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/*
* AquaVM Workflow Engine
*
* Copyright (C) 2024 Fluence DAO
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
pub use super::errors::DataVerifierError;
use crate::CanonResult;
use crate::CidInfo;
use crate::ExecutedState;
use crate::ExecutionTrace;
use crate::InterpreterData;
use air_interpreter_cid::{CidRef, CID};
use air_interpreter_signatures::PublicKey;
use air_interpreter_signatures::Signature;
use air_interpreter_signatures::SignatureStore;
use std::collections::HashMap;
use std::rc::Rc;
const CANNOT_HAPPEN_IN_VERIFIED_CID_STORE: &str = "cannot happen in a checked CID store";
/// An util for verificating particular data's signatures.
pub struct DataVerifier<'data> {
// a map from peer_id to peer's info (public key, signature, CIDS)
grouped_cids: HashMap<Box<str>, PeerInfo<'data>>,
salt: &'data str,
}
impl<'data> DataVerifier<'data> {
// it can be further optimized if only required parts are passed;
// SignatureStore is not used elsewhere
pub fn new(data: &'data InterpreterData, salt: &'data str) -> Result<Self, DataVerifierError> {
// validate key algoritms
for (public_key, _) in data.signatures.iter() {
public_key
.validate()
.map_err(|error| DataVerifierError::MalformedKey {
error,
key: public_key.to_string(),
})?;
}
// it contains signature too; if we try to add a value to a peer w/o signature, it is an immediate error
let mut grouped_cids: HashMap<Box<str>, PeerInfo<'data>> = data
.signatures
.iter()
.map(|(public_key, signature)| {
(
public_key
.to_peer_id()
.expect("cannot happen, was verifeid before")
.to_string()
.into(),
PeerInfo::new(public_key, signature),
)
})
.collect();
// fill PeerInfo's `cids` field, checking for peer IDs without a key
collect_peers_cids_from_trace(&data.trace, &data.cid_info, &mut grouped_cids)?;
// sort cids for canonicalization
for peer_info in grouped_cids.values_mut() {
peer_info.cids.sort_unstable();
}
Ok(Self { grouped_cids, salt })
}
/// Verify each peers' signatures.
pub fn verify(&self) -> Result<(), DataVerifierError> {
for peer_info in self.grouped_cids.values() {
peer_info
.public_key
.verify(&peer_info.cids, self.salt, peer_info.signature)
.map_err(|error| DataVerifierError::SignatureMismatch {
error: error.into(),
cids: peer_info.cids.clone(),
peer_id: peer_info
.public_key
.to_peer_id()
.expect("cannot happen, was verified before")
.to_string(),
})?;
}
Ok(())
}
/// For each peer, merge previous and current CID multisets by determining the largest set.
///
/// This code uses an invariant: peer's multiset of produced CIDs is always a superset of
/// previous invocation's multiset:
///
/// A_0 ⊆ A_1 ⊆ ... ⊆ A_n.
///
/// So, the largest multiset is selected as the result of merging, the invariant is checked,
/// and a error is returned if it is violated.
///
/// If the multisets are of same size, they have to be equal.
// TODO enforce merging only verified sets
// The result is same regardless argument order, so "prevous/current" terminology
// is not used deliberately.
pub fn merge(mut self, other: Self) -> Result<SignatureStore, DataVerifierError> {
use std::collections::hash_map::Entry::*;
for (other_peer_pk, mut other_info) in other.grouped_cids {
let our_info = self.grouped_cids.entry(other_peer_pk);
match our_info {
Occupied(mut our_info_ent) => {
debug_assert_eq!(other_info.public_key, our_info_ent.get().public_key);
if our_info_ent.get().cids.len() < other_info.cids.len() {
// the merged map contains the largest set for each peer_id
//
// this code assumes that a peer only adds CIDs to its set, so CID multisets
// are growing-only; but it is additionally checked below
// so, we get a largest set as merged one
std::mem::swap(our_info_ent.get_mut(), &mut other_info);
}
// nb: if length are equal, sets should be equal, and any of them
// should be used; if they are not equal, check_cid_multiset_consistency
// will detect it.
