Merkle Tree name refactors

crypto-primitives/src/lib.rs

@@ -6,7 +6,7 @@ extern crate derivative;
 
 pub mod commitment;
 pub mod crh;
-pub mod mht;
+pub mod merkle_tree;
 pub mod nizk;
 pub mod prf;
 pub mod signature;
@@ -14,7 +14,7 @@ pub mod signature;
 pub use self::{
     commitment::CommitmentScheme,
     crh::FixedLengthCRH,
-    mht::{HashMembershipProof, MerkleHashTree},
+    merkle_tree::{MerkleTreePath, MerkleHashTree},
     nizk::NIZK,
     prf::PRF,
     signature::SignatureScheme,
@@ -24,7 +24,7 @@ pub use self::{
 pub use self::{
     commitment::CommitmentGadget,
     crh::FixedLengthCRHGadget,
-    mht::constraints::{MerklePath, MerklePathVerifierGadget},
+    merkle_tree::constraints::MerkleTreePathGadget,
     nizk::NIZKVerifierGadget,
     prf::PRFGadget,
     signature::SigRandomizePkGadget,

crypto-primitives/src/merkle_tree/constraints.rs

@@ -3,63 +3,51 @@ use r1cs_core::{ConstraintSystem, SynthesisError};
 use r1cs_std::prelude::*;
 use r1cs_std::boolean::AllocatedBit;
 
-use crate::mht::*;
+use crate::merkle_tree::*;
 use crate::crh::{FixedLengthCRH, FixedLengthCRHGadget};
 
-use std::{borrow::Borrow, marker::PhantomData};
+use std::borrow::Borrow;
 
-pub struct MerklePath<P, HGadget, ConstraintF>
+pub struct MerkleTreePathGadget<P, HGadget, ConstraintF>
 where
-    P: MHTParameters,
+    P: MerkleTreeConfig,
     HGadget: FixedLengthCRHGadget<P::H, ConstraintF>,
     ConstraintF: Field,
 {
     path:    Vec<(HGadget::OutputGadget, HGadget::OutputGadget)>,
 }
 
-pub struct MerklePathVerifierGadget<P, CRHGadget, ConstraintF>
+impl<P, CRHGadget, ConstraintF> MerkleTreePathGadget<P, CRHGadget, ConstraintF>
 where
-    P: MHTParameters,
-    ConstraintF: Field,
-    CRHGadget: FixedLengthCRHGadget<P::H, ConstraintF>,
-{
-    _p: PhantomData<CRHGadget>,
-    _p2: PhantomData<P>,
-    _f: PhantomData<ConstraintF>,
-}
-
-impl<P, CRHGadget, ConstraintF> MerklePathVerifierGadget<P, CRHGadget, ConstraintF>
-where
-    P: MHTParameters,
+    P: MerkleTreeConfig,
     ConstraintF: Field,
     CRHGadget: FixedLengthCRHGadget<P::H, ConstraintF>,
 {
     pub fn check_membership<CS: ConstraintSystem<ConstraintF>>(
+        &self,
         cs: CS,
         parameters: &CRHGadget::ParametersGadget,
         root: &CRHGadget::OutputGadget,
         leaf: impl ToBytesGadget<ConstraintF>,
-        witness: &MerklePath<P, CRHGadget, ConstraintF>,
     ) -> Result<(), SynthesisError> {
-    Self::conditionally_check_membership(
+    self.conditionally_check_membership(
             cs,
             parameters,
             root,
             leaf,
-            witness,
             &Boolean::Constant(true),
         )
     }
 
     pub fn conditionally_check_membership<CS: ConstraintSystem<ConstraintF>>(
+        &self,
         mut cs: CS,
         parameters: &CRHGadget::ParametersGadget,
         root: &CRHGadget::OutputGadget,
         leaf: impl ToBytesGadget<ConstraintF>,
-        witness: &MerklePath<P, CRHGadget, ConstraintF>,
         should_enforce: &Boolean,
     ) -> Result<(), SynthesisError> {
-        assert_eq!(witness.path.len(), P::HEIGHT - 1);
+        assert_eq!(self.path.len(), P::HEIGHT - 1);
         // Check that the hash of the given leaf matches the leaf hash in the membership
         // proof.
         let leaf_bits = leaf.to_bytes(&mut cs.ns(|| "leaf_to_bytes"))?;
@@ -71,21 +59,21 @@ where
 
         // Check if leaf is one of the bottom-most siblings.
         let leaf_is_left = AllocatedBit::alloc(&mut cs.ns(|| "leaf_is_left"), || {
-            Ok(leaf_hash == witness.path[0].0)
+            Ok(leaf_hash == self.path[0].0)
         })?
         .into();
         CRHGadget::OutputGadget::conditional_enforce_equal_or(
             &mut cs.ns(|| "check_leaf_is_left"),
             &leaf_is_left,
             &leaf_hash,
-            &witness.path[0].0,
-            &witness.path[0].1,
+            &self.path[0].0,
+            &self.path[0].1,
             should_enforce,
         )?;
 
