From 1195f0fdc27892750b14878cb4ae70d59f6d0bd6 Mon Sep 17 00:00:00 2001
From: Gijs Van Laer <gijs.vanlaer@gmail.com>
Date: Fri, 14 Jun 2019 19:57:52 -0400
Subject: [PATCH] ped92: add methods to CSParams

---
 src/ped92.rs | 112 ++++++++++++++++++---------------------------------
 1 file changed, 39 insertions(+), 73 deletions(-)

diff --git a/src/ped92.rs b/src/ped92.rs
index 429860b..d2ce75d 100644
--- a/src/ped92.rs
+++ b/src/ped92.rs
@@ -1,19 +1,7 @@
-// commit_schemes.rs
-extern crate serde;
-
-use serialization_wrappers;
-use std::fmt;
+// ped92.rs
 use rand::{thread_rng, Rng};
-use bn::{Group, Fr, G1, G2};
 use pairing::{Engine, CurveProjective, CurveAffine};
 use ff::Rand;
-use clsigs;
-use debug_elem_in_hex;
-use bincode::SizeLimit::Infinite;
-use bincode::rustc_serialize::encode;
-use sodiumoxide::crypto::hash::sha512;
-
-use serde::{Serialize, Deserialize};
 
 #[derive(Clone)]
 pub struct PublicKey<E: Engine> {
@@ -125,69 +113,47 @@ pub fn ped92_decommit<E: Engine>(pk: &PublicKey<E>, cm: &Commitment<E>, m: E::Fr
 }
 
 
-/*
-Implements the setup algorithm for the Pedersen92 commitment scheme over
-a vector of messages.
-*/
 
-pub fn setup<E: Engine>(len: usize, pub_bases: Vec<E::G2>, h: E::G2) -> CSParams<E> {
-    let rng = &mut thread_rng();
-    //let base_h = h.unwrap_or(G2::random(rng));
-    let mut p: Vec<E::G2> = Vec::new();
-    p.push(h);
-
-    let _p = pub_bases;
-    for i in 0.._p.len() {
-        p.push(_p[i]);
+impl<E: Engine> CSParams<E> {
+    /*
+    Implements the setup algorithm for the Pedersen92 commitment scheme over
+    a vector of messages.
+    */
+    pub fn setup_gen_params<R: Rng>(rng: &mut R, len: usize) -> Self {
+        let mut p: Vec<E::G2> = Vec::new();
+        for i in 0..len {
+            p.push(E::G2::rand(rng));
+        }
+        return CSParams { pub_bases: p };
     }
-    return CSParams { pub_bases: p };
-}
 
-pub fn setup_gen_params<E: Engine>(len: usize) -> CSParams<E> {
-    let rng = &mut thread_rng();
-
-    let mut p: Vec<E::G2> = Vec::new();
-    for i in 0..len {
-        p.push(E::G2::rand(rng));
+    pub fn commit<R: Rng>(&self, rng: &mut R, x: &Vec<E::Fr>, r: E::Fr) -> Commitment<E> {
+        //let r = R.unwrap_or(Fr::random(rng));
+        // c = g1^m1 * ... * gn^mn * h^r
+        let mut c = self.pub_bases[0].clone();
+        c.mul_assign(r);
+        for i in 1..x.len() {
+            let mut basis = self.pub_bases[i];
+            basis.mul_assign(x[i]);
+            c.add_assign(&basis);
+        }
+        // return (c, r) <- r
+        Commitment { c, r }
     }
-    return CSParams { pub_bases: p };
-}
 
-pub fn commit<E: Engine>(csp: &CSParams<E>, x: &Vec<E::Fr>, r: E::Fr) -> Commitment<E> {
-    let rng = &mut thread_rng();
-
-    //let r = R.unwrap_or(Fr::random(rng));
-    // c = g1^m1 * ... * gn^mn * h^r
-    //println!("(commit) index: 0");
-    let mut c = csp.pub_bases[0].clone();
-    c.mul_assign(r);
-    for i in 1..x.len() {
-        //println!("(commit) index: {}", i);
-        let mut basis = csp.pub_bases[i];
-        basis.mul_assign(x[i]);
-        c.add_assign(&basis);
+    pub fn decommit(&self, cm: &Commitment<E>, x: &Vec<E::Fr>) -> bool {
+        let l = x.len();
+        // pub_base[0] => h, x[0] => r
+        // check that cm.r == x[0]
+        let mut dc = self.pub_bases[0].clone();
+        dc.mul_assign(cm.r.clone());
+        for i in 1..l {
+            let mut basis = self.pub_bases[i];
+            basis.mul_assign(x[i]);
+            dc.add_assign(&basis);
+        }
+        return dc == cm.c && cm.r == x[0];
     }
-    // return (c, r) <- r
-    let commitment = Commitment { c, r };
-
-    // debugging
-    //println!("{}", commitment);
-    return commitment;
-}
-
-pub fn decommit<E: Engine>(csp: &CSParams<E>, cm: &Commitment<E>, x: &Vec<E::Fr>) -> bool {
-    let l = x.len();
-    // pub_base[0] => h, x[0] => r
-    // check that cm.r == x[0]
-    // assert!(cm.r == x[0]);
-    let mut dc = csp.pub_bases[0].clone();
-    dc.mul_assign(cm.r.clone());
-    for i in 1..l {
-        let mut basis = csp.pub_bases[i];
-        basis.mul_assign(x[i]);
-        dc.add_assign(&basis);
-    }
-    return dc == cm.c && cm.r == x[0];
 }
 
 #[cfg(test)]
@@ -215,15 +181,15 @@ mod tests {
     fn commit_n_message_works() {
         let rng = &mut thread_rng();
         let len = 3;
-        let csp = setup_gen_params::<Bls12>(len);
+        let csp = CSParams::<Bls12>::setup_gen_params(rng, len);
 
         let mut m: Vec<Fr> = Vec::new();
         for i in 0..len {
             m.push(Fr::rand(rng));
         }
         let r = m[0].clone();
-        let c = commit(&csp, &m, r);
+        let c = csp.commit(rng, &m, r);
 
-        assert_eq!(true, decommit(&csp, &c, &m));
+        assert_eq!(true, csp.decommit( &c, &m));
     }
 }