Send Private Zaps

app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapEvent.kt

@@ -72,7 +72,7 @@ class LnZapEvent(
 
     enum class ZapType() {
         PUBLIC,
-        PRIVATE, // not yet implemented
+        PRIVATE,
         ANONYMOUS,
         NONZAP
     }

app/src/main/java/com/vitorpamplona/amethyst/service/model/LnZapRequestEvent.kt

@@ -1,9 +1,14 @@
 package com.vitorpamplona.amethyst.service.model
 
-import com.vitorpamplona.amethyst.model.HexKey
+import com.vitorpamplona.amethyst.model.*
-import com.vitorpamplona.amethyst.model.toHexKey
+import nostr.postr.Bech32
 import nostr.postr.Utils
-import java.util.Date
+import java.nio.charset.Charset
+import java.security.SecureRandom
+import java.util.*
+import javax.crypto.Cipher
+import javax.crypto.spec.IvParameterSpec
+import javax.crypto.spec.SecretKeySpec
 
 class LnZapRequestEvent(
     id: HexKey,
@@ -28,7 +33,7 @@ class LnZapRequestEvent(
             zapType: LnZapEvent.ZapType,
             createdAt: Long = Date().time / 1000
         ): LnZapRequestEvent {
-            val content = message
+            var content = message
             var privkey = privateKey
             var pubKey = Utils.pubkeyCreate(privateKey).toHexKey()
             var tags = listOf(
@@ -46,12 +51,65 @@ class LnZapRequestEvent(
                 tags = tags + listOf(listOf("anon", ""))
                 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 noteJson = (create(privkey, 9733, listOf(tags[0], tags[1]), message)).toJson()
+                var privreq = encrypt_privatezap_message(noteJson, enc_prkey, originalNote.pubKey().toByteArray())
+                tags = tags + listOf(listOf("anon", privreq))
+                content = ""
+                privkey = enc_prkey
+                pubKey = Utils.pubkeyCreate(enc_prkey).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()
+            var strbyte = str.toByteArray(Charset.forName("utf-8"))
+            return sha256.digest(strbyte)
+        }
+
+        fun encrypt_privatezap_message(msg: String, privkey: ByteArray, pubkey: ByteArray): String {
+            var sharedSecret = Utils.getSharedSecret(privkey, pubkey)
+            val iv = ByteArray(16)
+            SecureRandom().nextBytes(iv)
+
+            val keySpec = SecretKeySpec(sharedSecret, "AES")
+            val ivSpec = IvParameterSpec(iv)
+
+            var utf8_message = 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 encryptedMsgBech32 = Bech32.encode("pzap", Bech32.eight2five(encryptedMsg), Bech32.Encoding.Bech32)
+            val ivBech32 = Bech32.encode("iv", Bech32.eight2five(iv), Bech32.Encoding.Bech32)
+
+            return encryptedMsgBech32 + "_" + ivBech32
+        }
+
+        fun decrypt_privatezap_message(msg: String, privkey: ByteArray, pubkey: ByteArray): String {
+            var sharedSecret = Utils.getSharedSecret(privkey, pubkey)
+            val parts = msg.split("_")
+            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 ""
+            }
+        }
         fun create(
             userHex: String,
             relays: Set<String>,
@@ -60,7 +118,7 @@ class LnZapRequestEvent(
             zapType: LnZapEvent.ZapType,
             createdAt: Long = Date().time / 1000
         ): LnZapRequestEvent {
-            val content = message
+            var content = message
             var privkey = privateKey
             var pubKey = Utils.pubkeyCreate(privateKey).toHexKey()
             var tags = listOf(
@@ -68,18 +126,24 @@ class LnZapRequestEvent(
                 listOf("relays") + relays
             )
             if (zapType == LnZapEvent.ZapType.ANONYMOUS) {
-                tags = tags + listOf(listOf("anon", ""))
                 privkey = Utils.privkeyCreate()
                 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 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))
+                content = ""
+                privkey = enc_prkey
+                pubKey = Utils.pubkeyCreate(enc_prkey).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())
         }
     }
 }
-
 /*
 {
   "pubkey": "32e1827635450ebb3c5a7d12c1f8e7b2b514439ac10a67eef3d9fd9c5c68e245",

app/src/main/java/com/vitorpamplona/amethyst/ui/note/ZapCustomDialog.kt

@@ -67,6 +67,7 @@ fun ZapCustomDialog(onClose: () -> Unit, account: Account, accountViewModel: Acc
 
     val zapTypes = listOf(
         Pair(LnZapEvent.ZapType.PUBLIC, "Public"),
+        Pair(LnZapEvent.ZapType.PRIVATE, "Private"),
         Pair(LnZapEvent.ZapType.ANONYMOUS, "Anonymous"),
         Pair(LnZapEvent.ZapType.NONZAP, "Non-Zap")
     )