Crums Timechain (Alpha)

Welcome to the first release of the Crums Timechain, a key-less solution for generating cryptographic timestamps at scale. Conceptually, a timechain is a chain of 64-byte blocks, generated at a constant, steady rate (set at inception), using a cryptographic commitment scheme that records evidence about when things (as represented by their SHA-256 hashes) occur. The project documentation page details a conceptual overview of timechains and how their proof structures work.

The project is organized in 4 modules, listed below. The last 2, are end-user programs.

1. timechain - Defines the basic timechain, and its proof structures. Additionally, it provides client-side code for accessing a timechain.
2. notary - Background daemon service that collects crums (witnessed hashes) and publishes their collective hash per block (time bin) interval as the cargo hash of the corresponding timechain block. The notary is designed to be safe under concurrent read/write access from multiple processes (not just threads).
3. ergd - Embedded HTTP REST server launched from the command line. New chains can also be incepted (created) thru this CLI.
4. crum - Client-side CLI for remote timechains. Archives receipts (called crumtrails) in a user repo.

Building from source

The project's build tool is Maven. It uses Java's new virtual threads, so JDK 22 is a minimum requirement.

Clone the following repositories (in addition to this repo):

1. merkle-tree - Merkle tree implementation.
2. io-util - Multi-module utilies.
3. stowkwik - Hash filepath object store.
4. skipledger - Commitment scheme.

Build those repos in the above order, using

$ mvn clean install

The last build, skipledger, succeeds in building the base submodule skipledger-base but fails to build related submodules. You can ignore those build failures.

(The skipledger submodules that don't build, depend on an older versions of this repo. That legacy code is now archived under the TC-1 subdirectory here in this repo. If you build the legacy TC-1 in this repo first, then all skipledger submodules should build. They will be retrofitted to use this new timechain in subsequent releases.)

Next, build this project's library modules (in their respective subdirectories) in the following order:

1. timechain. Base library both clients and server know about.
2. notary. Server-side engine.

Finally, build the 2 deliverables

• ergd. Timechain server launch CLI, and
• crum. Multi-chain client CLI with local (crumtrail) repo

using

$ mvn clean package appassembler:assemble

In their respective subdirectories, give these a try:

./target/binary/bin/ergd -h

./target/binary/bin/crum -h

~ Babak

December 2024