diff --git a/lib/src/event.dart b/lib/src/event.dart
index 2748f4b..96f7c25 100644
--- a/lib/src/event.dart
+++ b/lib/src/event.dart
@@ -128,27 +128,26 @@ class Event {
     );
   }
 
-  /// Instantiate Event object from the minimum available data
+  /// Instantiate Event object from the minimum needed data
   ///
   /// ```dart
   ///Event event = Event.from(
   ///  kind: 1,
-  ///  tags: [],
   ///  content: "",
   ///  privkey:
   ///      "5ee1c8000ab28edd64d74a7d951ac2dd559814887b1b9e1ac7c5f89e96125c12",
   ///);
   ///```
   factory Event.from({
-    int createdAt = 0,
+    int? createdAt,
     required int kind,
-    required List<List<String>> tags,
+    List<List<String>> tags = const [],
     required String content,
     required String privkey,
     String? subscriptionId,
     bool verify = false,
   }) {
-    if (createdAt == 0) createdAt = currentUnixTimestampSeconds();
+    createdAt ??= currentUnixTimestampSeconds();
     final pubkey = bip340.getPublicKey(privkey).toLowerCase();
 
     final id = _processEventId(
@@ -271,20 +270,6 @@ class Event {
     );
   }
 
-  factory Event.quick(
-    String content,
-    String privkey,
-  ) {
-    Event event = Event.partial();
-    event.kind = 1;
-    event.content = content;
-    event.createdAt = currentUnixTimestampSeconds();
-    event.pubkey = bip340.getPublicKey(privkey).toLowerCase();
-    event.id = event.getEventId();
-    event.sig = event.getSignature(privkey);
-    return event;
-  }
-
   /// To obtain the event.id, we sha256 the serialized event.
   /// The serialization is done over the UTF-8 JSON-serialized string (with no white space or line breaks) of the following structure:
   ///
diff --git a/lib/src/nips/nip_004/crypto.dart b/lib/src/nips/nip_004/crypto.dart
index f342b87..3dbdbb0 100644
--- a/lib/src/nips/nip_004/crypto.dart
+++ b/lib/src/nips/nip_004/crypto.dart
@@ -64,9 +64,9 @@ class Nip4 {
   static String decipher(
     String privkey,
     String pubkey,
-    String ciphertext, [
-    String nonce = "",
-  ]) {
+    String ciphertext,
+    String nonce,
+  ) {
     Uint8List cipherText = base64.decode(ciphertext);
     List<List<int>> byteSecret = gMapByteSecret[pubkey] ?? [];
     if (byteSecret.isEmpty) {
diff --git a/lib/src/nips/nip_004/event.dart b/lib/src/nips/nip_004/event.dart
index f437f03..ce46119 100644
--- a/lib/src/nips/nip_004/event.dart
+++ b/lib/src/nips/nip_004/event.dart
@@ -4,8 +4,6 @@ import 'package:nostr/src/nips/nip_004/crypto.dart';
 import 'package:nostr/src/utils.dart';
 
 class EncryptedDirectMessage extends Event {
-  static Map<String, List<List<int>>> gMapByteSecret = {};
-
   EncryptedDirectMessage(Event event)
       : super(
           event.id,
@@ -39,28 +37,24 @@ class EncryptedDirectMessage extends Event {
 
   String? get receiverPubkey => findPubkey();
 
+  String get nonce {
+    List<String> split = content.split("?iv=");
+    if (split.length != 2) throw Exception("invalid nip4 content");
+    return split[1];
+  }
+
   String getCiphertext(String senderPrivkey, String receiverPubkey) {
-    String ciphertext =
-        Nip4.cipher(senderPrivkey, '02$receiverPubkey', content);
-    return ciphertext;
+    return Nip4.cipher(senderPrivkey, '02$receiverPubkey', content);
   }
 
-  String getPlaintext(String receiverPrivkey, [String senderPubkey=""]) {
-    if (senderPubkey.length == 0) {
-      senderPubkey = pubkey;
-    }
+  String getPlaintext(String receiverPrivkey) {
+    String ciphertext = content.split("?iv=")[0];
     String plaintext = "";
-    int ivIndex = content.indexOf("?iv=");
-    if( ivIndex <= 0) {
-      print("Invalid content for dm, could not get ivIndex: $content");
-      return plaintext;
-    }
-    String iv = content.substring(ivIndex + "?iv=".length, content.length);
-    String ciphertext = content.substring(0, ivIndex);
     try {
-      plaintext = Nip4.decipher(receiverPrivkey, "02$senderPubkey", ciphertext, iv);
-    } catch(e) {
-      print("Fail to decrypt: ${e}");
+      plaintext =
+          Nip4.decipher(receiverPrivkey, "02$pubkey", ciphertext, nonce);
+    } catch (e) {
+      throw Exception("Fail to decipher: $e");
     }
     return plaintext;
   }