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// -*- mode: rust; -*- // // This file is part of ed25519-dalek. // Copyright (c) 2017-2019 isis lovecruft // See LICENSE for licensing information. // // Authors: // - isis agora lovecruft <isis@patternsinthevoid.net> //! A Rust implementation of **[FROST]**: **F**lexible **R**ound-**O**ptimised **S**chnorr **T**hreshold signatures. //! //! Threshold signatures are a cryptographic construction wherein a subset, \\( t \\), //! of a group of \\( n \\) signers can produce a valid signature. For example, if //! Alice, Bob, and Carol set up key materials for a 2-out-of-3 threshold signature //! scheme, then the same public group key can be used to verify a message signed //! by Alice and Carol as a different message signed by Bob and Carol. //! //! FROST signatures are unique in that they manage to optimise threshold signing into //! a single round, while still safeguarding against [various] [cryptographic] [attacks] //! that effect other threshold signing schemes, by utilising [commitments] to //! pre-computed secret shares. //! //! For a more in-depth explanation of the mathematics involved, please see //! [here](keygen/index.html), [here](precomputation/index.html), and //! [here](signature/index.html). //! //! [FROST]: https://eprint.iacr.org/2020/852 //! [various]: https://eprint.iacr.org/2018/417 //! [cryptographic]: https://eprint.iacr.org/2020/945 //! [attacks]: https://www.researchgate.net/profile/Claus_Schnorr/publication/2900710_Security_of_Blind_Discrete_Log_Signatures_against_Interactive_Attacks/links/54231e540cf26120b7a6bb47.pdf //! [commitments]: https://en.wikipedia.org/wiki/Commitment_scheme //! //! # Usage //! //! Alice, Bob, and Carol would like to set up a threshold signing scheme where //! at least two of them need to sign on a given message to produce a valid //! signature. //! //! ```rust //! use frost_dalek::Parameters; //! //! let params = Parameters { t: 2, n: 3 }; //! ``` //! //! ## Distributed Key Generation //! //! Alice, Bob, and Carol each generate their secret polynomial coefficients //! (which make up each individual's personal secret key) and commitments to //! them, as well as a zero-knowledge proof of their personal secret key. Out //! of scope, they each need to agree upon their *participant index* which is //! some non-zero integer unique to each of them (these are the `1`, `2`, and //! `3` in the following examples). //! //! ```rust //! # use frost_dalek::Parameters; //! use frost_dalek::Participant; //! # //! # let params = Parameters { t: 2, n: 3 }; //! //! let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! ``` //! //! They send these values to each of the other participants (also out of scope //! for this library), or otherwise publish them publicly somewhere. //! //! ```rust //! # // This comment is here just to silence the "this code block is empty" warning. //! // send_to_bob(alice); //! // send_to_carol(alice); //! // send_to_alice(bob); //! // send_to_carol(bob); //! // send_to_alice(carol); //! // send_to_bob(carol); //! ``` //! //! Note that they should only send the `alice`, `bob`, and `carol` structs, *not* //! the `alice_coefficients`, etc., as the latter are their personal secret keys. //! //! Bob and Carol verify Alice's zero-knowledge proof by doing: //! //! ```rust //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! alice.proof_of_secret_key.verify(&alice.index, &alice.public_key().unwrap())?; //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! Similarly, Alice and Carol verify Bob's proof: //! //! ```rust //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! bob.proof_of_secret_key.verify(&bob.index, &bob.public_key().unwrap())?; //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! And, again, Alice and Bob verify Carol's proof: //! //! ```rust //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! carol.proof_of_secret_key.verify(&carol.index, &carol.public_key().unwrap())?; //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! Alice enters round one of the distributed key generation protocol: //! //! ```rust //! use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), Vec<u32>> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! //! let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! &mut alice_other_participants)?; //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! Alice then collects the secret shares which they send to the other participants: //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! let