From f5ab7fdeb765ac46f3c333cd27ce8a720debc45d Mon Sep 17 00:00:00 2001
From: kngako <kpangako+github@gmail.com>
Date: Tue, 20 Aug 2024 01:39:22 +0200
Subject: [PATCH] Improve JNI handling of frost share gen

---
 .../fr_acinq_secp256k1_Secp256k1CFunctions.c  | 22 ++++++++++++-------
 .../fr/acinq/secp256k1/NativeSecp256k1.kt     | 12 ++++++----
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c b/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c
index 0e03ff4..4171a23 100644
--- a/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c
+++ b/jni/c/src/fr_acinq_secp256k1_Secp256k1CFunctions.c
@@ -1379,7 +1379,7 @@ JNIEXPORT jbyteArray JNICALL Java_fr_acinq_secp256k1_Secp256k1CFunctions_secp256
   jbyte *pubkeyBytes;
 
   unsigned char seed32[32];
-  unsigned char *ids33[jn_participants];
+  const jbyte *ids33[jn_participants];
 
   if (jctx == 0)
       return NULL;
@@ -1399,17 +1399,23 @@ JNIEXPORT jbyteArray JNICALL Java_fr_acinq_secp256k1_Secp256k1CFunctions_secp256
   copy_bytes_from_java(penv, jseed32, size, seed32);
 
   size = (*penv)->GetArrayLength(penv, jids33);
-  CHECKRESULT(size != jn_participants, "invalid ids33 size");
+  CHECKRESULT(size != jn_participants, "ids33 needs to be of size jn_participants");
 
   CHECKRESULT((*penv)->GetArrayLength(penv, jpok64) != 64, "pok64 length must be 64 bytes");
 
+//  for (i = 0; i < jn_participants; i++)
+//  {
+//    jbyteArray jid33 = (jbyteArray)(*penv)->GetObjectArrayElement(penv, jids33, i);
+//    size = (*penv)->GetArrayLength(penv, jid33);
+//    CHECKRESULT(size != 33, "invalid id33 size");
+//    copy_bytes_from_java(penv, jid33, 33, ids33[i]);
+//  }
   for (i = 0; i < jn_participants; i++)
-  {
-    jbyteArray jid33 = (jbyteArray)(*penv)->GetObjectArrayElement(penv, jids33, i);
-    size = (*penv)->GetArrayLength(penv, jid33);
-    CHECKRESULT(size != 33, "invalid id33 size");
-    copy_bytes_from_java(penv, jid33, 33, ids33[i]);
-  }
+    {
+      jbyteArray id33 = (jbyteArray)(*penv)->GetObjectArrayElement(penv, jids33, i);
+      // TODO: Check id33 size is 33...
+      ids33[i] = (*penv)->GetByteArrayElements(penv, id33, 0);
+    }
 
   int sharesLength = jn_participants * 32;
   int vssCommitmentLength = jthreshold * 65;
diff --git a/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt b/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt
index 5c704d8..a79125d 100644
--- a/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt
+++ b/jni/src/main/kotlin/fr/acinq/secp256k1/NativeSecp256k1.kt
@@ -145,18 +145,22 @@ public object NativeSecp256k1 : Secp256k1 {
             totalSigners,
             ids33
         )
+        println(Hex.encode(result))
+
         val shares = Array(totalSigners) { index ->
             val startIndex = 0 + (index*32);
-            val endIndex = 32 + (index*32);
+            val endIndex = 31 + (index*32);
 
             result.sliceArray(
                 startIndex..endIndex
             )
         }
 
-        val vssCommitment = Array(totalSigners) { index ->
-            val startIndex = 0 + (index*65);
-            val endIndex = 65 + (index*65);
+        val sharesOffset = totalSigners*32;
+
+        val vssCommitment = Array(threshold) { index ->
+            val startIndex = sharesOffset + (index*65);
+            val endIndex = sharesOffset + 64 + (index*65);
 
             result.sliceArray(
                 startIndex..endIndex