From 983af331b2760c6b438abbd50cee7614c839c937 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Wed, 14 Sep 2016 15:04:14 -0600
Subject: [PATCH] Improve performance of verification.

---
 Cargo.lock       |  6 +++---
 Cargo.toml       |  2 +-
 snark/Cargo.toml |  2 +-
 src/lib.rs       |  1 -
 src/sequences.rs | 36 ------------------------------------
 src/spairs.rs    | 35 +++++++++++++++++++++++++----------
 6 files changed, 30 insertions(+), 52 deletions(-)
 delete mode 100644 src/sequences.rs

diff --git a/Cargo.lock b/Cargo.lock
index c64c967..1cf2a74 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,7 +3,7 @@ name = "mpc"
 version = "0.0.1"
 dependencies = [
  "bincode 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "bn 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bn 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "crossbeam 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -22,7 +22,7 @@ dependencies = [
 
 [[package]]
 name = "bn"
-version = "0.2.2"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "byteorder 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -77,7 +77,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "snark"
 version = "0.0.1"
 dependencies = [
- "bn 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bn 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "gcc 0.3.32 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index 1401eec..4f9f04b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -11,7 +11,7 @@ readme = "README.md"
 
 [dependencies]
 snark = { path = "./snark/" }
-bn = "0.2.2"
+bn = "0.2.3"
 crossbeam = "0.2.9"
 rand = "0.3.14"
 rustc-serialize = "~0.3.19"
diff --git a/snark/Cargo.toml b/snark/Cargo.toml
index ec820a4..f76cf41 100644
--- a/snark/Cargo.toml
+++ b/snark/Cargo.toml
@@ -16,4 +16,4 @@ gcc = "0.3.*"
 [dependencies]
 libc = "0.2.*"
 lazy_static = "0.1.*"
-bn = "0.2.2"
+bn = "0.2.3"
diff --git a/src/lib.rs b/src/lib.rs
index e90f886..7e9586d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -6,7 +6,6 @@ extern crate rustc_serialize;
 
 mod taupowers;
 mod multicore;
-mod sequences;
 mod qap;
 mod spairs;
 mod transcript;
diff --git a/src/sequences.rs b/src/sequences.rs
deleted file mode 100644
index eab9f2a..0000000
--- a/src/sequences.rs
+++ /dev/null
@@ -1,36 +0,0 @@
-pub struct Sequences<'a, T: 'a, I: Iterator<Item=&'a T>> {
-    v: I,
-    last: Option<&'a T>
-}
-
-impl<'a, T: 'a, I: Iterator<Item=&'a T>> Sequences<'a, T, I> {
-    pub fn new(v: I) -> Self {
-        Sequences { v: v, last: None }
-    }
-}
-
-impl<'a, T: 'a, I: Iterator<Item=&'a T>> Iterator for Sequences<'a, T, I> {
-    type Item = (&'a T, &'a T);
-
-    fn next(&mut self) -> Option<(&'a T, &'a T)> {
-        match (self.last, self.v.next()) {
-            (Some(a), Some(b)) => {
-                self.last = Some(b);
-                Some((a, b))
-            },
-            (None, Some(b)) => {
-                self.last = Some(b);
-                self.next()
-            },
-            _ => None
-        }
-    }
-}
-
-#[test]
-fn test_sequences() {
-    let a = vec![10, 57, 34, 12];
-    let b: Vec<(&usize, &usize)> = Sequences::new(a.iter()).collect();
-    let expected = vec![(&a[0], &a[1]), (&a[1], &a[2]), (&a[2], &a[3])];
-    assert_eq!(b, expected);
-}
diff --git a/src/spairs.rs b/src/spairs.rs
index 17c47dc..12b32a0 100644
--- a/src/spairs.rs
+++ b/src/spairs.rs
@@ -2,7 +2,6 @@ use bn::*;
 use rand::Rng;
 use snark::*;
 use rustc_serialize::{Encodable, Encoder, Decodable, Decoder};
-use sequences::*;
 use multicore::*;
 use crossbeam;
 
@@ -394,18 +393,34 @@ pub fn checkvec<R: Rng, Group1: Group, Group2: Group>(
 where Group1: Pairing<Group2>
 {
     assert!(v1.len() == v2.len());
-    let mut p = Group1::zero();
-    let mut q = Group1::zero();
 
-    for i in v1.iter().zip(v2.iter()) {
-        let alpha = Fr::random(rng);
-        p = p + *i.0 * alpha;
-        q = q + *i.1 * alpha;
-    }
+    crossbeam::scope(|scope| {
+        let window_size = v1.len() / THREADS;
+        let mut tasks = vec![];
+        for i in v1.chunks(window_size).zip(v2.chunks(window_size)) {
+            tasks.push(scope.spawn(move || {
+                let rng = &mut ::rand::thread_rng();
+                let mut p = Group1::zero();
+                let mut q = Group1::zero();
 
-    if p.is_zero() || q.is_zero() { return false; }
+                for (a, b) in i.0.iter().zip(i.1.iter()) {
+                    let alpha = Fr::random(rng);
+                    p = p + (*a * alpha);
+                    q = q + (*b * alpha);
+                }
 
-    same_power(&Spair::new(p, q).unwrap(), &a)
+                if p.is_zero() || q.is_zero() {
+                    false
+                } else {
+                    same_power(&Spair::new(p, q).unwrap(), a)
+                }
+            }));
+        }
+
+        assert!(tasks.len() >= THREADS);
+
+        tasks.into_iter().map(|t| t.join()).all(|r| r)
+    })
 }
 
 pub fn checkseq<R: Rng, Group1: Group, Group2: Group>(