mpc

This is a multi-party computation protocol for the key-generation step of Pinocchio zkSNARKs [PGHR13] designed for use in the Zcash "Sprout" public parameter ceremony.

Zcash Ceremony

The public parameters (zk-SNARK proving and verifying keys) for Zcash's 1.0 "Sprout" launch were constructed in a ceremony that took place on October 22-23.

The following individuals participated in the ceremony:

• Andrew Miller
• Peter Van Valkenberg
• John Dobbertin
• Zooko Wilcox
• Derek Hinch
• Fabrice Renault

The ceremony used a multi-party computation protocol with the property that the resulting parameters are secure unless all of the participants were dishonest or compromised during the ceremony.

Assets

r1cs: 6111c2bce234867201d887170d68712c8f8785a1c97d43ab4ca540d7704ee8f7

transcript: 7da0c07a4bec04fbe4ae99ebd62d4ce7e1710b1f7a1f317345b0a48feec984d3

sprout-proving.key: 8bc20a7f013b2b58970cddd2e7ea028975c88ae7ceb9259a5344a16bc2c0eef7

sprout-verifying.key: 4bd498dae0aacfd8e98dc306338d017d9c08dd0918ead18172bd0aec2fc5df82

finalmpc2-compute.iso: 5f43aa1244a01b3cf9da4abeadde9e34b954a873565fc56b58c10780f3ce0e4c

finalmpc2-network.iso: 375550be4c64ebc68a9306421bb71ad3556bc73f156a231503084f923900f4cb

r1cs

This is the rank-1 quadratic constraint system used by Zcash. You can use Zcash to construct it with the following PR: https://github.com/zcash/zcash/pull/1399.

transcript

This is a transcript of the protocol that can be used to verify the protocol's evaluation and construct the proving/verifying keys.

sprout-*.key

These are the final parameters that can be built from the transcript.

finalmpc2-*.iso

These are reproducibly generated Live CD images used during the ceremony, using a modified Alpine Linux distribution.

Code and verification

The code used for the ceremony was tagged at finalmpc2.

ISOs

The participants all booted from the finalmpc2-compute.iso on hardware they obtained securely. It can be reproducibly built using the build-iso.sh tool. Some of the participants also used finalmpc2-network.iso for the networking during the ceremony, though it was not necessary.

Transcript verification

Given r1cs and transcript, and powerful enough hardware, you can verify the protocol transcript and construct pk/vk within a few hours. Run cargo run --release --bin verifier.

Here is the log from verifying the transcript:

