Add LPN and GGM related (#54)

* add lpn and optimizations with multi threads

* update comments

* finish ggm reconstruction, still need optimization

* clippy

* cargo ciplly

* add comments on public functions

* add pado as a contributor

* add assertion and modify documentation

* fix minor bugs

* rebase dev

* fmt

README.md

@@ -54,6 +54,7 @@ See [CONTRIBUTING.md](CONTRIBUTING.md).
 ## Contributors
 
 - [TLSNotary](https://github.com/tlsnotary)
+- [PADO Labs](https://github.com/pado-labs)
 
 
 ### Pronounciation

mpz-core/Cargo.toml

@@ -7,8 +7,9 @@ edition = "2021"
 name = "mpz_core"
 
 [features]
-default = ["cointoss"]
+default = ["cointoss", "rayon"]
 cointoss = ["dep:rand_chacha"]
+rayon = ["dep:rayon"]
 
 [dependencies]
 aes = { workspace = true, features = [] }
@@ -26,6 +27,8 @@ bcs = "0.1.5"
 rand_core = "0.6.4"
 bytemuck = { workspace = true, features = ["derive"] }
 generic-array.workspace = true
+rayon = { workspace = true, optional = true }
+cfg-if.workspace = true
 
 [dev-dependencies]
 rstest.workspace = true
@@ -42,3 +45,7 @@ harness = false
 [[bench]]
 name = "prg"
 harness = false
+
+[[bench]]
+name = "lpn"
+harness = false

mpz-core/benches/ggm.rs

@@ -4,11 +4,11 @@ use mpz_core::{block::Block, ggm_tree::GgmTree};
 #[allow(clippy::all)]
 fn criterion_benchmark(c: &mut Criterion) {
     c.bench_function("ggm::gen::1K", move |bench| {
-        let depth = 11;
+        let depth = 10;
         let ggm = GgmTree::new(depth);
-        let mut tree = vec![Block::ZERO; 1 << (depth - 1)];
-        let mut k0 = vec![Block::ZERO; depth - 1];
-        let mut k1 = vec![Block::ZERO; depth - 1];
+        let mut tree = vec![Block::ZERO; 1 << (depth)];
+        let mut k0 = vec![Block::ZERO; depth];
+        let mut k1 = vec![Block::ZERO; depth];
         let seed = rand::random::<Block>();
         bench.iter(|| {
             black_box(ggm.gen(
@@ -19,6 +19,17 @@ fn criterion_benchmark(c: &mut Criterion) {
             ));
         });
     });
+
+    c.bench_function("ggm::reconstruction::1K", move |bench| {
+        let depth = 10;
+        let ggm = GgmTree::new(depth);
+        let mut tree = vec![Block::ZERO; 1 << (depth)];
+        let k = vec![Block::ZERO; depth];
+        let alpha = vec![false; depth];
+        bench.iter(|| {
+            black_box(ggm.reconstruct(black_box(&mut tree), black_box(&k), black_box(&alpha)))
+        });
+    });
 }
 
 criterion_group!(benches, criterion_benchmark);

mpz-core/benches/lpn.rs

@@ -0,0 +1,57 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use mpz_core::{lpn::LpnEncoder, prg::Prg, Block};
+use std::time::Duration;
+
+fn criterion_benchmark(c: &mut Criterion) {
+    c.bench_function("lpn-rayon-small", move |bench| {
+        let seed = Block::ZERO;
+        let k = 5_060;
+        let n = 166_400;
+        let lpn = LpnEncoder::<10>::new(seed, k);
+        let mut x = vec![Block::ZERO; k as usize];
+        let mut y = vec![Block::ZERO; n];
+        let mut prg = Prg::new();
+        prg.random_blocks(&mut x);
+        prg.random_blocks(&mut y);
+        bench.iter(|| {
+            black_box(lpn.compute(&mut y, &x));
+        });
+    });
+
+    c.bench_function("lpn-rayon-medium", move |bench| {
+        let seed = Block::ZERO;
+        let k = 158_000;
+        let n = 10_168_320;
+        let lpn = LpnEncoder::<10>::new(seed, k);
+        let mut x = vec![Block::ZERO; k as usize];
+        let mut y = vec![Block::ZERO; n];
+        let mut prg = Prg::new();
+        prg.random_blocks(&mut x);
+        prg.random_blocks(&mut y);
+        bench.iter(|| {
+            black_box(lpn.compute(&mut y, &x));
+        });
+    });
+
+    c.bench_function("lpn-rayon-large", move |bench| {
+        let seed = Block::ZERO;
+        let k = 588_160;
+        let n = 10_616_092;
+        let lpn = LpnEncoder::<10>::new(seed, k);
+        let mut x = vec![Block::ZERO; k as usize];
+        let mut y = vec![Block::ZERO; n];
+        let mut prg = Prg::new();
+        prg.random_blocks(&mut x);
+        prg.random_blocks(&mut y);
+        bench.iter(|| {
+            black_box(lpn.compute(&mut y, &x));
+        });
+    });
+}
+
+criterion_group! {
+    name = lpn;
+    config = Criterion::default().warm_up_time(Duration::from_millis(1000)).sample_size(10);
+    targets = criterion_benchmark
+}
+criterion_main!(lpn);