let larger_info = our_info_ent.get();
let smaller_info = &other_info;
check_cid_multiset_invariant(larger_info, smaller_info)?;
}
Vacant(ent) => {
ent.insert(other_info);
}
}
}
let mut store = SignatureStore::new();
for peer_info in self.grouped_cids.into_values() {
store.put(peer_info.public_key.clone(), peer_info.signature.clone())
}
Ok(store)
}
}
fn collect_peers_cids_from_trace<'data>(
trace: &'data ExecutionTrace,
cid_info: &'data CidInfo,
grouped_cids: &mut HashMap<Box<str>, PeerInfo<'data>>,
) -> Result<(), DataVerifierError> {
for elt in trace {
match elt {
ExecutedState::Call(ref call) => {
let cid = call.get_cid();
if let Some(cid) = cid {
// TODO refactor
let service_result = cid_info
.service_result_store
.get(cid)
.expect(CANNOT_HAPPEN_IN_VERIFIED_CID_STORE);
let tetraplet = cid_info
.tetraplet_store
.get(&service_result.tetraplet_cid)
.expect(CANNOT_HAPPEN_IN_VERIFIED_CID_STORE);
let peer_pk = tetraplet.peer_pk.as_str();
try_push_cid(grouped_cids, peer_pk, cid)?;
}
}
ExecutedState::Canon(CanonResult::Executed(ref cid)) => {
// TODO refactor
let canon_result = cid_info
.canon_result_store
.get(cid)
.expect(CANNOT_HAPPEN_IN_VERIFIED_CID_STORE);
let tetraplet = cid_info
.tetraplet_store
.get(&canon_result.tetraplet)
.expect(CANNOT_HAPPEN_IN_VERIFIED_CID_STORE);
let peer_pk = tetraplet.peer_pk.as_str();
try_push_cid(grouped_cids, peer_pk, cid)?;
}
_ => {}
};
}
Ok(())
}
fn try_push_cid<T>(
grouped_cids: &mut HashMap<Box<str>, PeerInfo<'_>>,
peer_pk: &str,
cid: &CID<T>,
) -> Result<(), DataVerifierError> {
match grouped_cids.get_mut(peer_pk) {
Some(peer_info) => {
peer_info.cids.push(cid.get_inner());
Ok(())
}
None => Err(DataVerifierError::PeerIdNotFound(peer_pk.into())),
}
}
/// Safety check for malicious peer that returns inconsistent CID multisets,
/// i.e. non-increasing multisets.
fn check_cid_multiset_invariant(
larger_pair: &PeerInfo<'_>,
smaller_pair: &PeerInfo<'_>,
) -> Result<(), DataVerifierError> {
let larger_cids = &larger_pair.cids;
let smaller_cids = &smaller_pair.cids;
let larger_count_map = to_count_map(larger_cids);
let smaller_count_map = to_count_map(smaller_cids);
if is_multisubset(larger_count_map, smaller_count_map) {
Ok(())
} else {
let peer_id = smaller_pair
.public_key
.to_peer_id()
.expect("cannot happen, was verified before")
.to_string();
Err(DataVerifierError::MergeMismatch {
peer_id,
larger_cids: larger_cids.clone(),
smaller_cids: smaller_cids.clone(),
})
}
}
fn to_count_map(cids: &Vec<Rc<CidRef>>) -> HashMap<&str, usize> {
let mut count_map = HashMap::<_, usize>::new();
for cid in cids {
// the counter can't overflow, the memory will overflow first
*count_map.entry(&**cid).or_default() += 1;
}
count_map
}
fn is_multisubset(
larger_count_set: HashMap<&str, usize>,
smaller_count_set: HashMap<&str, usize>,
) -> bool {
for (cid, &smaller_count) in &smaller_count_set {
debug_assert!(smaller_count > 0);
let larger_count = larger_count_set.get(cid).cloned().unwrap_or_default();
if larger_count < smaller_count {
return false;
}
}
true
}
struct PeerInfo<'data> {
/// A peer's public key.
public_key: &'data PublicKey,
/// A peer's signature.
signature: &'data Signature,
/// Sorted vector of CIDs that belong to the peer.
cids: Vec<Rc<CidRef>>,
}
impl<'data> PeerInfo<'data> {
fn new(public_key: &'data PublicKey, signature: &'data Signature) -> Self {
Self {
public_key,
signature,
cids: vec![],
}
}
}