Receiving and decoding private Zaps

Private zaps get decoded correctly. TODO: Update events or at least notifications in Damus to replace anon sender with the one from decrypted message. Bonus: Show Content of the Zap Message
2025-09-25 20:47:49 +02:00 · 2023-04-17 20:10:36 +02:00
parent ff490a2b14
commit 5e6e2835ca
6 changed files with 51 additions and 32 deletions
--- a/app/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/model/LocalCache.kt
@@ -7,6 +7,7 @@ import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.vitorpamplona.amethyst.service.model.*
 import com.vitorpamplona.amethyst.service.relays.Relay
 import com.vitorpamplona.amethyst.ui.components.BundledUpdate
+import com.vitorpamplona.amethyst.ui.dal.NotificationFeedFilter
 import fr.acinq.secp256k1.Hex
 import kotlinx.coroutines.*
 import nostr.postr.toNpub
@@ -622,6 +623,27 @@ object LocalCache {
        }
    }

+    fun checkPrivateZap(zaprequest: Event): Event {
+        var anonTag = zaprequest.tags.firstOrNull { t -> t.count() >= 2 && t[0] == "anon" }
+        if (anonTag != null && anonTag.size > 1) {
+            var encnote = anonTag?.elementAt(1)
+            if (encnote != null && encnote != "") {
+                try {
+                    val loggedInUserHex = NotificationFeedFilter.account.loggedIn.privKey!! // Replace without Filter
+                    var note = LnZapRequestEvent.decrypt_privatezap_message(encnote, loggedInUserHex, zaprequest.pubKey.toByteArray())
+                    var decryptedEvent = Event.fromJson(note)
+                    if (decryptedEvent.kind == 9733) {
+                        zaprequest.pubKey = decryptedEvent.pubKey
+                        zaprequest.content = decryptedEvent.content
+                        // return decryptedEvent
+                    }
+                } catch (e: Exception) {
+                    e.printStackTrace()
+                }
+            }
+        }
+        return zaprequest
+    }
    fun consume(event: LnZapRequestEvent) {
        val note = getOrCreateNote(event.id)

--- a/app/src/main/java/com/vitorpamplona/amethyst/service/model/Event.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/model/Event.kt
@@ -15,11 +15,11 @@ import java.util.*

 open class Event(
    val id: HexKey,
-    @SerializedName("pubkey") val pubKey: HexKey,
+    @SerializedName("pubkey") var pubKey: HexKey,
    @SerializedName("created_at") val createdAt: Long,
    val kind: Int,
    val tags: List<List<String>>,
-    val content: String,
+    var content: String,
    val sig: HexKey
 ) : EventInterface {
    override fun id(): HexKey = id
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapEvent.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapEvent.kt
@@ -42,10 +42,9 @@ class LnZapEvent(
            null
        }
    }
-    override fun message(): String {
-        return message
+    override fun content(): String {
+        return content
    }
-    val message = content

    override fun containedPost(): Event? = try {
        description()?.ifBlank { null }?.let {
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapEventInterface.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapEventInterface.kt
@@ -18,5 +18,4 @@ interface LnZapEventInterface : EventInterface {

    fun containedPost(): Event?

-    fun message(): String
 }
--- a/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapRequestEvent.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapRequestEvent.kt
@@ -6,6 +6,7 @@ import nostr.postr.Utils
 import java.nio.charset.Charset
 import java.security.SecureRandom
 import java.util.*
+import javax.crypto.BadPaddingException
 import javax.crypto.Cipher
 import javax.crypto.spec.IvParameterSpec
 import javax.crypto.spec.SecretKeySpec
@@ -52,21 +53,21 @@ class LnZapRequestEvent(
                privkey = Utils.privkeyCreate()
                pubKey = Utils.pubkeyCreate(privkey).toHexKey()
            } else if (zapType == LnZapEvent.ZapType.PRIVATE) {
-                var enc_prkey = create_private_key(privateKey, originalNote.id(), createdAt)
+                var encryptionprkey = create_private_key(privateKey.toHexKey(), originalNote.id(), createdAt)
                var noteJson = (create(privkey, 9733, listOf(tags[0], tags[1]), message)).toJson()
-                var privreq = encrypt_privatezap_message(noteJson, enc_prkey, originalNote.pubKey().toByteArray())
+                var privreq = encrypt_privatezap_message(noteJson, encryptionprkey, originalNote.pubKey().toByteArray())
                tags = tags + listOf(listOf("anon", privreq))
                content = ""
-                privkey = enc_prkey
-                pubKey = Utils.pubkeyCreate(enc_prkey).toHexKey()
+                privkey = encryptionprkey
+                pubKey = Utils.pubkeyCreate(encryptionprkey).toHexKey()
            }
            val id = generateId(pubKey, createdAt, kind, tags, content)
            val sig = Utils.sign(id, privkey)
            return LnZapRequestEvent(id.toHexKey(), pubKey, createdAt, tags, content, sig.toHexKey())
        }

