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a few more october comments
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Hannah Davis committed Dec 12, 2024
1 parent 67dc551 commit 0db277e
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Showing 4 changed files with 64 additions and 92 deletions.
3 changes: 1 addition & 2 deletions src/bt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,7 @@
//! tree.insert(bits!(1, 1), 'f');
// TODO(#947): Remove these lines once the module gets used by Mastic implementation.
#[allow(dead_code)]

#![allow(dead_code)]
use core::fmt::Debug;
use std::io::Cursor;

Expand Down
48 changes: 23 additions & 25 deletions src/flp/szk.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -253,13 +253,13 @@ impl<F: FieldElement + Decode, const SEED_SIZE: usize> ParameterizedDecode<(bool
/// Szk query state.
///
/// The state that needs to be stored by an Szk verifier between query() and decide().
pub type SzkQueryState<const SEED_SIZE: usize> = Option<Seed<SEED_SIZE>>;
pub(crate) type SzkQueryState<const SEED_SIZE: usize> = Option<Seed<SEED_SIZE>>;

/// Joint share type for the SZK proof.
///
/// This is produced as the result of combining two query shares.
/// It contains the re-computed joint randomness seed, if applicable. It is consumed by [`Szk::decide`].
pub type SzkJointShare<const SEED_SIZE: usize> = Option<Seed<SEED_SIZE>>;
pub(crate) type SzkJointShare<const SEED_SIZE: usize> = Option<Seed<SEED_SIZE>>;

impl<const SEED_SIZE: usize> Encode for SzkJointShare<SEED_SIZE> {
fn encode(&self, bytes: &mut Vec<u8>) -> Result<(), CodecError> {
Expand Down Expand Up @@ -492,7 +492,7 @@ where
pub(crate) fn query(
&self,
input_share: &[T::Field],
proof_share: SzkProofShare<T::Field, SEED_SIZE>,
proof_share: &SzkProofShare<T::Field, SEED_SIZE>,
verify_key: &[u8; SEED_SIZE],
nonce: &[u8; 16],
) -> Result<(SzkQueryShare<T::Field, SEED_SIZE>, SzkQueryState<SEED_SIZE>), SzkError> {
Expand All @@ -515,11 +515,11 @@ where
leader_blind_and_helper_joint_rand_part_opt,
} => match leader_blind_and_helper_joint_rand_part_opt {
Some((seed, helper_joint_rand_part)) => {
match self.derive_joint_rand_part(&seed, input_share, nonce) {
match self.derive_joint_rand_part(seed, input_share, nonce) {
Ok(leader_joint_rand_part) => (
self.derive_joint_rand_and_seed(
&leader_joint_rand_part,
&helper_joint_rand_part,
helper_joint_rand_part,
),
leader_joint_rand_part,
),
Expand All @@ -537,13 +537,13 @@ where
leader_joint_rand_part_opt,
} => match leader_joint_rand_part_opt {
Some(leader_joint_rand_part) => match self.derive_joint_rand_part(
&proof_share_seed_and_blind,
proof_share_seed_and_blind,
input_share,
nonce,
) {
Ok(helper_joint_rand_part) => (
self.derive_joint_rand_and_seed(
&leader_joint_rand_part,
leader_joint_rand_part,
&helper_joint_rand_part,
),
helper_joint_rand_part,
Expand Down Expand Up @@ -581,7 +581,7 @@ where
))
}

pub(crate) fn merge_verifiers(
pub(crate) fn merge_query_shares(
&self,
mut leader_share: SzkQueryShare<T::Field, SEED_SIZE>,
helper_share: SzkQueryShare<T::Field, SEED_SIZE>,
Expand Down Expand Up @@ -610,9 +610,10 @@ where
Err(SzkError::Decide("failed to verify FLP proof".to_string()))
}
}
/// Returns true if the leader and helper derive identical joint randomness
/// seeds
pub fn decide(

