chore: Add more comprehensive java test for add_commitment

bindings/java/java_code/src/test/java/verkle/cryptography/LibIpaMultipointTest.java

@@ -18,6 +18,8 @@
 import org.junit.jupiter.api.Test;
 import static org.assertj.core.api.Assertions.*;
 
+import java.math.BigInteger;
+
 import org.apache.tuweni.bytes.Bytes;
 import org.apache.tuweni.bytes.Bytes32;
 import verkle.cryptography.LibIpaMultipoint;
@@ -130,4 +132,59 @@ public void testAddCommitment() {
 
         assertThat(result).isEqualTo(expected);
     }
+
+    @Test
+    public void testGetTreeKeySubIndex0() {
+        // Taken from "get_tree_key_add_commitment_equivalence" test in rust ffi_interface
+        // code.
+        BigInteger[] chunkedInput = new BigInteger[] {
+                BigInteger.valueOf(16386),
+            new BigInteger("21345817372864405881847059188222722561"),
+            new BigInteger("42696867846335054569745073772176806417"),
+            new BigInteger("65392825175610104412738625059090743104"),
+            new BigInteger("44041774702139455724840610475136659248")
+        };
+
+        Bytes expectedHashForSubIndex0 = Bytes.fromHexString("ff7e3916badeb510dfcdad458726273319280742e553d8d229bd676428147300");
+
+        Bytes32 marker = toBytes32LE(chunkedInput[0]);
+        Bytes32 addressLow = toBytes32LE(chunkedInput[1]);
+        Bytes32 addressHigh = toBytes32LE(chunkedInput[2]);
+        Bytes32 treeIndexLow = toBytes32LE(chunkedInput[3]);
+        Bytes32 treeIndexHigh = toBytes32LE(chunkedInput[4]);
+
+        Bytes address = Bytes.concatenate(addressLow, addressHigh);
+        Bytes addressWithMarker = Bytes.concatenate(marker, address);
+        Bytes addressCached = Bytes.of(LibIpaMultipoint.commit(addressWithMarker.toArray()));
+
+        Bytes32 zero = Bytes32.fromHexString("0x0000000000000000000000000000000000000000000000000000000000000000");
+        Bytes32[] treeIndex = new Bytes32[5];
+        treeIndex[0] = zero;
+        treeIndex[1] = zero;
+        treeIndex[2] = zero;
+        treeIndex[3] = treeIndexLow;
+        treeIndex[4] = treeIndexHigh;
+        Bytes input = Bytes.concatenate(treeIndex);
+
+        Bytes treeIndexCommit = Bytes.wrap(LibIpaMultipoint.commit(input.toArray()));
+
+        byte[] committedPoint = LibIpaMultipoint.addCommitment(addressCached.toArray(), treeIndexCommit.toArray());
+
+        byte[] key = LibIpaMultipoint.hash(committedPoint);
+        key[31] = 0; // modify the last byte to simulate get_tree_key using sub_index=0
+
+        assertThat(Bytes.of(key)).isEqualTo(expectedHashForSubIndex0);
+    }
+
+    private static Bytes32 toBytes32LE(BigInteger value) {
+        byte[] bytes = new byte[32];
+        byte[] valueBytes = value.toByteArray();
+
+        // Copy in reverse order directly into the target array
+        for (int i = 0; i < valueBytes.length; i++) {
+            bytes[i] = valueBytes[valueBytes.length - 1 - i];
+        }
+
+        return Bytes32.wrap(bytes);
+    }
 }

ffi_interface/src/lib.rs

@@ -413,7 +413,7 @@
 
 #[cfg(test)]
 mod tests {
     use crate::{verify_execution_witness, Context};
     use banderwagon::Fr;
     use ipa_multipoint::committer::Committer;
     use verkle_trie::proof::golang_proof_format::{EXECUTION_WITNESS_JSON, PREVIOUS_STATE_ROOT};
@@ -422,7 +422,7 @@
 
     #[test]
     fn exec_witness_works() {
         let result = verify_execution_witness(PREVIOUS_STATE_ROOT, EXECUTION_WITNESS_JSON);
         assert!(result);
     }
 
@@ -520,8 +520,8 @@
 #[cfg(test)]
 mod pedersen_hash_tests {
 
     use banderwagon::Fr;
     use ipa_multipoint::committer::Committer;
 
     use crate::{
         add_commitment, commit_to_scalars, get_tree_key, get_tree_key_hash, hash_commitment,
@@ -541,7 +541,7 @@
     }
 
     #[test]
-    fn smoke_test_input() {
+    fn get_tree_key_add_commitment_equivalence() {
         let context = Context::default();
         let input = [
             1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,