hotshot_types/traits/
qc.rs

1// Copyright (c) 2021-2024 Espresso Systems (espressosys.com)
2// This file is part of the HotShot repository.
3
4// You should have received a copy of the MIT License
5// along with the HotShot repository. If not, see <https://mit-license.org/>.
6
7//! The quorum certificate (QC) trait is a certificate of a sufficient quorum of distinct
8//! parties voted for a message or statement.
9
10use ark_std::{
11    rand::{CryptoRng, RngCore},
12    vec::Vec,
13};
14use bitvec::prelude::*;
15use digest::generic_array::{ArrayLength, GenericArray};
16use jf_signature::{AggregateableSignatureSchemes, SignatureError};
17
18/// Trait for validating a QC built from different signatures on the same message
19pub trait QuorumCertificateScheme<A: AggregateableSignatureSchemes> {
20    /// Public parameters for generating the QC
21    /// E.g: snark proving/verifying keys, list of (or pointer to) public keys stored in the smart contract.
22    type QcProverParams<'a>;
23
24    /// Public parameters for validating the QC
25    /// E.g: verifying keys, stake table commitment
26    type QcVerifierParams<'a>;
27
28    /// Allows to fix the size of the message at compilation time.
29    type MessageLength: ArrayLength<A::MessageUnit>;
30
31    /// Type of the actual quorum certificate object
32    type Qc;
33
34    /// Type of the quorum size (e.g. number of votes or accumulated weight of signatures)
35    type QuorumSize;
36
37    /// Produces a partial signature on a message with a single user signing key
38    /// NOTE: the original message (vote) should be prefixed with the hash of the stake table.
39    /// * `agg_sig_pp` - public parameters for aggregate signature
40    /// * `message` - message to be signed
41    /// * `sk` - user signing key
42    /// * `returns` - a "simple" signature
43    ///
44    /// # Errors
45    ///
46    /// Should return error if the underlying signature scheme fail to sign.
47    fn sign<R: CryptoRng + RngCore, M: AsRef<[A::MessageUnit]>>(
48        pp: &A::PublicParameter,
49        sk: &A::SigningKey,
50        msg: M,
51        prng: &mut R,
52    ) -> Result<A::Signature, SignatureError> {
53        A::sign(pp, sk, msg, prng)
54    }
55
56    /// Computes an aggregated signature from a set of partial signatures and the verification keys involved
57    /// * `qc_pp` - public parameters for generating the QC
58    /// * `signers` - a bool vector indicating the list of verification keys corresponding to the set of partial signatures
59    /// * `sigs` - partial signatures on the same message
60    ///
61    /// # Errors
62    ///
63    /// Will return error if some of the partial signatures provided are invalid or the number of
64    /// partial signatures / verifications keys are different.
65    fn assemble(
66        qc_pp: &Self::QcProverParams<'_>,
67        signers: &BitSlice,
68        sigs: &[A::Signature],
69    ) -> Result<Self::Qc, SignatureError>;
70
71    /// Checks an aggregated signature over some message provided as input
72    /// * `qc_vp` - public parameters for validating the QC
73    /// * `message` - message to check the aggregated signature against
74    /// * `qc` - quorum certificate
75    /// * `returns` - the quorum size if the qc is valid, an error otherwise.
76    ///
77    /// # Errors
78    ///
79    /// Return error if the QC is invalid, either because accumulated weight didn't exceed threshold,
80    /// or some partial signatures are invalid.
81    fn check(
82        qc_vp: &Self::QcVerifierParams<'_>,
83        message: &GenericArray<A::MessageUnit, Self::MessageLength>,
84        qc: &Self::Qc,
85    ) -> Result<Self::QuorumSize, SignatureError>;
86
87    /// Trace the list of signers given a qc.
88    ///
89    /// # Errors
90    ///
91    /// Return error if the inputs mismatch (e.g. wrong verifier parameter or original message).
92    fn trace(
93        qc_vp: &Self::QcVerifierParams<'_>,
94        message: &GenericArray<A::MessageUnit, Self::MessageLength>,
95        qc: &Self::Qc,
96    ) -> Result<Vec<A::VerificationKey>, SignatureError>;
97}
hotshot_types/traits/qc.rs

hotshot_types/traits/
qc.rs