         // Check levels between leaf level and root.
         let mut previous_hash = leaf_hash;
-        for (i, &(ref left_hash, ref right_hash)) in witness.path.iter().enumerate() {
+        for (i, &(ref left_hash, ref right_hash)) in self.path.iter().enumerate() {
             // Check if the previous_hash matches the correct current hash.
             let previous_is_left =
                 AllocatedBit::alloc(&mut cs.ns(|| format!("previous_is_left_{}", i)), || {
@@ -138,10 +126,10 @@ where
     HG::check_evaluation_gadget(cs, parameters, &bytes)
 }
 
-impl<P, HGadget, ConstraintF> AllocGadget<HashMembershipProof<P>, ConstraintF>
-    for MerklePath<P, HGadget, ConstraintF>
+impl<P, HGadget, ConstraintF> AllocGadget<MerkleTreePath<P>, ConstraintF>
+    for MerkleTreePathGadget<P, HGadget, ConstraintF>
 where
-    P: MHTParameters,
+    P: MerkleTreeConfig,
     HGadget: FixedLengthCRHGadget<P::H, ConstraintF>,
     ConstraintF: Field,
 {
@@ -151,7 +139,7 @@ where
     ) -> Result<Self, SynthesisError>
     where
         F: FnOnce() -> Result<T, SynthesisError>,
-        T: Borrow<HashMembershipProof<P>>,
+        T: Borrow<MerkleTreePath<P>>,
     {
         let mut path = Vec::new();
         for (i, &(ref l, ref r)) in value_gen()?.borrow().path.iter().enumerate() {
@@ -165,7 +153,7 @@ where
                 })?;
             path.push((l_hash, r_hash));
         }
-        Ok(MerklePath {
+        Ok(MerkleTreePathGadget {
             path,
         })
     }
@@ -176,7 +164,7 @@ where
     ) -> Result<Self, SynthesisError>
     where
         F: FnOnce() -> Result<T, SynthesisError>,
-        T: Borrow<HashMembershipProof<P>>,
+        T: Borrow<MerkleTreePath<P>>,
     {
         let mut path = Vec::new();
         for (i, &(ref l, ref r)) in value_gen()?.borrow().path.iter().enumerate() {
@@ -191,7 +179,7 @@ where
             path.push((l_hash, r_hash));
         }
 
-        Ok(MerklePath {
+        Ok(MerkleTreePathGadget {
             path,
         })
     }
@@ -208,7 +196,7 @@ mod test {
             FixedLengthCRH,
             FixedLengthCRHGadget,
         },
-        mht::*,
+        merkle_tree::*,
     };
     use algebra::{
         curves::jubjub::JubJubAffine as JubJub,
@@ -234,20 +222,20 @@ mod test {
     type H = PedersenCRH<JubJub, Window4x256>;
     type HG = PedersenCRHGadget<JubJub, Fq, JubJubGadget>;
 
-    struct JubJubMHTParams;
+    struct JubJubMerkleTreeParams;
     
-    impl MHTParameters for JubJubMHTParams {
+    impl MerkleTreeConfig for JubJubMerkleTreeParams {
         const HEIGHT: usize = 32;
         type H = H;
     }
 
-    type JubJubMHT = MerkleHashTree<JubJubMHTParams>;
+    type JubJubMerkleTree = MerkleHashTree<JubJubMerkleTreeParams>;
 
     fn generate_merkle_tree(leaves: &[[u8; 30]], use_bad_root: bool) -> () {
         let mut rng = XorShiftRng::seed_from_u64(9174123u64);
 
         let crh_parameters = Rc::new(H::setup(&mut rng).unwrap());
-        let tree = JubJubMHT::new(crh_parameters.clone(), leaves).unwrap();
+        let tree = JubJubMerkleTree::new(crh_parameters.clone(), leaves).unwrap();
         let root = tree.root();
         let mut satisfied = true;
         for (i, leaf) in leaves.iter().enumerate() {
@@ -290,7 +278,7 @@ mod test {
             println!("constraints from leaf: {}", constraints_from_leaf);
 
             // Allocate Merkle Tree Path
-            let cw = MerklePath::<_, HG, _>::alloc(&mut cs.ns(|| format!("new_witness_{}", i)), || {
+            let cw = MerkleTreePathGadget::<_, HG, _>::alloc(&mut cs.ns(|| format!("new_witness_{}", i)), || {
                 Ok(proof)
             })
             .unwrap();
@@ -301,12 +289,11 @@ mod test {
                 - constraints_from_leaf;
             println!("constraints from path: {}", constraints_from_path);
             let leaf_g: &[UInt8] = leaf_g.as_slice();
-            MerklePathVerifierGadget::<_, HG, _>::check_membership(
+            cw.check_membership(
                 &mut cs.ns(|| format!("new_witness_check_{}", i)),
                 &crh_parameters,
                 &root,
                 &leaf_g,
-                &cw,
             )
             .unwrap();
             if !cs.is_satisfied() {
@@ -330,7 +317,7 @@ mod test {
     }
 