/// Returns true if the joint randomness seed used during the query phase
/// was correctly computed from both aggregators' parts.
pub(crate) fn decide(
&self,
query_state: SzkQueryState<SEED_SIZE>,
joint_share: SzkJointShare<SEED_SIZE>,
Expand Down Expand Up @@ -711,19 +712,14 @@ mod tests {

let [l_proof_share, h_proof_share] = proof_shares.unwrap();
let (l_query_share, l_query_state) = szk_typ
.query(
&leader_input_share,
l_proof_share.clone(),
&verify_key,
&nonce,
)
.query(&leader_input_share, &l_proof_share, &verify_key, &nonce)
.unwrap();
let (h_query_share, h_query_state) = szk_typ
.query(&helper_input_share, h_proof_share, &verify_key, &nonce)
.query(&helper_input_share, &h_proof_share, &verify_key, &nonce)
.unwrap();

let joint_share_result =
szk_typ.merge_verifiers(l_query_share.clone(), h_query_share.clone());
szk_typ.merge_query_shares(l_query_share.clone(), h_query_share.clone());
let joint_share = match joint_share_result {
Ok(joint_share) => {
let leader_decision = szk_typ
Expand Down Expand Up @@ -764,7 +760,8 @@ mod tests {
);
}

let joint_share_res = szk_typ.merge_verifiers(mutated_query_share, h_query_share.clone());
let joint_share_res =
szk_typ.merge_query_shares(mutated_query_share, h_query_share.clone());
let leader_decision = match joint_share_res {
Ok(joint_share) => szk_typ.decide(l_query_state.clone(), joint_share).is_ok(),
Err(_) => false,
Expand All @@ -776,10 +773,11 @@ mod tests {
mutated_input[0] *=
T::Field::from(<T::Field as FieldElementWithInteger>::Integer::try_from(23).unwrap());
let (mutated_query_share, mutated_query_state) = szk_typ
.query(&mutated_input, l_proof_share.clone(), &verify_key, &nonce)
.query(&mutated_input, &l_proof_share, &verify_key, &nonce)
.unwrap();

let joint_share_res = szk_typ.merge_verifiers(mutated_query_share, h_query_share.clone());
let joint_share_res =
szk_typ.merge_query_shares(mutated_query_share, h_query_share.clone());

let leader_decision = match joint_share_res {
Ok(joint_share) => szk_typ.decide(mutated_query_state, joint_share).is_ok(),
Expand All @@ -793,7 +791,7 @@ mod tests {
uncompressed_proof_share,
leader_blind_and_helper_joint_rand_part_opt,
} => (
uncompressed_proof_share.clone(),
uncompressed_proof_share,
leader_blind_and_helper_joint_rand_part_opt,
),
_ => (vec![], None),
Expand All @@ -807,12 +805,12 @@ mod tests {
let (l_query_share, l_query_state) = szk_typ
.query(
&leader_input_share,
mutated_proof_share,
&mutated_proof_share,
&verify_key,
&nonce,
)
.unwrap();
let joint_share_res = szk_typ.merge_verifiers(l_query_share, h_query_share.clone());
let joint_share_res = szk_typ.merge_query_shares(l_query_share, h_query_share.clone());

let leader_decision = match joint_share_res {
Ok(joint_share) => szk_typ.decide(l_query_state.clone(), joint_share).is_ok(),
Expand Down
87 changes: 36 additions & 51 deletions src/vdaf/mastic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
//! [draft-mouris-cfrg-mastic-01]: https://www.ietf.org/archive/id/draft-mouris-cfrg-mastic-01.html
use crate::{
bt::{BinaryTree, Path},
bt::BinaryTree,
codec::{CodecError, Decode, Encode, ParameterizedDecode},
field::{decode_fieldvec, FieldElement},
flp::{
Expand Down Expand Up @@ -282,7 +282,6 @@ where
2
}
}

impl<T, P, const SEED_SIZE: usize> Mastic<T, P, SEED_SIZE>
where
T: Type,
Expand Down Expand Up @@ -531,14 +530,6 @@ where
self.vidpf.weight_parameter * agg_param.level_and_prefixes.prefixes().len(),
);
let mut cache_tree = BinaryTree::<VidpfEvalCache<VidpfWeight<T::Field>>>::default();
let cache = VidpfEvalCache::<VidpfWeight<T::Field>>::init_from_key(
id,
&input_share.vidpf_key,
&self.vidpf.weight_parameter,
);
cache_tree
.insert(Path::empty(), cache)
.expect("Should alwys be able to insert into empty tree at root");
for prefix in agg_param.level_and_prefixes.prefixes() {
let mut value_share = self.vidpf.eval_with_cache(
id,
Expand All @@ -552,52 +543,46 @@ where
output_shares.append(&mut value_share.share.0);
}