-        fun create_private_key(privkey: ByteArray, id: String, createdAt: Long): ByteArray {
-            var str = privkey.toHexKey() + id + createdAt.toString()
+        fun create_private_key(privkey: String, id: String, createdAt: Long): ByteArray {
+            var str = privkey + id + createdAt.toString()
            var strbyte = str.toByteArray(Charset.forName("utf-8"))
            return sha256.digest(strbyte)
        }
@@ -79,10 +80,10 @@ class LnZapRequestEvent(
            val keySpec = SecretKeySpec(sharedSecret, "AES")
            val ivSpec = IvParameterSpec(iv)

-            var utf8_message = msg.toByteArray(Charset.forName("utf-8"))
+            var utf8message = msg.toByteArray(Charset.forName("utf-8"))
            val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec)
-            val encryptedMsg = cipher.doFinal(utf8_message)
+            val encryptedMsg = cipher.doFinal(utf8message)

            val encryptedMsgBech32 = Bech32.encode("pzap", Bech32.eight2five(encryptedMsg), Bech32.Encoding.Bech32)
            val ivBech32 = Bech32.encode("iv", Bech32.eight2five(iv), Bech32.Encoding.Bech32)
@@ -92,24 +93,26 @@ class LnZapRequestEvent(

        fun decrypt_privatezap_message(msg: String, privkey: ByteArray, pubkey: ByteArray): String {
            var sharedSecret = Utils.getSharedSecret(privkey, pubkey)
+            if (sharedSecret.size != 16 && sharedSecret.size != 32) {
+                throw IllegalArgumentException("Invalid shared secret size")
+            }
            val parts = msg.split("_")
+            if (parts.size != 2) {
+                throw IllegalArgumentException("Invalid message format")
+            }
            val iv = parts[1].run { Bech32.decode(this) }
            val encryptedMsg = parts.first().run { Bech32.decode(this) }
            val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
            cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(sharedSecret, "AES"), IvParameterSpec(Bech32.five2eight(iv.second, 0)))
-            return String(cipher.doFinal(Bech32.five2eight(encryptedMsg.second, 0)))
-        }

-        fun test_decrypt(privateKey: ByteArray, event: Event): String {
-            val anonTag = event.tags.firstOrNull { t -> t.count() >= 2 && t[0] == "anon" }
-            var encnote = anonTag?.elementAt(1)
-            if (encnote != null) {
-                var enc_prkey2 = create_private_key(privateKey, event.id(), event.createdAt)
-                return decrypt_privatezap_message(encnote, enc_prkey2, event.pubKey().toByteArray())
-            } else {
-                return ""
+            try {
+                val decryptedMsgBytes = cipher.doFinal(Bech32.five2eight(encryptedMsg.second, 0))
+                return String(decryptedMsgBytes)
+            } catch (ex: BadPaddingException) {
+                throw IllegalArgumentException("Bad padding")
            }
        }
+
        fun create(
            userHex: String,
            relays: Set<String>,
@@ -130,7 +133,7 @@ class LnZapRequestEvent(
                pubKey = Utils.pubkeyCreate(privkey).toHexKey()
                tags = tags + listOf(listOf("anon", ""))
            } else if (zapType == LnZapEvent.ZapType.PRIVATE) {
-                var enc_prkey = create_private_key(privateKey, userHex, createdAt)
+                var enc_prkey = create_private_key(privateKey.toHexKey(), userHex, createdAt)
                var noteJson = (create(privkey, 9733, listOf(tags[0], tags[1]), message)).toJson()
                var privreq = encrypt_privatezap_message(noteJson, enc_prkey, userHex.toByteArray())
                tags = tags + listOf(listOf("anon", privreq))
--- a/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/CardFeedViewModel.kt
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/CardFeedViewModel.kt
@@ -8,13 +8,7 @@ import com.vitorpamplona.amethyst.model.LocalCache
 import com.vitorpamplona.amethyst.model.LocalCacheState
 import com.vitorpamplona.amethyst.model.Note
 import com.vitorpamplona.amethyst.model.User
-import com.vitorpamplona.amethyst.service.model.BadgeAwardEvent
-import com.vitorpamplona.amethyst.service.model.ChannelCreateEvent
-import com.vitorpamplona.amethyst.service.model.ChannelMetadataEvent
-import com.vitorpamplona.amethyst.service.model.LnZapEvent
-import com.vitorpamplona.amethyst.service.model.PrivateDmEvent
-import com.vitorpamplona.amethyst.service.model.ReactionEvent
-import com.vitorpamplona.amethyst.service.model.RepostEvent
+import com.vitorpamplona.amethyst.service.model.*
 import com.vitorpamplona.amethyst.ui.components.BundledUpdate
 import com.vitorpamplona.amethyst.ui.dal.FeedFilter
 import com.vitorpamplona.amethyst.ui.dal.NotificationFeedFilter
@@ -88,6 +82,8 @@ open class CardFeedViewModel(val dataSource: FeedFilter<Note>) : ViewModel() {
                if (zappedPost != null) {
                    val zapRequest = zappedPost.zaps.filter { it.value == zapEvent }.keys.firstOrNull()
                    if (zapRequest != null) {
+                        // var newZapRequestEvent = LocalCache.checkPrivateZap(zapRequest.event as Event)
+                        // zapRequest.event = newZapRequestEvent
                        zapsPerEvent.getOrPut(zappedPost, { mutableMapOf() }).put(zapRequest, zapEvent)
                    }
                } else {