alice_their_secret_shares = alice_state.their_secret_shares()?; //! //! // send_to_bob(alice_their_secret_shares[0]); //! // send_to_carol(alice_their_secret_shares[1]); //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! Bob and Carol each do the same: //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), Vec<u32>> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! &mut bob_other_participants)?; //! # Ok(()) } //! # fn do_test2() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! //! let bob_their_secret_shares = bob_state.their_secret_shares()?; //! //! // send_to_alice(bob_their_secret_shares[0]); //! // send_to_carol(bob_their_secret_shares[1]); //! # Ok(()) } fn main() { assert!(do_test().is_ok()); assert!(do_test2().is_ok()); } //! ``` //! //! and //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), Vec<u32>> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! &mut carol_other_participants)?; //! # Ok(()) } //! # fn do_test2() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! //! let carol_their_secret_shares = carol_state.their_secret_shares()?; //! //! // send_to_alice(carol_their_secret_shares[0]); //! // send_to_bob(carol_their_secret_shares[1]); //! # Ok(()) } fn main() { assert!(do_test().is_ok()); assert!(do_test2().is_ok()); } //! ``` //! //! Each participant now has a vector of secret shares given to them by the other participants: //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares()?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares()?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares()?; //! let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! carol_their_secret_shares[0].clone()); //! let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! carol_their_secret_shares[1].clone()); //! let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! bob_their_secret_shares[1].clone()); //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! The participants then use these secret shares from the other participants to advance to //! round two of the distributed key generation protocol. //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares()?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares()?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares()?; //! # let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! # carol_their_secret_shares[0].clone()); //! # let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! # carol_their_secret_shares[1].clone()); //! # let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! # bob_their_secret_shares[1].clone()); //! # //! let alice_state = alice_state.to_round_two(alice_my_secret_shares)?; //! let bob_state = bob_state.to_round_two(bob_my_secret_shares)?; //! let carol_state = carol_state.to_round_two(carol_my_secret_shares)?; //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! Each participant can now derive their long-lived, personal secret keys and the group's //! public key. They should all derive the same group public key. They //! also derive their [`IndividualPublicKey`]s from their [`IndividualSecretKey`]s. //! //! ```rust //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares()?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares()?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares()?; //! # let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! # carol_their_secret_shares[0].clone()); //! # let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! # carol_their_secret_shares[1].clone()); //! # let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! # bob_their_secret_shares[1].clone()); //! # //! # let alice_state = alice_state.to_round_two(alice_my_secret_shares)?; //! # let bob_state = bob_state.to_round_two(bob_my_secret_shares)?; //! # let carol_state = carol_state.to_round_two(carol_my_secret_shares)?; //! # //! let (alice_group_key, alice_secret_key) = alice_state.finish(alice.public_key().unwrap())?; //! let (bob_group_key, bob_secret_key) = bob_state.finish(bob.public_key().unwrap())?; //! let (carol_group_key, carol_secret_key) = carol_state.finish(carol.public_key().unwrap())?; //! //! assert!(alice_group_key == bob_group_key); //! assert!(carol_group_key == bob_group_key); //! //! let alice_public_key = alice_secret_key.to_public(); //! let bob_public_key = bob_secret_key.to_public(); //! let carol_public_key = carol_secret_key.to_public(); //! # Ok(()) } fn main() { assert!