sequencer/
state_cert.rs

1//! State certificate validation and error handling
2
3use std::collections::HashMap;
4
5use alloy::primitives::{FixedBytes, U256};
6use anyhow::bail;
7use espresso_types::SeqTypes;
8use hotshot_query_service::availability::Error;
9use hotshot_task_impls::helpers::derive_signed_state_digest;
10use hotshot_types::{
11    light_client::StateVerKey,
12    simple_certificate::LightClientStateUpdateCertificateV2,
13    stake_table::HSStakeTable,
14    traits::signature_key::{LCV2StateSignatureKey, LCV3StateSignatureKey, StakeTableEntryType},
15};
16use tide_disco::StatusCode;
17
18/// Error type for state certificate fetching
19#[derive(Debug, thiserror::Error)]
20pub enum StateCertFetchError {
21    #[error("Failed to fetch state certificate: {0}")]
22    FetchError(#[source] anyhow::Error),
23
24    #[error("State certificate validation failed: {0}")]
25    ValidationError(#[source] anyhow::Error),
26
27    #[error("State certificate error: {0}")]
28    Other(#[source] anyhow::Error),
29}
30
31impl From<StateCertFetchError> for hotshot_query_service::availability::Error {
32    fn from(err: StateCertFetchError) -> Self {
33        match err {
34            StateCertFetchError::FetchError(e) => Error::Custom {
35                message: format!("Failed to fetch state cert from peers: {e}"),
36                status: StatusCode::NOT_FOUND,
37            },
38            StateCertFetchError::ValidationError(e) => Error::Custom {
39                message: format!("State certificate validation failed: {e}"),
40                status: StatusCode::INTERNAL_SERVER_ERROR,
41            },
42            StateCertFetchError::Other(e) => Error::Custom {
43                message: format!("Failed to process state cert: {e}"),
44                status: StatusCode::INTERNAL_SERVER_ERROR,
45            },
46        }
47    }
48}
49
50/// Validates a state certificate by verifying signatures and checking threshold
51pub fn validate_state_cert(
52    cert: &LightClientStateUpdateCertificateV2<SeqTypes>,
53    stake_table: &HSStakeTable<SeqTypes>,
54) -> anyhow::Result<()> {
55    let signed_state_digest = derive_signed_state_digest(
56        &cert.light_client_state,
57        &cert.next_stake_table_state,
58        &cert.auth_root,
59    );
60
61    // If auth_root is the default value (all zeros), we're on consensus version V3, so verify LCV2 signatures only
62    // For consensus >= V4, verify both LCV3 and LCV2 signatures
63    let use_lcv2_only = cert.auth_root == FixedBytes::<32>::default();
64
65    let signature_map: HashMap<&StateVerKey, _> = cert
66        .signatures
67        .iter()
68        .map(|(key, lcv3_sig, lcv2_sig)| (key, (lcv3_sig, lcv2_sig)))
69        .collect();
70
71    // Verify signatures and accumulate weight
72    let mut accumulated_weight = U256::ZERO;
73
74    for peer in stake_table.iter() {
75        if let Some((lcv3_sig, lcv2_sig)) = signature_map.get(&peer.state_ver_key) {
76            let lcv2_valid = <StateVerKey as LCV2StateSignatureKey>::verify_state_sig(
77                &peer.state_ver_key,
78                lcv2_sig,
79                &cert.light_client_state,
80                &cert.next_stake_table_state,
81            );
82
83            let is_valid = if use_lcv2_only {
84                lcv2_valid
85            } else {
86                let lcv3_valid = <StateVerKey as LCV3StateSignatureKey>::verify_state_sig(
87                    &peer.state_ver_key,
88                    lcv3_sig,
89                    signed_state_digest,
90                );
91
92                lcv3_valid && lcv2_valid
93            };
94
95            if is_valid {
96                accumulated_weight += peer.stake_table_entry.stake();
97            } else {
98                bail!(format!(
99                    "Invalid signature from key: {}",
100                    peer.state_ver_key
101                ))
102            }
103        }
104    }
105
106    // Check if accumulated weight meets the threshold
107    let total_stake = stake_table.total_stakes();
108    let threshold = hotshot_types::stake_table::one_honest_threshold(total_stake);
109    if accumulated_weight < threshold {
110        bail!(
111            "State certificate validation failed: accumulated weight {accumulated_weight} is \
112             below threshold {threshold}",
113        );
114    }
115
116    Ok(())
117}
sequencer/state_cert.rs

sequencer/
state_cert.rs