mpz-core/src/ggm_tree.rs

@@ -18,16 +18,20 @@ impl GgmTree {
         Self { tkprp, depth }
     }
 
-    /// Input: `seed`: a seed.
-    /// Output: `tree`: a GGM (binary tree) `tree`, with size `2^{depth-1}`
-    /// Output: `k0`: XORs of all the left-node values in each level, with size `depth-1`.
-    /// Output: `k1`: XORs of all the right-node values in each level, with size `depth-1`.
-    /// This implementation is adapted from EMP Toolkit.
+    /// Create a GGM tree in-place.
+    ///
+    /// # Arguments
+    ///
+    /// * `seed` - a seed.
+    /// * `tree` - the destination to write the GGM (binary tree) `tree`, with size `2^{depth}`.
+    /// * `k0` - XORs of all the left-node values in each level, with size `depth`.
+    /// * `k1`- XORs of all the right-node values in each level, with size `depth`.
+    // This implementation is adapted from EMP Toolkit.
     pub fn gen(&self, seed: Block, tree: &mut [Block], k0: &mut [Block], k1: &mut [Block]) {
-        assert!(tree.len() == 1 << (self.depth - 1));
-        assert!(k0.len() == self.depth - 1);
-        assert!(k1.len() == self.depth - 1);
-        let mut buf = vec![Block::ZERO; 8];
+        assert_eq!(tree.len(), 1 << (self.depth));
+        assert_eq!(k0.len(), self.depth);
+        assert_eq!(k1.len(), self.depth);
+        let mut buf = [Block::ZERO; 8];
         self.tkprp.expand_1to2(tree, seed);
         k0[0] = tree[0];
         k1[0] = tree[1];
@@ -37,9 +41,11 @@ impl GgmTree {
         k1[1] = buf[1] ^ buf[3];
         tree[0..4].copy_from_slice(&buf[0..4]);
 
-        for h in 2..self.depth - 1 {
+        for h in 2..self.depth {
             k0[h] = Block::ZERO;
             k1[h] = Block::ZERO;
+
+            // How many nodes there are in this layer
             let sz = 1 << h;
             for i in (0..=sz - 4).rev().step_by(4) {
                 self.tkprp.expand_4to8(&mut buf, &tree[i..]);
@@ -56,43 +62,108 @@ impl GgmTree {
             }
         }
     }
+
+    /// Reconstruct the GGM tree except the value in a given position.
+    ///
+    /// This reconstructs the GGM tree entirely except `tree[pos] == Block::ZERO`. The bit decomposition of `pos` is the complement of `alpha`. i.e., `pos[i] = 1 xor alpha[i]`.
+    ///
+    /// # Arguments
+    ///
+    /// * `k` - a slice of blocks with length `depth`, the values of k are chosen via OT from k0 and k1. For the i-th value, if alpha[i] == 1, k[i] = k1[i]; else k[i] = k0[i].
+    /// * `alpha` - a slice of bits with length `depth`.
+    /// * `tree` - the destination to write the GGM tree.
+    pub fn reconstruct(&self, tree: &mut [Block], k: &[Block], alpha: &[bool]) {
+        assert_eq!(tree.len(), 1 << (self.depth));
+        assert_eq!(k.len(), self.depth);
+        assert_eq!(alpha.len(), self.depth);
+
+        let mut pos = 0;
+        for i in 1..=self.depth {
+            pos *= 2;
+            tree[pos] = Block::ZERO;
+            tree[pos + 1] = Block::ZERO;
+            if !alpha[i - 1] {
+                self.reconstruct_layer(i, false, pos, k[i - 1], tree);
+                pos += 1;
+            } else {
+                self.reconstruct_layer(i, true, pos + 1, k[i - 1], tree);
+            }
+        }
+    }
+
+    // Handle each layer.
+    fn reconstruct_layer(
+        &self,
+        depth: usize,
+        left_or_right: bool,
+        pos: usize,
+        k: Block,
+        tree: &mut [Block],
+    ) {
+        // How many nodes there are in this layer
+        let sz = 1 << depth;
+
+        let mut sum = Block::ZERO;
+        let start = if left_or_right { 1 } else { 0 };
+
+        for i in (start..sz).step_by(2) {
+            sum ^= tree[i];
+        }
+        tree[pos] = sum ^ k;
+
+        if depth == (self.depth) {
+            return;
+        }
+
+        let mut buf = [Block::ZERO; 8];
+        if sz == 2 {
+            self.tkprp.expand_2to4(&mut buf, tree);
+            tree[0..4].copy_from_slice(&buf[0..4]);
+        } else {
+            for i in (0..=sz - 4).rev().step_by(4) {
+                self.tkprp.expand_4to8(&mut buf, &tree[i..]);
+                tree[2 * i..2 * i + 8].copy_from_slice(&buf);
+            }
+        }
+    }
 }
 