Number of players: 6
Player 1 commitment: 2iQQBkf7k4K9aigJm4uHHufaSB8rXLLaRTMmTerK7dx6RCqNc9
Player 2 commitment: 6yV3Ji7zuVWVCQEfkhQ6Vfv51t5VfQHQVaLDGH6zkeunKmohr
Player 3 commitment: 6mGvvMFMKJNwKFmHXUwcCQMk7iu92bSqhtRabX3nkdnadEKte
Player 4 commitment: VGyYjzYc39em9TithdWFySSUwATMgcXcLtQ7ias7i4SkNdS4G
Player 5 commitment: 2YrFsjMadFukhdkQpn8oFgET2EQd9WnDW3AzYqNc3kELU45p7t
Player 6 commitment: 2B2HXuZAKayqgJpxojuUU9RN78pTv2gLvEDmEbWRBWEJ6Z1LS
Player 1 hash of disk A: 2oX6hBNiQxiZYZgDbSkgk3mhBACXmoGCfdhfZrSquNztZuZaqt
Player 1 hash of disk B: 2T2ceUDomnrCVCtJw2SwtYAeHCfnAhM9HBdzVkq6BdZ59nST5m
Player 2 hash of disk A: 2axdkGL6QzngjvY9jRBX5AqhSokukji8eQuYUfJwhp7sxcXvPr
Player 2 hash of disk B: 2RymyNbAWaBVDuzW4m1iKA72MsmZFnwMhNvqxxXDwugLTa62wc
Player 3 hash of disk A: YAQs9PiruKxfTwMTdTUHkYgt9QRvjpkF95cJRbNP8WLqPqjLW
Player 3 hash of disk B: 2omA7bsepmmxeygQzNBbodhdXTyhuK1i2KCRH9esB3azunwZPn
Player 4 hash of disk A: EDEtkk1PUhu4BQbTzx5yPSSpyqB6kV9g39p6sNt1ERGRG3APQ
Player 4 hash of disk B: 2fvnbP22XWHVD1DstGQ5FsHNaBLiZQg4MBVKmWf7sWCYg5A9L7
Player 5 hash of disk A: 2oQgZxPLAL2f8xkvm71RqwKK6dCFQSrazESXci32M2LZeG7nxe
Player 5 hash of disk B: UBjr6UU8oJ4ZzpsTU3vRHmzZmuN7TjX3eLsmdRhw4dW6dEbvH
Player 6 hash of disk A: rnMAJE2bxMbCT6yRvufD2ww17kmP9qaKnipxrvZTWXe27d6GW
Player 6 hash of disk B: 27Em5cp6QSGVsJsAcvZLW7CoMkKv5Ybi3LAGPPeGwqCF7Diex
Player 1 hash of disk C: 29PLu7dtT9BjJhtoAzxpSxvrp4tE15xjJufL1ANHGwkwieyxMo
Player 1 hash of disk D: 2YVAELKtHdufKRPTzT5ZpHFgxrcro6JmBKkYz4GEQqcXbQdViM
Player 2 hash of disk C: 2qSQhJvQLjmXfQWHKMCR5EukSWU9BQ3KwdPSqkPUCSRzwmxowM
Player 2 hash of disk D: 2uAxySzeptYhEowKuBRGituPnc1U4BU1GMuL4Hfbyvtgq7x4Qn
Player 3 hash of disk C: 2DZ3pnkZcTMfAa28KfJpD5fQbnkQZZG5mFnFqvHHUDXJquSJAX
Player 3 hash of disk D: 2tfcauKUDBirJFSo8jbyEenLfHULThsQjVdN8FY3hJGn3dC2JP
Player 4 hash of disk C: 2gH6XJ8BeA5yXZL95ThSp9ucicwAoevaDK6xNBck9QUxXF1gEE
Player 4 hash of disk D: VFXKdDoYrA58evyJUrvkocGCHVvYF2h8HVLmuEtFkDfZY6EHk
Player 5 hash of disk C: 2RvKUp94tXE5b1qhyLpGPTXeWpS7FdNDvCG5MJPmZiccNuRYcw
Player 5 hash of disk D: ApPFWMqGBMemE3sTAuMRnwbmGonsPoXYC4r45HBMdmiRWLXqH
Player 6 hash of disk C: 2wGGYBXaeQdbLHvViArnLkGRERhztVk5qZmreSKwxEcFjMBNMC
Player 6 hash of disk D: 2g3rMWwyCL5wgKYHiVHR6EdnBc9Q5dPc1RW6tWwvwyJnx6AKq9
Player 1 hash of disk E: 2Zbrd1XhYKvZqeNcGQPVrusx1rRjxaQjFfzWcn64wCfTnEGTMg
Player 1 hash of disk F: 27ZzVxLTxXpjeTo86sdQ9kKU83UfNHLyGPuQ4CCV9ZRJ4g84jC
Player 2 hash of disk E: YWKCeTeYiKUNnd4aJBYcd8ZwBxscibmtDa4pxbz52fpYX2H9S
Player 2 hash of disk F: 2o1wWJHYzCirDmijHmnGFQ4pSfoYTkEKdPinag22eYonKf8EGC
Player 3 hash of disk E: 2jquuLB8omrtWV1GnXvghRN1A3MWMouyBSwEKD5fCMwk5SvktP
Player 3 hash of disk F: 2jrEGwnSyX9oX8UUGYhpEiPaLmGmrbhfFtcciXt3o5N7nPh63A
Player 4 hash of disk E: AY1Vm8dDSxDdpNhac8Mr7GkS18vomvXaoreg1mVcXyApmgbu8
Player 4 hash of disk F: 2RVi4vpjXtzD6gPLsFDSVrtX545HbVnNBhjAJVUTXpG22oLDD5
Player 5 hash of disk E: CFEWpN9STr4iVM8NLGcSUyoaEDr94FEp7VWR9HhQQYhuwUu7f
Player 5 hash of disk F: 2vohW4tyybTEZyf3ZarX5R1CgsUehQfwASExZQ86EWNd8ByC6a
Player 6 hash of disk E: chZdF1yRVDTsaD14KdaFv6N7e8ZPkMnxr9CpXkzq8JzonhLPx
Player 6 hash of disk F: 2HjRqGyKjPxDSbhP8KgyYtKpWCwrGt3v4ZEUZHsZpJHbJ2V9QL

License

Licensed under either of

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

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Authors

• Sean Bowe
• Ariel Gabizon
• Matthew Green