     #[test]
-    fn mht_gadget_test() {
+    fn good_root_test() {
         let mut leaves = Vec::new();
         for i in 0..4u8 {
             let input = [i ; 30];

crypto-primitives/src/merkle_tree/mod.rs

@@ -7,7 +7,7 @@ use std::{fmt, rc::Rc};
 #[cfg(feature = "r1cs")]
 pub mod constraints;
 
-pub trait MHTParameters {
+pub trait MerkleTreeConfig {
     const HEIGHT: usize;
     type H: FixedLengthCRH;
 }
@@ -16,14 +16,18 @@ pub trait MHTParameters {
 /// Our path `is_left_child()` if the boolean in `path` is true.
 #[derive(Derivative)]
 #[derivative(
-    Clone(bound = "P: MHTParameters"),
-    Debug(bound = "P: MHTParameters, <P::H as FixedLengthCRH>::Output: fmt::Debug")
+    Clone(bound = "P: MerkleTreeConfig"),
+    Debug(bound = "P: MerkleTreeConfig, <P::H as FixedLengthCRH>::Output: fmt::Debug")
 )]
-pub struct HashMembershipProof<P: MHTParameters> {
+pub struct MerkleTreePath<P: MerkleTreeConfig> {
     pub(crate) path: Vec<(<P::H as FixedLengthCRH>::Output, <P::H as FixedLengthCRH>::Output)>,
 }
 
-impl<P: MHTParameters> Default for HashMembershipProof<P> {
+pub type MerkleTreeParams<P> = <<P as MerkleTreeConfig>::H as FixedLengthCRH>::Parameters;
+pub type MerkleTreeDigest<P> = <<P as MerkleTreeConfig>::H as FixedLengthCRH>::Output;
+
+
+impl<P: MerkleTreeConfig> Default for MerkleTreePath<P> {
     fn default() -> Self {
         let mut path = Vec::with_capacity(P::HEIGHT as usize);
         for _i in 1..P::HEIGHT as usize {
@@ -35,7 +39,7 @@ impl<P: MHTParameters> Default for HashMembershipProof<P> {
     }
 }
 
-impl<P: MHTParameters> HashMembershipProof<P> {
+impl<P: MerkleTreeConfig> MerkleTreePath<P> {
     pub fn verify<L: ToBytes>(
         &self,
         parameters: &<P::H as FixedLengthCRH>::Parameters,
@@ -76,14 +80,14 @@ impl<P: MHTParameters> HashMembershipProof<P> {
     }
 }
 
-pub struct MerkleHashTree<P: MHTParameters> {
+pub struct MerkleHashTree<P: MerkleTreeConfig> {
     tree:         Vec<<P::H as FixedLengthCRH>::Output>,
     padding_tree: Vec<(<P::H as FixedLengthCRH>::Output, <P::H as FixedLengthCRH>::Output)>,
     parameters:   Rc<<P::H as FixedLengthCRH>::Parameters>,
     root:         Option<<P::H as FixedLengthCRH>::Output>,
 }
 
-impl<P: MHTParameters> MerkleHashTree<P> {
+impl<P: MerkleTreeConfig> MerkleHashTree<P> {
     pub const HEIGHT: u8 = P::HEIGHT as u8;
 
     pub fn blank(parameters: Rc<<P::H as FixedLengthCRH>::Parameters>) -> Self {
@@ -96,7 +100,7 @@ impl<P: MHTParameters> MerkleHashTree<P> {
     }
 
     pub fn new<L: ToBytes>(parameters: Rc<<P::H as FixedLengthCRH>::Parameters>, leaves: &[L]) -> Result<Self, Error> {
-        let new_time = start_timer!(|| "MHT::New");
+        let new_time = start_timer!(|| "MerkleTree::New");
 
         let last_level_size = leaves.len().next_power_of_two();
         let tree_size = 2 * last_level_size - 1;
@@ -177,8 +181,8 @@ impl<P: MHTParameters> MerkleHashTree<P> {
         &self,
         index: usize,
         leaf: &L,
-    ) -> Result<HashMembershipProof<P>, Error> {
-        let prove_time = start_timer!(|| "MHT::GenProof");
+    ) -> Result<MerkleTreePath<P>, Error> {
+        let prove_time = start_timer!(|| "MerkleTree::GenProof");
         let mut path = Vec::new();
 
         let mut buffer = [0u8; 128];
@@ -189,7 +193,7 @@ impl<P: MHTParameters> MerkleHashTree<P> {
 