 #[test]
 fn ggm_test() {
+    use crate::ggm_tree::GgmTree;
+    use crate::Block;
+
     let depth = 3;
-    let mut tree = vec![Block::ZERO; 1 << (depth - 1)];
-    let mut k0 = vec![Block::ZERO; depth - 1];
-    let mut k1 = vec![Block::ZERO; depth - 1];
+    let mut tree = vec![Block::ZERO; 1 << depth];
+    let mut k0 = vec![Block::ZERO; depth];
+    let mut k1 = vec![Block::ZERO; depth];
+    let mut k = vec![Block::ZERO; depth];
+    let alpha = [false, true, false];
+    let mut pos = 0;
+
+    for a in alpha {
+        pos <<= 1;
+        if !a {
+            pos += 1;
+        }
+    }
 
     let ggm = GgmTree::new(depth);
 
     ggm.gen(Block::ZERO, &mut tree, &mut k0, &mut k1);
 
-    // Test vectors are from EMP Toolkit.
-    assert_eq!(
-        tree,
-        [
-            Block::from(0x92A6DDEAA3E99F9BECB268BD9EF67C91_u128.to_le_bytes()),
-            Block::from(0x9E7E9C02ED1E62385EE8A9EDDC63A2B5_u128.to_le_bytes()),
-            Block::from(0xBD4B85E90AACBD106694537DB6251264_u128.to_le_bytes()),
-            Block::from(0x230485DC4360014833E07D8D914411A2_u128.to_le_bytes()),
-        ]
-    );
-
-    assert_eq!(
-        k0,
-        [
-            Block::from(0x2E2B34CA59FA4C883B2C8AEFD44BE966_u128.to_le_bytes()),
-            Block::from(0x2FED5803A945228B8A263BC028D36EF5_u128.to_le_bytes()),
-        ]
-    );
-
-    assert_eq!(
-        k1,
-        [
-            Block::from(0x7E46C568D1CD4972BB1A61F95DD80EDC_u128.to_le_bytes()),
-            Block::from(0xBD7A19DEAE7E63706D08D4604D27B317_u128.to_le_bytes()),
-        ]
-    );
+    for i in 0..depth {
+        if alpha[i] {
+            k[i] = k1[i];
+        } else {
+            k[i] = k0[i];
+        }
+    }
+
+    let mut tree_reconstruct = vec![Block::ZERO; 1 << depth];
+    ggm.reconstruct(&mut tree_reconstruct, &k, &alpha);
+
+    assert_eq!(tree_reconstruct[pos], Block::ZERO);
+    tree_reconstruct[pos] = tree[pos];
+    assert_eq!(tree, tree_reconstruct);
 }

mpz-core/src/lib.rs

@@ -8,7 +8,9 @@ pub mod cointoss;
 pub mod commit;
 pub mod ggm_tree;
 pub mod hash;
+pub mod lpn;
 pub mod prg;
+pub mod prp;
 pub mod serialize;
 pub mod tkprp;
 pub mod utils;