Performance Improvements thanks to @hdevalence

src/lib.rs

@@ -1,4 +1,5 @@
 #![deny(missing_docs)]
+#![feature(array_methods)]
 #![feature(external_doc)]
 #![doc(include = "../README.md")]
 #![doc(include = "../ANONYMITY.md")]
@@ -7,13 +8,14 @@ use curve25519_dalek::constants::RISTRETTO_BASEPOINT_POINT;
 use curve25519_dalek::digest::Digest;
 use curve25519_dalek::ristretto::RistrettoPoint;
 use curve25519_dalek::scalar::Scalar;
+use curve25519_dalek::traits::MultiscalarMul;
 use rand::rngs::OsRng;
 use serde::Deserialize;
 use serde::Serialize;
 use sha3::Sha3_512;
 use std::fmt;
 use std::fmt::{Display, Formatter};
-use std::ops::{Add, Mul, Sub};
+use std::ops::{Mul, Sub};
 
 /// A tag is a probabilistic cryptographic structure. When constructed for a given `FuzzyPublicKey`
 /// it will pass the `FuzzyDetectionKey::test` 100% of the time. For other public keys
@@ -73,10 +75,7 @@ impl FuzzyDetectionKey {
         for s in self.0.iter() {
             hash.update(s.as_bytes())
         }
-        format!(
-            "{}",
-            hex::encode(hash.finalize().as_slice()),
-        )
+        format!("{}", hex::encode(hash.finalize().as_slice()),)
     }
 }
 
@@ -135,7 +134,7 @@ impl FuzzyDetectionKey {
         //      w = g^m + g^(z-m)
         //      w = g^z
         // See below for a full explanation as to the reason for this:
-        let w = g.mul(m).add(tag.u.mul(tag.y));
+        let w = RistrettoPoint::multiscalar_mul(&[m, tag.y], &[g, tag.u]);
 
         // for each secret key part...
         let mut result = true;
@@ -166,7 +165,6 @@ impl FuzzyDetectionKey {
 pub struct FuzzyPublicKey(Vec<RistrettoPoint>);
 
 impl FuzzyPublicKey {
-
     /// a convenient id for a public key for internal accounting purposes
     /// do not expose this to applications
     pub fn id(&self) -> String {
@@ -174,10 +172,7 @@ impl FuzzyPublicKey {
         for s in self.0.iter() {
             hash.update(s.compress().as_bytes())
         }
-        format!(
-            "{}",
-            hex::encode(hash.finalize().as_slice()),
-        )
+        format!("{}", hex::encode(hash.finalize().as_slice()),)
     }
 
     /// generate a new tag for this public key
@@ -229,8 +224,6 @@ impl FuzzyPublicKey {
     }
 }
 
-
-
 /// An identity keypair for generating and validating fuzzy meta tags.
 #[derive(Debug, Serialize, Deserialize)]
 pub struct FuzzyTagKeyPair {
@@ -279,24 +272,21 @@ impl FuzzyTagKeyPair {
         self.secret_key.extract(n)
     }
 
-    /// a hash function that takes 3 risretto points as a parameter and outputs 0 or 1.
+    /// a hash function that takes 3 ristretto points as a parameter and outputs 0 or 1.
     fn h(u: RistrettoPoint, h: RistrettoPoint, w: RistrettoPoint) -> u8 {
-        let hash = sha3::Sha3_256::digest(
-            format!(
-                "{}{}{}",
-                hex::encode(u.compress().as_bytes()),
-                hex::encode(h.compress().as_bytes()),
-                hex::encode(w.compress().as_bytes())
-            )
-            .as_bytes(),
-        );
-        return hash.as_slice()[0] & 0x01;
+        let mut hash = sha3::Sha3_256::new();
+        hash.update(u.compress().as_bytes());
+        hash.update(h.compress().as_bytes());
+        hash.update(w.compress().as_bytes());
+        return hash.finalize().as_slice()[0] & 0x01;
     }
 
-    /// a hash function which takes a ristretto point and a vector of ciphertexts and ouputs a
+    /// a hash function which takes a ristretto point and a vector of ciphertexts and outputs a
     /// ristretto scalar.
     fn g(u: RistrettoPoint, points: &BitVec) -> Scalar {
-        Scalar::hash_from_bytes::<Sha3_512>(format!("{}{}", hex::encode(u.compress().as_bytes()), hex::encode(points.to_bytes())).as_bytes())
+        let mut input = points.to_bytes().as_slice().to_vec();
+        input.extend_from_slice(u.compress().as_bytes());
+        Scalar::hash_from_bytes::<Sha3_512>(input.as_slice())
     }
 }