A forward-secure append-only persistent authenticated data structure. This is a proof-of-concept implementation, please do not use for anything serious.
Balloon is composed of a history tree (like Certificate Transparency) and a hash treap (think authenticated index). Please read the paper for details. To run and reproduce parts of the benchmark from the paper, see the paper-bench branch.
Apache 2.0. The hash treap implementation is based on the treap implementation by Steve Yen under the MIT license.