Small refactoring to create the PrivateZap Event

quartz/src/main/java/com/vitorpamplona/quartz/events/EventFactory.kt

@@ -41,9 +41,6 @@ class EventFactory {
             ContactListEvent.kind -> ContactListEvent(id, pubKey, createdAt, tags, content, sig)
             DeletionEvent.kind -> DeletionEvent(id, pubKey, createdAt, tags, content, sig)
 
-            // Will never happen.
-            // DirectMessageEvent.kind -> DirectMessageEvent(createdAt, tags, content)
-
             EmojiPackEvent.kind -> EmojiPackEvent(id, pubKey, createdAt, tags, content, sig)
             EmojiPackSelectionEvent.kind -> EmojiPackSelectionEvent(id, pubKey, createdAt, tags, content, sig)
             SealedGossipEvent.kind -> SealedGossipEvent(id, pubKey, createdAt, tags, content, sig)
@@ -59,6 +56,7 @@ class EventFactory {
             LnZapEvent.kind -> LnZapEvent(id, pubKey, createdAt, tags, content, sig)
             LnZapPaymentRequestEvent.kind -> LnZapPaymentRequestEvent(id, pubKey, createdAt, tags, content, sig)
             LnZapPaymentResponseEvent.kind -> LnZapPaymentResponseEvent(id, pubKey, createdAt, tags, content, sig)
+            LnZapPrivateEvent.kind -> LnZapPrivateEvent(id, pubKey, createdAt, tags, content, sig)
             LnZapRequestEvent.kind -> LnZapRequestEvent(id, pubKey, createdAt, tags, content, sig)
             LongTextNoteEvent.kind -> LongTextNoteEvent(id, pubKey, createdAt, tags, content, sig)
             MetadataEvent.kind -> MetadataEvent(id, pubKey, createdAt, tags, content, sig)

quartz/src/main/java/com/vitorpamplona/quartz/events/LnZapPrivateEvent.kt

@@ -0,0 +1,43 @@
+package com.vitorpamplona.quartz.events
+
+import android.util.Log
+import androidx.compose.runtime.Immutable
+import com.vitorpamplona.quartz.crypto.CryptoUtils
+import com.vitorpamplona.quartz.encoders.Bech32
+import com.vitorpamplona.quartz.encoders.HexKey
+import com.vitorpamplona.quartz.encoders.LnInvoiceUtil
+import com.vitorpamplona.quartz.encoders.toHexKey
+import com.vitorpamplona.quartz.utils.TimeUtils
+import java.nio.charset.Charset
+import java.security.SecureRandom
+import javax.crypto.BadPaddingException
+import javax.crypto.Cipher
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
+
+@Immutable
+class LnZapPrivateEvent(
+    id: HexKey,
+    pubKey: HexKey,
+    createdAt: Long,
+    tags: List<List<String>>,
+    content: String,
+    sig: HexKey
+) : Event(id, pubKey, createdAt, kind, tags, content, sig) {
+
+    companion object {
+        const val kind = 9733
+
+        fun create(
+            privateKey: ByteArray,
+            tags: List<List<String>> = emptyList(),
+            content: String = "",
+            createdAt: Long = TimeUtils.now()
+        ): Event {
+            val pubKey = CryptoUtils.pubkeyCreate(privateKey).toHexKey()
+            val id = generateId(pubKey, createdAt, kind, tags, content)
+            val sig = CryptoUtils.sign(id, privateKey).toHexKey()
+            return Event(id.toHexKey(), pubKey, createdAt, kind, tags, content, sig)
+        }
+    }
+}

