Skip to content

fix: 21882: Corner cases for merkle tree hashing #21910

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 5, 2025
Merged

fix: 21882: Corner cases for merkle tree hashing #21910

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 10 additions & 4 deletions .../swirlds-virtualmap/src/main/java/com/swirlds/virtualmap/internal/hash/VirtualHasher.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
import com.swirlds.virtualmap.internal.Path;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.security.MessageDigest;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
Expand Down Expand Up @@ -213,7 +214,7 @@ protected boolean onExecute() {
if (right == null) {
final long rightPath = rankPath + i * 2 + 1;
right = hashReader.apply(rightPath);
if ((right == null) && (rightPath != 2)) {
if (right == null) {
throw new RuntimeException("Failed to load hash for path = " + rightPath);
}
}
Expand All @@ -233,8 +234,11 @@ protected boolean onExecute() {
static Hash hash(final Hash left, final Hash right) {
final WritableMessageDigest wmd = MESSAGE_DIGEST_THREAD_LOCAL.get();
wmd.reset();
// Unique value to make sure internal node hashes are different from leaf hashes
wmd.writeByte((byte) 0x02);
// Unique value to make sure internal node hashes are different from leaf hashes. This
// value indicates the number of child nodes. All internal virtual nodes have 2 children
// except a root node in a tree with just one element / leaf. In this and only this case,
// the right hash will be set to a marker NO_PATH2_HASH hash object
wmd.writeByte(right == NO_PATH2_HASH ? (byte) 0x01 : (byte) 0x02);
left.getBytes().writeTo(wmd);
if (right != NO_PATH2_HASH) { // use identity check rather than equals
right.getBytes().writeTo(wmd);
Expand Down Expand Up @@ -642,6 +646,8 @@ private Hash hashInternal(
}

public Hash emptyRootHash() {
return ChunkHashTask.hash(Cryptography.NULL_HASH, Cryptography.NULL_HASH);
final MessageDigest md = Cryptography.DEFAULT_DIGEST_TYPE.buildDigest();
md.update((byte) 0x00);
return new Hash(md.digest(), Cryptography.DEFAULT_DIGEST_TYPE);
}
}
2 changes: 1 addition & 1 deletion ...-virtualmap/src/test/java/com/swirlds/virtualmap/internal/hash/VirtualHasherTestBase.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,7 @@ protected static VirtualHashRecord hashSubTree(

// This has to match VirtualHasher
md.reset();
md.update((byte) 0x02);
md.update(rightHash == null ? (byte) 0x01 : (byte) 0x02);
leftHash.getBytes().writeTo(md);
if (rightHash != null) {
rightHash.getBytes().writeTo(md);
Expand Down
Loading