Proof-carrying data (PCD)

This arkworks library describes an interface and contains an implementation for proof-carrying data (PCD).

PCD (introduced in [CT10]) is a cryptographic primitive that allows the incremental verification of a distributed computation that can continue indefinitely. A computation defined by a (possibly infinite) directed acyclic graph is augmented by attaching a succinct proof of correctness to each message, allowing any intermediate state of the computation to be verified efficiently. PCD is a generalization of IVC [Val08], or incrementally-verifiable computation, which is PCD in the case of a linear computation (that is, the graph is a path graph).

This library is released under the MIT License and the Apache v2 License (see License).

WARNING: This is an academic proof-of-concept prototype, and in particular has not received careful code review. This implementation is NOT ready for production use.

The PCD interface is here and relies on a cycle of elliptic curves (e.g. the MNT cycle). Separate CircuitSpecificSetupPCD and UniversalSetupPCD interfaces are included depending on the underlying SNARK type(s). Note that the underlying main SNARK and helper SNARK do not have to be the same, although both must implement either CircuitSpecificSetupSNARK or UniversalSetupSNARK.

Build guide

The library compiles on the stable toolchain of the Rust compiler. To install the latest version of Rust, first install rustup by following the instructions here, or via your platform's package manager. Once rustup is installed, install the Rust toolchain by invoking: bash rustup install stable

After that, use cargo, the standard Rust build tool, to build the libraries: bash git clone https://github.com/arkworks-rs/pcd.git cd pcd cargo build

Tests

This library comes with comprehensive unit and integration tests. Run the tests with: bash cargo test --all

License

The crates in this repo are licensed under either of the following licenses, at your discretion.

• Apache License Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

Unless you explicitly state otherwise, any contribution submitted for inclusion in this library by you shall be dual licensed as above (as defined in the Apache v2 License), without any additional terms or conditions.

References

[CT10] Proof-Carrying Data and Hearsay Arguments from Signature Cards
Alessandro Chiesa and Eran Tromer
ITCS 2010

[Val08] Incrementally Verifiable Computation or Proofs of Knowledge Imply Time/Space Efficiency
Paul Valiant
TCC 2008