @@ class InvitationV1Builder {
 
         fun buildContextFromId(
             conversationId: String = "",
-            metadata: Map<String, String> = mapOf()
-        ): Invitation.InvitationV1.Context {
-            return Invitation.InvitationV1.Context.newBuilder().apply {
+            metadata: Map<String, String> = mapOf(),
+        ): Context {
+            return Context.newBuilder().apply {
                 this.conversationId = conversationId
                 this.putAllMetadata(metadata)
             }.build()
         }
     }
 }
 
-fun InvitationV1.createRandom(context: Invitation.InvitationV1.Context? = null): InvitationV1 {
-    val inviteContext = context ?: Invitation.InvitationV1.Context.newBuilder().build()
+fun InvitationV1.createRandom(context: Context? = null): InvitationV1 {
+    val inviteContext = context ?: Context.newBuilder().build()
     val randomBytes = SecureRandom().generateSeed(32)
     val randomString = encodeToString(randomBytes, 0).replace(Regex("=*$"), "")
         .replace(Regex("[^A-Za-z0-9]"), "")
@@ -54,11 +56,50 @@ fun InvitationV1.createRandom(context: Invitation.InvitationV1.Context? = null):
     )
 }
 
+fun InvitationV1.createDeterministic(
+    sender: PrivateKeyBundleV2,
+    recipient: SignedPublicKeyBundle,
+    context: Context? = null,
+): InvitationV1 {
+    val inviteContext = context ?: Context.newBuilder().build()
+    val secret = sender.sharedSecret(
+        peer = recipient,
+        myPreKey = sender.preKeysList[0].publicKey,
+        isRecipient = false
+    )
+
+    val addresses = arrayOf(sender.toV1().walletAddress, recipient.walletAddress)
+    addresses.sort()
+
+    val msg = if (context != null && !context.conversationId.isNullOrBlank()) {
+        context.conversationId + addresses.joinToString(separator = ",")
+    } else {
+        addresses.joinToString(separator = ",")
+    }
+
+    val topicId = Crypto().calculateMac(secret = secret, message = msg.toByteArray()).toHex()
+    val topic = Topic.directMessageV2(topicId)
+    val keyMaterial = Crypto().deriveKey(
+        secret = secret,
+        salt = "__XMTP__INVITATION__SALT__XMTP__".toByteArray(),
+        info = listOf("0").plus(addresses).joinToString(separator = "|").toByteArray()
+    )
+    val aes256GcmHkdfSha256 = Invitation.InvitationV1.Aes256gcmHkdfsha256.newBuilder().apply {
+        this.keyMaterial = keyMaterial.toByteString()
+    }.build()
+
+    return InvitationV1Builder.buildFromTopic(
+        topic = topic,
+        context = inviteContext,
+        aes256GcmHkdfSha256 = aes256GcmHkdfSha256
+    )
+}
+
 class InvitationV1ContextBuilder {
     companion object {
         fun buildFromConversation(
             conversationId: String = "",
-            metadata: Map<String, String> = mapOf()
+            metadata: Map<String, String> = mapOf(),
         ): Context {
             return Context.newBuilder().also {
                 it.conversationId = conversationId