(do_test().is_ok()); } //! ``` //! //! ## Precomputation and Partial Signatures //! //! Alice, Bob, and Carol can now create partial threshold signatures over an agreed upon //! message with their respective secret keys, which they can then give to an untrusted //! [`SignatureAggregator`] (which can be one of the participants) to create a //! 2-out-of-3 threshold signature. To do this, they each pre-compute (using //! [`generate_commitment_share_lists`]) and publish a list of commitment shares. //! //! ```rust //! # #[cfg(feature = "std")] //! use frost_dalek::compute_message_hash; //! # #[cfg(feature = "std")] //! use frost_dalek::generate_commitment_share_lists; //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # #[cfg(feature = "std")] //! use frost_dalek::SignatureAggregator; //! //! use rand::rngs::OsRng; //! # #[cfg(feature = "std")] //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares()?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares()?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares()?; //! # let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! # carol_their_secret_shares[0].clone()); //! # let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! # carol_their_secret_shares[1].clone()); //! # let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! # bob_their_secret_shares[1].clone()); //! # //! # let alice_state = alice_state.to_round_two(alice_my_secret_shares)?; //! # let bob_state = bob_state.to_round_two(bob_my_secret_shares)?; //! # let carol_state = carol_state.to_round_two(carol_my_secret_shares)?; //! # //! # let (alice_group_key, alice_secret_key) = alice_state.finish(alice.public_key().unwrap())?; //! # let (bob_group_key, bob_secret_key) = bob_state.finish(bob.public_key().unwrap())?; //! # let (carol_group_key, carol_secret_key) = carol_state.finish(carol.public_key().unwrap())?; //! # //! # let alice_public_key = alice_secret_key.to_public(); //! # let bob_public_key = bob_secret_key.to_public(); //! # let carol_public_key = carol_secret_key.to_public(); //! //! let (alice_public_comshares, mut alice_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 1, 1); //! let (bob_public_comshares, mut bob_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 2, 1); //! let (carol_public_comshares, mut carol_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 3, 1); //! //! // Each application developer should choose a context string as unique to their usage as possible, //! // in order to provide domain separation from other applications which use FROST signatures. //! let context = b"CONTEXT STRING STOLEN FROM DALEK TEST SUITE"; //! let message = b"This is a test of the tsunami alert system. This is only a test."; //! //! // Every signer should compute a hash of the message to be signed, along with, optionally, //! // some additional context, such as public information about the run of the protocol. //! let message_hash = compute_message_hash(&context[..], &message[..]); //! //! let mut aggregator = SignatureAggregator::new(params, bob_group_key.clone(), &context[..], &message[..]); //! # Ok(()) } //! # #[cfg(feature = "std")] //! # fn main() { assert!(do_test().is_ok()); } //! # #[cfg(not(feature = "std"))] //! # fn main() { } //! ``` //! //! The aggregator takes note of each expected signer for this run of the protocol. For this run, //! we'll have Alice and Carol sign. //! //! ```rust //! # #[cfg(feature = "std")] //! # use frost_dalek::compute_message_hash; //! # #[cfg(feature = "std")] //! # use frost_dalek::generate_commitment_share_lists; //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::IndividualPublicKey; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # #[cfg(feature = "std")] //! # use frost_dalek::SignatureAggregator; //! # //! # use rand::rngs::OsRng; //! # //! # #[cfg(feature = "std")] //! # fn do_test() -> Result<(), ()> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(()))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares()?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(()))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares()?