openvm_continuations/static_verifier/
mod.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
use openvm_circuit::arch::PROGRAM_CACHED_TRACE_INDEX;
use openvm_native_compiler::prelude::*;
use openvm_native_recursion::{
    challenger::multi_field32::MultiField32ChallengerVariable,
    config::outer::{new_from_outer_multi_vk, OuterConfig},
    digest::DigestVariable,
    fri::TwoAdicFriPcsVariable,
    halo2::DslOperations,
    stark::StarkVerifier,
    utils::const_fri_config,
    vars::StarkProofVariable,
    witness::Witnessable,
};
use openvm_stark_backend::keygen::types::MultiStarkVerifyingKey;
use openvm_stark_sdk::{
    config::FriParameters, openvm_stark_backend::proof::Proof, p3_bn254_fr::Bn254Fr,
};

use crate::{
    verifier::{
        common::{
            assert_single_segment_vm_exit_successfully_with_connector_air_id, types::SpecialAirIds,
        },
        root::types::RootVmVerifierPvs,
        utils::compress_babybear_var_to_bn254,
    },
    RootSC,
};
/// Custom public values handler for static verifier.
/// This trait implementation defines what the public values of the
/// final EVM proof will be.
pub trait StaticVerifierPvHandler {
    /// Returns the number of public values, as [Bn254Fr] field elements.
    fn handle_public_values(
        &self,
        builder: &mut Builder<OuterConfig>,
        input: &StarkProofVariable<OuterConfig>,
        special_air_ids: &SpecialAirIds,
    ) -> usize;
}

pub struct DefaultStaticVerifierPvHandler;

impl StaticVerifierPvHandler for DefaultStaticVerifierPvHandler {
    fn handle_public_values(
        &self,
        builder: &mut Builder<OuterConfig>,
        input: &StarkProofVariable<OuterConfig>,
        special_air_ids: &SpecialAirIds,
    ) -> usize {
        let pv_air = builder.get(&input.per_air, special_air_ids.public_values_air_id);
        let public_values: Vec<_> = pv_air
            .public_values
            .vec()
            .into_iter()
            .map(|x| builder.cast_felt_to_var(x))
            .collect();
        let pvs = RootVmVerifierPvs::from_flatten(public_values);
        let exe_commit = compress_babybear_var_to_bn254(builder, pvs.exe_commit);
        let leaf_commit = compress_babybear_var_to_bn254(builder, pvs.leaf_verifier_commit);
        let num_public_values = 2 + pvs.public_values.len();
        builder.static_commit_public_value(0, exe_commit);
        builder.static_commit_public_value(1, leaf_commit);
        for (i, x) in pvs.public_values.into_iter().enumerate() {
            builder.static_commit_public_value(i + 2, x);
        }
        num_public_values
    }
}

/// Config to generate static verifier DSL operations.
pub struct StaticVerifierConfig {
    pub root_verifier_fri_params: FriParameters,
    pub special_air_ids: SpecialAirIds,
    pub root_verifier_program_commit: [Bn254Fr; 1],
}

impl StaticVerifierConfig {
    pub fn build_static_verifier_operations(
        &self,
        root_verifier_vk: &MultiStarkVerifyingKey<RootSC>,
        proof: &Proof<RootSC>,
        pv_handler: &impl StaticVerifierPvHandler,
    ) -> DslOperations<OuterConfig> {
        let mut builder = Builder::<OuterConfig>::default();
        builder.flags.static_only = true;
        let num_public_values = {
            builder.cycle_tracker_start("VerifierProgram");
            let input = proof.read(&mut builder);
            self.verify_root_proof(&mut builder, root_verifier_vk, &input);

            let num_public_values =
                pv_handler.handle_public_values(&mut builder, &input, &self.special_air_ids);
            builder.cycle_tracker_end("VerifierProgram");
            num_public_values
        };
        DslOperations {
            operations: builder.operations,
            num_public_values,
        }
    }

    /// `root_verifier_vk` is the verifying key of the root verifier STARK circuit.
    /// `root_verifier_fri_params` are the FRI parameters used to prove the root
    /// verifier STARK circuit.
    fn verify_root_proof(
        &self,
        builder: &mut Builder<OuterConfig>,
        root_verifier_vk: &MultiStarkVerifyingKey<RootSC>,
        input: &StarkProofVariable<OuterConfig>,
    ) {
        let advice = new_from_outer_multi_vk(root_verifier_vk);
        let pcs = TwoAdicFriPcsVariable {
            config: const_fri_config(builder, &self.root_verifier_fri_params),
        };
        StarkVerifier::verify::<MultiField32ChallengerVariable<_>>(builder, &pcs, &advice, input);
        {
            // Program AIR is the only AIR with a cached trace. The cached trace index doesn't
            // change after reordering.
            let t_id = RVar::from(PROGRAM_CACHED_TRACE_INDEX);
            let commit = builder.get(&input.commitments.main_trace, t_id);
            let commit = if let DigestVariable::Var(commit_arr) = commit {
                builder.get(&commit_arr, 0)
            } else {
                unreachable!()
            };
            builder.assert_var_eq(commit, self.root_verifier_program_commit[0]);
        }
        assert_single_segment_vm_exit_successfully_with_connector_air_id(
            builder,
            input,
            self.special_air_ids.connector_air_id,
        );
    }
}