         // Check that the given index corresponds to the correct leaf.
         if leaf_hash != self.tree[tree_index] {
-            Err(MHTError::IncorrectLeafIndex(tree_index))?
+            Err(MerkleTreeError::IncorrectLeafIndex(tree_index))?
         }
 
         // Iterate from the leaf up to the root, storing all intermediate hash values.
@@ -219,9 +223,9 @@ impl<P: MHTParameters> MerkleHashTree<P> {
         }
         end_timer!(prove_time);
         if path.len() != (Self::HEIGHT - 1) as usize {
-            Err(MHTError::IncorrectPathLength(path.len()))?
+            Err(MerkleTreeError::IncorrectPathLength(path.len()))?
         } else {
-            Ok(HashMembershipProof {
+            Ok(MerkleTreePath {
                 path,
             })
         }
@@ -229,22 +233,22 @@ impl<P: MHTParameters> MerkleHashTree<P> {
 }
 
 #[derive(Debug)]
-pub enum MHTError {
+pub enum MerkleTreeError {
     IncorrectLeafIndex(usize),
     IncorrectPathLength(usize),
 }
 
-impl std::fmt::Display for MHTError {
+impl std::fmt::Display for MerkleTreeError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let msg = match self {
-            MHTError::IncorrectLeafIndex(index) => format!("incorrect leaf index: {}", index),
-            MHTError::IncorrectPathLength(len) => format!("incorrect path length: {}", len),
+            MerkleTreeError::IncorrectLeafIndex(index) => format!("incorrect leaf index: {}", index),
+            MerkleTreeError::IncorrectPathLength(len) => format!("incorrect path length: {}", len),
         };
         write!(f, "{}", msg)
     }
 }
 
-impl std::error::Error for MHTError {
+impl std::error::Error for MerkleTreeError {
     #[inline]
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         None
@@ -357,7 +361,7 @@ pub(crate) fn hash_empty<H: FixedLengthCRH>(
 
 #[cfg(test)]
 mod test {
-    use crate::{crh::{pedersen::*, *}, mht::*};
+    use crate::{crh::{pedersen::*, *}, merkle_tree::*};
     use algebra::curves::jubjub::JubJubAffine as JubJub;
     use rand::SeedableRng;
     use rand_xorshift::XorShiftRng;
@@ -372,20 +376,20 @@ mod test {
 
     type H = PedersenCRH<JubJub, Window4x256>;
 
-    struct JubJubMHTParams;
+    struct JubJubMerkleTreeParams;
     
-    impl MHTParameters for JubJubMHTParams {
+    impl MerkleTreeConfig for JubJubMerkleTreeParams {
         const HEIGHT: usize = 32;
         type H = H;
     }
-    type JubJubMHT = MerkleHashTree<JubJubMHTParams>;
+    type JubJubMerkleTree = MerkleHashTree<JubJubMerkleTreeParams>;
 
 
     fn generate_merkle_tree<L: ToBytes + Clone + Eq>(leaves: &[L]) -> () {
         let mut rng = XorShiftRng::seed_from_u64(9174123u64);
 
         let crh_parameters = Rc::new(H::setup(&mut rng).unwrap());
-        let tree = JubJubMHT::new(crh_parameters.clone(), &leaves).unwrap();
+        let tree = JubJubMerkleTree::new(crh_parameters.clone(), &leaves).unwrap();
         let root = tree.root();
         for (i, leaf) in leaves.iter().enumerate() {
             let proof = tree.generate_proof(i, &leaf).unwrap();
@@ -394,7 +398,7 @@ mod test {
     }
 
     #[test]
-    fn mht_test() {
+    fn good_root_test() {
         let mut leaves = Vec::new();
         for i in 0..4u8 {
             leaves.push([i, i, i, i, i, i, i, i]);
@@ -412,7 +416,7 @@ mod test {
         let mut rng = XorShiftRng::seed_from_u64(13423423u64);
 
         let crh_parameters = Rc::new(H::setup(&mut rng).unwrap());
-        let tree = JubJubMHT::new(crh_parameters.clone(), &leaves).unwrap();
+        let tree = JubJubMerkleTree::new(crh_parameters.clone(), &leaves).unwrap();
         let root = JubJub::zero();
         for (i, leaf) in leaves.iter().enumerate() {
             let proof = tree.generate_proof(i, &leaf).unwrap();
@@ -422,7 +426,7 @@ mod test {
 
     #[should_panic]
     #[test]
-    fn bad_root_mht_test() {
+    fn bad_root_test() {
         let mut leaves = Vec::new();
         for i in 0..4u8 {
             leaves.push([i, i, i, i, i, i, i, i]);