Merge pull request #1 from boltlabs-inc/ped92-generics

Ped92 generics

src/lib.rs

@@ -65,6 +65,7 @@ pub mod ote;
 pub mod cl;
 pub mod clsigs;
 pub mod commit_scheme;
+pub mod ped92;
 pub mod clproto;
 pub mod serialization_wrappers;
 

src/ped92.rs

@@ -0,0 +1,192 @@
+// ped92.rs
+use rand::{thread_rng, Rng};
+use pairing::{Engine, CurveProjective, CurveAffine};
+use ff::Rand;
+
+#[derive(Clone)]
+pub struct CSPublicKey<E: Engine> {
+    g: E::G2,
+    h: E::G2,
+}
+
+#[derive(Clone)]
+pub struct Commitment<E: Engine> {
+    pub c: E::G2,
+    pub r: E::Fr,
+}
+
+#[derive(Clone)]
+pub struct CSMultiPublicKey<E: Engine> {
+    pub pub_bases: Vec<E::G2>
+}
+
+//impl<E: Engine> fmt::Display for CSPublicKey<E> {
+//    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+//        let g_vec: Vec<u8> = encode(&self.g, Infinite).unwrap();
+//        let h_vec: Vec<u8> = encode(&self.h, Infinite).unwrap();
+//        let mut g_s = String::new();
+//        for x in g_vec.iter() {
+//            g_s = format!("{}{:x}", g_s, x);
+//        }
+//
+//        let mut h_s = String::new();
+//        for y in h_vec.iter() {
+//            h_s = format!("{}{:x}", h_s, y);
+//        }
+//
+//        write!(f, "PK : (g=0x{}, h=0x{})", g_s, h_s)
+//    }
+//}
+
+//impl<E: Engine> fmt::Display for Commitment<E> {
+//    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+//        let c_vec: Vec<u8> = encode(&self.c, Infinite).unwrap();
+//        let mut c_s = String::new();
+//        for x in c_vec.iter() {
+//            c_s = format!("{}{:x}", c_s, x);
+//        }
+//
+//        let d_vec: Vec<u8> = encode(&self.r, Infinite).unwrap();
+//        let mut d_s = String::new();
+//        for x in d_vec.iter() {
+//            d_s = format!("{}{:x}", d_s, x);
+//        }
+//        write!(f, "Commitment : (c=0x{}, r=0x{})", c_s, d_s)
+//    }
+//}
+
+impl<E: Engine> CSPublicKey<E> {
+    /*
+Implements the setup algorithm for the Pedersen92 commitment scheme
+*/
+    pub fn setup<R: Rng>(rng: &mut R) -> Self {
+        let g = E::G2::rand(rng);
+        let h = E::G2::rand(rng);
+        let pk = CSPublicKey { g, h };
+        return pk;
+    }
+
+    /*
+commit(pk, msg) -> cm where
+- pk is the public key generated from setup()
+- msg is the message structure for the commitment scheme
+- cm is the output commitment message for the given message
+*/
+    pub fn commit<R: Rng>(&self, rng: &mut R, m: E::Fr, R: Option<E::Fr>) -> Commitment<E> {
+        let r = R.unwrap_or(E::Fr::rand(rng));
+        //let r = Fr::random(rng);
+
+        //let m = msg.hash();
+        let p = "commit -> m";
+        // c = g^m * h^r
+        let mut c = self.g.clone();
+        c.mul_assign(m);
+        let mut h = self.h.clone();
+        h.mul_assign(r);
+        c.add_assign(&h);
+        // return (c, r) <- d=r
+        let commitment = Commitment { c, r };
+
+        // debugging
+        return commitment;
+    }
+
+    /*
+decommit(pk, cm, msg) -> bool where
+- pk is the public key generated from setup()
+- cm is the commitment
+- m is the message to validate
+- outputs T/F for whether the cm is a valid commitment to the msg
+*/
+    pub fn decommit(&self, cm: &Commitment<E>, m: E::Fr) -> bool {
+        let p = "decommit -> m";
+
+        let mut dm = self.g.clone();
+        dm.mul_assign(m);
+        let mut h = self.h.clone();
+        h.mul_assign(cm.r.clone());
+        dm.add_assign(&h);
+        return dm == cm.c;
+    }
+}
+
+
+impl<E: Engine> CSMultiPublicKey<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 CSMultiPublicKey { pub_bases: p };
+    }
+
+    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 }
+    }
+
+    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];
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pairing::bls12_381::{Bls12, Fr};
+    use ff::Field;
+
+    #[test]
+    fn commit_one_message_works() {
+        let rng = &mut thread_rng();
+        let pk = CSPublicKey::<Bls12>::setup(rng);
+
+        let m1 = Fr::rand(rng);
+        let mut m2 = m1.clone();
+        m2.add_assign(&Fr::one());
+        let r = Fr::rand(rng);
+        let c = pk.commit(rng, m1, Some(r));
+
+        assert_eq!(true, pk.decommit(&c, m1));
+        assert_eq!(false, pk.decommit(&c, m2));
+    }
+
+    #[test]
+    fn commit_n_message_works() {
+        let rng = &mut thread_rng();
+        let len = 3;
+        let csp = CSMultiPublicKey::<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 = csp.commit(rng, &m, r);
+
+        assert_eq!(true, csp.decommit(&c, &m));
+    }
+}