quartz/src/main/java/com/vitorpamplona/quartz/events/LnZapRequestEvent.kt

@@ -86,9 +86,9 @@ class LnZapRequestEvent(
                 privkey = CryptoUtils.privkeyCreate()
                 pubKey = CryptoUtils.pubkeyCreate(privkey).toHexKey()
             } else if (zapType == LnZapEvent.ZapType.PRIVATE) {
-                var encryptionPrivateKey = createEncryptionPrivateKey(privateKey.toHexKey(), originalNote.id(), createdAt)
+                val encryptionPrivateKey = createEncryptionPrivateKey(privateKey.toHexKey(), originalNote.id(), createdAt)
-                var noteJson = (create(privkey, 9733, listOf(tags[0], tags[1]), message)).toJson()
+                val noteJson = (LnZapPrivateEvent.create(privkey, listOf(tags[0], tags[1]), message)).toJson()
-                var encryptedContent = encryptPrivateZapMessage(noteJson, encryptionPrivateKey, originalNote.pubKey().hexToByteArray())
+                val encryptedContent = encryptPrivateZapMessage(noteJson, encryptionPrivateKey, originalNote.pubKey().hexToByteArray())
                 tags = tags + listOf(listOf("anon", encryptedContent))
                 content = "" // make sure public content is empty, as the content is encrypted
                 privkey = encryptionPrivateKey // sign event with generated privkey
@@ -119,9 +119,9 @@ class LnZapRequestEvent(
                 pubKey = CryptoUtils.pubkeyCreate(privkey).toHexKey()
                 tags = tags + listOf(listOf("anon", ""))
             } else if (zapType == LnZapEvent.ZapType.PRIVATE) {
-                var encryptionPrivateKey = createEncryptionPrivateKey(privateKey.toHexKey(), userHex, createdAt)
+                val encryptionPrivateKey = createEncryptionPrivateKey(privateKey.toHexKey(), userHex, createdAt)
-                var noteJson = (create(privkey, 9733, listOf(tags[0], tags[1]), message)).toJson()
+                val noteJson = LnZapPrivateEvent.create(privkey, listOf(tags[0], tags[1]), message).toJson()
-                var encryptedContent = encryptPrivateZapMessage(noteJson, encryptionPrivateKey, userHex.hexToByteArray())
+                val encryptedContent = encryptPrivateZapMessage(noteJson, encryptionPrivateKey, userHex.hexToByteArray())
                 tags = tags + listOf(listOf("anon", encryptedContent))
                 content = ""
                 privkey = encryptionPrivateKey
@@ -132,21 +132,22 @@ class LnZapRequestEvent(
             return LnZapRequestEvent(id.toHexKey(), pubKey, createdAt, tags, content, sig.toHexKey())
         }
 
+
         fun createEncryptionPrivateKey(privkey: String, id: String, createdAt: Long): ByteArray {
-            var str = privkey + id + createdAt.toString()
+            val str = privkey + id + createdAt.toString()
-            var strbyte = str.toByteArray(Charset.forName("utf-8"))
+            val strbyte = str.toByteArray(Charset.forName("utf-8"))
             return CryptoUtils.sha256(strbyte)
         }
 
         private fun encryptPrivateZapMessage(msg: String, privkey: ByteArray, pubkey: ByteArray): String {
-            var sharedSecret = CryptoUtils.getSharedSecretNIP04(privkey, pubkey)
+            val sharedSecret = CryptoUtils.getSharedSecretNIP04(privkey, pubkey)
             val iv = ByteArray(16)
             SecureRandom().nextBytes(iv)
 
             val keySpec = SecretKeySpec(sharedSecret, "AES")
             val ivSpec = IvParameterSpec(iv)
 
-            var utf8message = msg.toByteArray(Charset.forName("utf-8"))
+            val 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(utf8message)
@@ -158,7 +159,7 @@ class LnZapRequestEvent(
         }
 
         private fun decryptPrivateZapMessage(msg: String, privkey: ByteArray, pubkey: ByteArray): String {
-            var sharedSecret = CryptoUtils.getSharedSecretNIP04(privkey, pubkey)
+            val sharedSecret = CryptoUtils.getSharedSecretNIP04(privkey, pubkey)
             if (sharedSecret.size != 16 && sharedSecret.size != 32) {
                 throw IllegalArgumentException("Invalid shared secret size")
             }
@@ -170,8 +171,10 @@ class LnZapRequestEvent(
             val encryptedMsg = parts.first().run { Bech32.decode(this).second }
             val encryptedBytes = Bech32.five2eight(encryptedMsg, 0)
             val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
-            cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(sharedSecret, "AES"), IvParameterSpec(
+            cipher.init(
-                Bech32.five2eight(iv, 0)))
+                Cipher.DECRYPT_MODE, SecretKeySpec(sharedSecret, "AES"), IvParameterSpec(
+                    Bech32.five2eight(iv, 0))
+            )
 
             try {
                 val decryptedMsgBytes = cipher.doFinal(encryptedBytes)