Nullifier map optimization (#349)

* nullifier map optimization

* changelog

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased]
 ### Added
+- [\#349](https://github.com/Manta-Network/manta-rs/pull/349) Nullifier map optimization.
 - [\#345](https://github.com/Manta-Network/manta-rs/pull/345) Precompute ledger and minor bug fix.
 
 ### Changed

manta-accounting/src/transfer/mod.rs

@@ -169,7 +169,8 @@ pub trait Configuration {
             Secret = Self::SpendSecret,
             Nullifier = Self::Nullifier,
             Identifier = Self::Identifier,
-        > + utxo::UtxoReconstruct;
+        > + utxo::NullifierOpen
+        + utxo::UtxoReconstruct;
 
     /// Authorization Context Variable Type
     type AuthorizationContextVar: Variable<

manta-accounting/src/transfer/utxo/mod.rs

@@ -91,6 +91,26 @@ impl IndependenceContext for NullifierIndependence {
     const DEFAULT: bool = false;
 }
 
+/// Nullifier Open
+pub trait NullifierOpen: AssetType + DeriveDecryptionKey + NullifierType {
+    /// Opens the outgoing note in `nullifier` with `decryption_key`.
+    fn open(
+        &self,
+        nullifier: &Self::Nullifier,
+        decryption_key: &Self::DecryptionKey,
+    ) -> Option<Self::Asset>;
+
+    /// Returns `true` if `nullifier` can be opened with `decryption_key`.
+    #[inline]
+    fn can_be_opened(
+        &self,
+        nullifier: &Self::Nullifier,
+        decryption_key: &Self::DecryptionKey,
+    ) -> bool {
+        self.open(nullifier, decryption_key).is_some()
+    }
+}
+
 /// Identifier
 pub trait IdentifierType {
     /// Identifier Type

manta-accounting/src/transfer/utxo/protocol.rs

@@ -1368,6 +1368,31 @@ where
     }
 }
 
+impl<C> utxo::NullifierOpen for Parameters<C>
+where
+    C: Configuration<Bool = bool>,
+    C::OutgoingBaseEncryptionScheme:
+        Decrypt<DecryptionKey = C::Group, DecryptedPlaintext = Option<Asset<C>>>,
+{
+    #[inline]
+    fn open(
+        &self,
+        nullifier: &Self::Nullifier,
+        decryption_key: &Self::DecryptionKey,
+    ) -> Option<Self::Asset> {
+        Hybrid::new(
+            StandardDiffieHellman::new(self.base.group_generator.generator().clone()),
+            self.base.outgoing_base_encryption_scheme.clone(),
+        )
+        .decrypt(
+            decryption_key,
+            &C::OutgoingHeader::default(),
+            &nullifier.outgoing_note.ciphertext,
+            &mut (),
+        )
+    }
+}
+
 impl<C> utxo::NoteOpen for Parameters<C>
 where
     C: Configuration<Bool = bool>,

manta-accounting/src/wallet/signer/functions.rs

@@ -29,8 +29,8 @@ use crate::{
         receiver::ReceiverPost,
         requires_authorization,
         utxo::{
-            auth::DeriveContext, DeriveAddress as _, DeriveDecryptionKey, DeriveSpend, Spend,
-            UtxoReconstruct,
+            auth::DeriveContext, DeriveAddress as _, DeriveDecryptionKey, DeriveSpend,
+            NullifierOpen, Spend, UtxoReconstruct,
         },
         Address, Asset, AssociatedData, Authorization, AuthorizationContext, FullParametersRef,
         IdentifiedAsset, Identifier, IdentityProof, Note, Nullifier, Parameters, PreSender,
@@ -162,7 +162,7 @@ fn insert_next_item<C>(
         asset.clone(),
         rng,
     );
-    if nullifiers.contains_item(&nullifier) {
+    if nullifiers.remove(&nullifier) {
         utxo_accumulator.insert_nonprovable(&item_hash::<C>(parameters, &utxo));
     } else {
         utxo_accumulator.insert(&item_hash::<C>(parameters, &utxo));
@@ -192,7 +192,7 @@ where
 {
     let (_, utxo, nullifier) =
         parameters.derive_spend(authorization_context, identifier, asset.clone(), rng);
-    if nullifiers.contains_item(&nullifier) {
+    if nullifiers.remove(&nullifier) {
         utxo_accumulator.remove_proof(&item_hash::<C>(parameters, &utxo));
         if !asset.is_zero() {
             withdraw.push(asset);
@@ -224,10 +224,14 @@ where
     C::AssetValue: CheckedAdd<Output = C::AssetValue> + CheckedSub<Output = C::AssetValue>,
 {
     let nullifier_count = nullifier_data.len();
-    nullifiers.extend(nullifier_data);
     let mut deposit = Vec::new();
     let mut withdraw = Vec::new();
     let decryption_key = parameters.derive_decryption_key(authorization_context);
+    nullifiers.extend(
+        nullifier_data
+            .into_iter()
+            .filter(|nullifier| parameters.can_be_opened(nullifier, &decryption_key)),
+    );
     let mut nonprovable_inserts = Vec::new();
     for (utxo, note) in inserts {
         if let Some((identifier, asset)) = parameters.open_with_check(&decryption_key, &utxo, note)

manta-accounting/src/wallet/signer/nullifier_map.rs

@@ -43,6 +43,9 @@ pub trait NullifierMap<T>: Default {
     where
         I: IntoIterator<Item = T>;
 
+    /// Removes `item` from `self`.
+    fn remove(&mut self, item: &T) -> bool;
+
     /// Checks if `self` contains `item`.
     fn contains_item(&self, item: &T) -> bool;
 }
@@ -75,6 +78,16 @@ where
         Extend::extend(self, items)
     }
 
+    #[inline]
+    fn remove(&mut self, item: &T) -> bool {
+        if let Some(index) = self.iter().position(|x| x == item) {
+            self.remove(index);
+            true
+        } else {
+            false
+        }
+    }
+
     #[inline]
     fn contains_item(&self, item: &T) -> bool {
         self.contains(item)
@@ -108,6 +121,11 @@ where
         Extend::extend(self, items)
     }
 
+    #[inline]
+    fn remove(&mut self, item: &T) -> bool {
+        self.remove(item)
+    }
+
     #[inline]
     fn contains_item(&self, item: &T) -> bool {
         self.contains(item)
@@ -142,6 +160,11 @@ where
         Extend::extend(self, items)
     }
 
+    #[inline]
+    fn remove(&mut self, item: &T) -> bool {
+        self.remove(item)
+    }
+
     #[inline]
     fn contains_item(&self, item: &T) -> bool {
         self.contains(item)

manta-pay/src/lib.rs

@@ -33,8 +33,8 @@ pub mod config;
 #[cfg_attr(doc_cfg, doc(cfg(feature = "key")))]
 pub mod key;
 
-#[cfg(all(feature = "parameters"))]
-#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parameters"))))]
+#[cfg(feature = "parameters")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parameters")))]
 pub mod parameters;
 
 #[cfg(feature = "groth16")]