fix: handle generic p-tags in NIP04 decrypt recipient check

nostr-java-api/src/main/java/nostr/api/NIP04.java

@@ -348,7 +348,7 @@ public static String decrypt(@NonNull Identity rcptId, @NonNull GenericEvent eve
             .or(() -> findGenericPubKeyTag(event))
             .orElseThrow(() -> new NoSuchElementException("No matching p-tag found."));
 
-    boolean rcptFlag = amITheRecipient(rcptId, event);
+    boolean rcptFlag = amITheRecipient(rcptId, event, pTag);
 
     if (!rcptFlag) { // I am the message sender
       log.debug("Decrypting own sent message");
@@ -386,14 +386,11 @@ private static PubKeyTag toPubKeyTag(BaseTag tag) {
         "Unsupported tag type for p-tag conversion: " + tag.getClass().getName());
   }
 
-  private static boolean amITheRecipient(@NonNull Identity recipient, @NonNull GenericEvent event) {
-    // Use helper to fetch the p-tag without manual casts
-    PubKeyTag pTag =
-        Filterable.getTypeSpecificTags(PubKeyTag.class, event).stream()
-            .findFirst()
-            .orElseThrow(() -> new NoSuchElementException("No matching p-tag found."));
-
-    if (Objects.equals(recipient.getPublicKey(), pTag.getPublicKey())) {
+  private static boolean amITheRecipient(
+      @NonNull Identity recipient,
+      @NonNull GenericEvent event,
+      @NonNull PubKeyTag resolvedPubKeyTag) {
+    if (Objects.equals(recipient.getPublicKey(), resolvedPubKeyTag.getPublicKey())) {
       return true;
     }
 

nostr-java-api/src/test/java/nostr/api/unit/NIP04Test.java

@@ -1,8 +1,10 @@
 package nostr.api.unit;
 
 import nostr.api.NIP04;
+import nostr.base.ElementAttribute;
 import nostr.base.Kind;
 import nostr.event.impl.GenericEvent;
+import nostr.event.tag.GenericTag;
 import nostr.event.tag.PubKeyTag;
 import nostr.id.Identity;
 import org.junit.jupiter.api.BeforeEach;
@@ -14,6 +16,8 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.util.List;
+
 /**
  * Unit tests for NIP-04 (Encrypted Direct Messages).
  *
@@ -152,6 +156,30 @@ public void testEncryptSpecialCharacters() {
     assertEquals(content, decrypted);
   }
 
+  @Test
+  // Ensures decrypt can resolve generic p-tags when determining the recipient.
+  public void testDecryptWithGenericPubKeyTagFallback() {
+    String content = "Generic tag ciphertext";
+
+    String encrypted = NIP04.encrypt(sender, content, recipient.getPublicKey());
+
+    GenericTag genericPTag =
+        new GenericTag(
+            "p",
+            List.of(new ElementAttribute("param0", recipient.getPublicKey().toString())));
+
+    GenericEvent event =
+        GenericEvent.builder()
+            .pubKey(sender.getPublicKey())
+            .kind(Kind.ENCRYPTED_DIRECT_MESSAGE)
+            .tags(List.of(genericPTag))
+            .content(encrypted)
+            .build();
+
+    String decrypted = NIP04.decrypt(recipient, event);
+    assertEquals(content, decrypted);
+  }
+
   @Test
   public void testDecryptInvalidEventKindThrowsException() {
     // Create a non-DM event