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(()))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares()?; //! # let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! # carol_their_secret_shares[0].clone()); //! # let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! # carol_their_secret_shares[1].clone()); //! # let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! # bob_their_secret_shares[1].clone()); //! # //! # let alice_state = alice_state.to_round_two(alice_my_secret_shares)?; //! # let bob_state = bob_state.to_round_two(bob_my_secret_shares)?; //! # let carol_state = carol_state.to_round_two(carol_my_secret_shares)?; //! # //! # let (alice_group_key, alice_secret_key) = alice_state.finish(alice.public_key().unwrap())?; //! # let (bob_group_key, bob_secret_key) = bob_state.finish(bob.public_key().unwrap())?; //! # let (carol_group_key, carol_secret_key) = carol_state.finish(carol.public_key().unwrap())?; //! # //! # let alice_public_key = alice_secret_key.to_public(); //! # let bob_public_key = bob_secret_key.to_public(); //! # let carol_public_key = carol_secret_key.to_public(); //! # //! # let (alice_public_comshares, mut alice_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 1, 1); //! # let (bob_public_comshares, mut bob_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 2, 1); //! # let (carol_public_comshares, mut carol_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 3, 1); //! # //! # let context = b"CONTEXT STRING STOLEN FROM DALEK TEST SUITE"; //! # let message = b"This is a test of the tsunami alert system. This is only a test."; //! # //! # let message_hash = compute_message_hash(&context[..], &message[..]); //! # //! # let mut aggregator = SignatureAggregator::new(params, bob_group_key.clone(), &context[..], &message[..]); //! # //! aggregator.include_signer(1, alice_public_comshares.commitments[0], alice_public_key); //! aggregator.include_signer(3, carol_public_comshares.commitments[0], carol_public_key); //! # Ok(()) } //! # #[cfg(feature = "std")] //! # fn main() { assert!(do_test().is_ok()); } //! # #[cfg(not(feature = "std"))] //! # fn main() { } //! ``` //! //! The aggregator should then publicly announce which participants are expected to be signers. //! //! ```rust,ignore //! let signers = aggregator.get_signers(); //! ``` //! //! Alice and Carol each then compute their partial signatures, and send these to the signature aggregator. //! //! ```rust //! # #[cfg(feature = "std")] //! # use frost_dalek::compute_message_hash; //! # #[cfg(feature = "std")] //! # use frost_dalek::generate_commitment_share_lists; //! # use frost_dalek::DistributedKeyGeneration; //! # use frost_dalek::Parameters; //! # use frost_dalek::Participant; //! # #[cfg(feature = "std")] //! # use frost_dalek::SignatureAggregator; //! # //! # use rand::rngs::OsRng; //! # //! # #[cfg(feature = "std")] //! # fn do_test() -> Result<(), &'static str> { //! # let params = Parameters { t: 2, n: 3 }; //! # //! # let (alice, alice_coefficients) = Participant::new(¶ms, 1); //! # let (bob, bob_coefficients) = Participant::new(¶ms, 2); //! # let (carol, carol_coefficients) = Participant::new(¶ms, 3); //! # //! # let mut alice_other_participants: Vec<Participant> = vec!(bob.clone(), carol.clone()); //! # let alice_state = DistributedKeyGeneration::<_>::new(¶ms, &alice.index, &alice_coefficients, //! # &mut alice_other_participants).or(Err(""))?; //! # let alice_their_secret_shares = alice_state.their_secret_shares().or(Err(""))?; //! # //! # let mut bob_other_participants: Vec<Participant> = vec!(alice.clone(), carol.clone()); //! # let bob_state = DistributedKeyGeneration::<_>::new(¶ms, &bob.index, &bob_coefficients, //! # &mut bob_other_participants).or(Err(""))?; //! # let bob_their_secret_shares = bob_state.their_secret_shares().or(Err(""))?; //! # //! # let mut carol_other_participants: Vec<Participant> = vec!(alice.clone(), bob.clone()); //! # let carol_state = DistributedKeyGeneration::<_>::new(¶ms, &carol.index, &carol_coefficients, //! # &mut carol_other_participants).or(Err(""))?; //! # let carol_their_secret_shares = carol_state.their_secret_shares().or(Err(""))?; //! # let alice_my_secret_shares = vec!(bob_their_secret_shares[0].clone(), //! # carol_their_secret_shares[0].clone()); //! # let bob_my_secret_shares = vec!(alice_their_secret_shares[0].clone(), //! # carol_their_secret_shares[1].clone()); //! # let carol_my_secret_shares = vec!