let szk_verify_opt = if agg_param.require_weight_check {
let root_share = self.vidpf.eval_root_with_cache(
Ok(if agg_param.require_weight_check {
let MasticInputShare {
vidpf_key,
proof_share,
} = input_share;
let root_share = self.vidpf.get_root_weight_share(
id,
&input_share.vidpf_key,
vidpf_key,
public_share,
&mut cache_tree,
nonce,
)?;
Some(self.szk.query(
root_share.as_ref(),
input_share.proof_share.clone(),
verify_key,
nonce,
)?)
let (szk_query_share, szk_query_state) =
self.szk
.query(root_share.as_ref(), proof_share, verify_key, nonce)?;
let verifier_len = szk_query_share.flp_verifier.len();
(
MasticPrepareState {
output_shares: MasticOutputShare::<T::Field>::from(output_shares),
szk_query_state,
verifier_len: Some(verifier_len),
},
MasticPrepareShare {
vidpf_proof: eval_proof.into_seed(),
szk_query_share_opt: Some(szk_query_share),
},
)
} else {
None
};

let (prep_share, prep_state) =
if let Some((szk_query_share, szk_query_state)) = szk_verify_opt {
let verifier_len = szk_query_share.flp_verifier.len();
(
MasticPrepareShare {
vidpf_proof: eval_proof.into_seed(),
szk_query_share_opt: Some(szk_query_share),
},
MasticPrepareState {
output_shares: MasticOutputShare::<T::Field>::from(output_shares),
szk_query_state,
verifier_len: Some(verifier_len),
},
)
} else {
(
MasticPrepareShare {
vidpf_proof: eval_proof.into_seed(),
szk_query_share_opt: None,
},
MasticPrepareState {
output_shares: MasticOutputShare::<T::Field>::from(output_shares),
szk_query_state: None,
verifier_len: None,
},
)
};
Ok((prep_state, prep_share))
(
MasticPrepareState {
output_shares: MasticOutputShare::<T::Field>::from(output_shares),
szk_query_state: None,
verifier_len: None,
},
MasticPrepareShare {
vidpf_proof: eval_proof.into_seed(),
szk_query_share_opt: None,
},
)
})
}

fn prepare_shares_to_prepare_message<
Expand Down Expand Up @@ -631,7 +616,7 @@ where
) {
(Some(leader_query_share), Some(helper_query_share)) => Ok(self
.szk
.merge_verifiers(leader_query_share, helper_query_share)?),
.merge_query_shares(leader_query_share, helper_query_share)?),
(None, None) => Ok(None),
(_, _) => Err(VdafError::Uncategorized(
"Only one of leader and helper query shares is present".to_string(),
Expand Down
18 changes: 4 additions & 14 deletions src/vidpf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -326,7 +326,7 @@ impl<W: VidpfValue, const NONCE_SIZE: usize> Vidpf<W, NONCE_SIZE> {
Ok((next_state, y))
}

pub(crate) fn eval_root_with_cache(
pub(crate) fn get_root_weight_share(
&self,
id: VidpfServerId,
key: &VidpfKey,
Expand Down Expand Up @@ -470,7 +470,7 @@ impl VidpfDomainSepTag {
/// Vidpf key.
///
/// Private key of an aggregation server.
pub type VidpfKey = Seed<16>;
pub type VidpfKey = Seed<VIDPF_SEED_SIZE>;

/// Vidpf server ID.
///
Expand Down Expand Up @@ -634,17 +634,6 @@ pub struct VidpfEvalCache<W: VidpfValue> {
}

impl<W: VidpfValue> VidpfEvalCache<W> {
pub(crate) fn init_from_key(
id: VidpfServerId,
key: &VidpfKey,
length: &W::ValueParameter,
) -> Self {
Self {
state: VidpfEvalState::init_from_key(id, key),
share: W::zero(length),
}
}

fn to_share(&self) -> VidpfValueShare<W> {
VidpfValueShare::<W> {
share: self.share.clone(),
Expand All @@ -663,6 +652,7 @@ pub struct VidpfValueShare<W: VidpfValue> {

/// Proof size in bytes.
const VIDPF_PROOF_SIZE: usize = 32;
const VIDPF_SEED_SIZE: usize = 16;

/// Allows to validate user input and shares after evaluation.
type VidpfProof = [u8; VIDPF_PROOF_SIZE];
Expand All @@ -678,7 +668,7 @@ fn conditional_xor_proof(mut lhs: VidpfProof, rhs: &VidpfProof, choice: Choice)
}

/// Feeds a pseudorandom generator during evaluation.
type VidpfSeed = [u8; 16];
type VidpfSeed = [u8; VIDPF_SEED_SIZE];

/// Contains the seeds and control bits produced by [`Vidpf::prg`].
struct VidpfPrgOutput {
Expand Down

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