(alice_their_secret_shares[1].clone(), //! # bob_their_secret_shares[1].clone()); //! # //! # let alice_state = alice_state.to_round_two(alice_my_secret_shares).or(Err(""))?; //! # let bob_state = bob_state.to_round_two(bob_my_secret_shares).or(Err(""))?; //! # let carol_state = carol_state.to_round_two(carol_my_secret_shares).or(Err(""))?; //! # //! # let (alice_group_key, alice_secret_key) = alice_state.finish(alice.public_key().unwrap()).or(Err(""))?; //! # let (bob_group_key, bob_secret_key) = bob_state.finish(bob.public_key().unwrap()).or(Err(""))?; //! # let (carol_group_key, carol_secret_key) = carol_state.finish(carol.public_key().unwrap()).or(Err(""))?; //! # //! # let alice_public_key = alice_secret_key.to_public(); //! # let bob_public_key = bob_secret_key.to_public(); //! # let carol_public_key = carol_secret_key.to_public(); //! # //! # let (alice_public_comshares, mut alice_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 1, 1); //! # let (bob_public_comshares, mut bob_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 2, 1); //! # let (carol_public_comshares, mut carol_secret_comshares) = generate_commitment_share_lists(&mut OsRng, 3, 1); //! # //! # let context = b"CONTEXT STRING STOLEN FROM DALEK TEST SUITE"; //! # let message = b"This is a test of the tsunami alert system. This is only a test."; //! # //! # let message_hash = compute_message_hash(&context[..], &message[..]); //! # //! # let mut aggregator = SignatureAggregator::new(params, bob_group_key.clone(), &context[..], &message[..]); //! # //! # aggregator.include_signer(1, alice_public_comshares.commitments[0], (&alice_secret_key).into()); //! # aggregator.include_signer(3, carol_public_comshares.commitments[0], (&carol_secret_key).into()); //! # //! # let signers = aggregator.get_signers(); //! //! let alice_partial = alice_secret_key.sign(&message_hash, &alice_group_key, //! &mut alice_secret_comshares, 0, signers)?; //! let carol_partial = carol_secret_key.sign(&message_hash, &carol_group_key, //! &mut carol_secret_comshares, 0, signers)?; //! //! aggregator.include_partial_signature(alice_partial); //! aggregator.include_partial_signature(carol_partial); //! # Ok(()) } //! # #[cfg(feature = "std")] //! # fn main() { assert!(do_test().is_ok()); } //! # #[cfg(not(feature = "std"))] //! # fn main() { } //! ``` //! //! ## Signature Aggregation //! //! Once all the expected signers have sent their partial signatures, the //! aggregator attempts to finalize its state, ensuring that there are no errors //! thus far in the partial signatures, before finally attempting to complete //! the aggregation of the partial signatures into a threshold signature. //! //! ```rust,ignore //! let aggregator = aggregator.finalize()?; //! ``` //! //! If the aggregator could not finalize the state, then the `.finalize()` method //! will return a `HashMap<u32, &'static str>` describing participant indices and the issues //! encountered for them. These issues are **guaranteed to be the fault of the aggregator**, //! e.g. not collecting all the expected partial signatures, accepting two partial //! signatures from the same participant, etc. //! //! And the same for the actual aggregation, if there was an error then a //! `HashMap<u32, &'static str>` will be returned which maps participant indices to issues. //! Unlike before, however, these issues are guaranteed to be the fault of the //! corresponding participant, specifically, that their partial signature was invalid. //! //! ```rust,ignore //! let threshold_signature = aggregator.aggregate()?; //! ``` //! //! Anyone with the group public key can then verify the threshold signature //! in the same way they would for a standard Schnorr signature. //! //! ```rust,ignore //! let verified = threshold_signature.verify(&alice_group_key, &message_hash)?; //! ``` //! //! # Note on `no_std` usage //! //! Most of this crate is `no_std` compliant, however, the current //! implementation uses `HashMap`s for the signature creation and aggregation //! protocols, and thus requires the standard library. #![no_std] #![warn(future_incompatible)] #![deny(missing_docs)] #![allow(non_snake_case)] #[cfg(not(any(feature = "std", feature = "alloc")))] compile_error!("Either feature \"std\" or \"alloc\" must be enabled for this crate."); // We use the vec! macro in unittests. #[cfg(any(test, feature = "std"))] #[macro_use] extern crate std; #[cfg(feature = "alloc")] extern crate alloc; pub mod keygen; pub mod parameters; pub mod precomputation; pub mod nizk; // The signing protocol uses Hashmap (currently for both the signature aggregator // and signers), which requires std. #[cfg(feature = "std")] pub mod signature; pub use keygen::DistributedKeyGeneration; pub use keygen::GroupKey; pub use keygen::IndividualPublicKey; pub use keygen::Participant; pub use keygen::SecretKey as IndividualSecretKey; pub use parameters::Parameters; pub use precomputation::generate_commitment_share_lists; #[cfg(feature = "std")] pub use signature::compute_message_hash; #[cfg(feature = "std")] pub use signature::SignatureAggregator;