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Parameterize the generator in RedJubjub

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Per the specification, the generator is different between BindingSig and
SpendAuthSig.
This commit is contained in:
Jack Grigg 2018-04-26 22:30:37 +01:00
parent 4eab1fc68a
commit e94dbf2523
No known key found for this signature in database
GPG Key ID: 665DBCD284F7DAFF
1 changed files with 44 additions and 42 deletions
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86
src/redjubjub.rs
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@ -84,7 +84,13 @@ impl<E: JubjubEngine> PrivateKey<E> {
write_scalar::<E, W>(&self.0, writer)
}
pub fn sign<R: Rng>(&self, msg: &[u8], rng: &mut R, params: &E::Params) -> Signature {
pub fn sign<R: Rng>(
&self,
msg: &[u8],
rng: &mut R,
p_g: FixedGenerators,
params: &E::Params,
) -> Signature {
// T = (l_H + 128) bits of randomness
// For H*, l_H = 512 bits
let mut t = [0u8; 80];
@ -93,10 +99,8 @@ impl<E: JubjubEngine> PrivateKey<E> {
// r = H*(T || M)
let r = h_star::<E>(&t[..], msg);
// R = r . G
let r_g = params
.generator(FixedGenerators::SpendingKeyGenerator)
.mul(r, params);
// R = r . P_G
let r_g = params.generator(p_g).mul(r, params);
let mut rbar = [0u8; 32];
r_g.write(&mut rbar[..])
.expect("Jubjub points should serialize to 32 bytes");
@ -114,19 +118,13 @@ impl<E: JubjubEngine> PrivateKey<E> {
}
impl<E: JubjubEngine> PublicKey<E> {
pub fn from_private(privkey: &PrivateKey<E>, params: &E::Params) -> Self {
let res = params
.generator(FixedGenerators::SpendingKeyGenerator)
.mul(privkey.0, params)
.into();
pub fn from_private(privkey: &PrivateKey<E>, p_g: FixedGenerators, params: &E::Params) -> Self {
let res = params.generator(p_g).mul(privkey.0, params).into();
PublicKey(res)
}
pub fn randomize(&self, alpha: E::Fs, params: &E::Params) -> Self {
let res: Point<E, Unknown> = params
.generator(FixedGenerators::SpendingKeyGenerator)
.mul(alpha, params)
.into();
pub fn randomize(&self, alpha: E::Fs, p_g: FixedGenerators, params: &E::Params) -> Self {
let res: Point<E, Unknown> = params.generator(p_g).mul(alpha, params).into();
let res = res.add(&self.0, params);
PublicKey(res)
}
@ -140,7 +138,13 @@ impl<E: JubjubEngine> PublicKey<E> {
self.0.write(writer)
}
pub fn verify(&self, msg: &[u8], sig: &Signature, params: &E::Params) -> bool {
pub fn verify(
&self,
msg: &[u8],
sig: &Signature,
p_g: FixedGenerators,
params: &E::Params,
) -> bool {
// c = H*(Rbar || M)
let c = h_star::<E>(&sig.rbar[..], msg);
@ -154,12 +158,8 @@ impl<E: JubjubEngine> PublicKey<E> {
};
// S < order(G)
s.into_repr() < E::Fs::char() &&
// S . G = R + c . vk
self.0.mul(c, params).add(&r, params)
== params
.generator(FixedGenerators::SpendingKeyGenerator)
.mul(s, params)
.into()
// S . P_G = R + c . vk
self.0.mul(c, params).add(&r, params) == params.generator(p_g).mul(s, params).into()
}
}
@ -175,13 +175,14 @@ mod tests {
#[test]
fn round_trip_serialization() {
let rng = &mut thread_rng();
let p_g = FixedGenerators::SpendingKeyGenerator;
let params = &JubjubBls12::new();
for _ in 0..1000 {
let sk = PrivateKey::<Bls12>(rng.gen());
let vk = PublicKey::from_private(&sk, params);
let vk = PublicKey::from_private(&sk, p_g, params);
let msg = b"Foo bar";
let sig = sk.sign(msg, rng, params);
let sig = sk.sign(msg, rng, p_g, params);
let mut sk_bytes = [0u8; 32];
let mut vk_bytes = [0u8; 32];
@ -191,50 +192,51 @@ mod tests {
sig.write(&mut sig_bytes[..]).unwrap();
let sk_2 = PrivateKey::<Bls12>::read(&sk_bytes[..]).unwrap();
let vk_2 = PublicKey::from_private(&sk_2, params);
let vk_2 = PublicKey::from_private(&sk_2, p_g, params);
let mut vk_2_bytes = [0u8; 32];
vk_2.write(&mut vk_2_bytes[..]).unwrap();
assert!(vk_bytes == vk_2_bytes);
let vk_2 = PublicKey::<Bls12>::read(&vk_bytes[..], params).unwrap();
let sig_2 = Signature::read(&sig_bytes[..]).unwrap();
assert!(vk.verify(msg, &sig_2, params));
assert!(vk_2.verify(msg, &sig, params));
assert!(vk_2.verify(msg, &sig_2, params));
assert!(vk.verify(msg, &sig_2, p_g, params));
assert!(vk_2.verify(msg, &sig, p_g, params));
assert!(vk_2.verify(msg, &sig_2, p_g, params));
}
}
#[test]
fn random_signatures() {
let rng = &mut thread_rng();
let p_g = FixedGenerators::SpendingKeyGenerator;
let params = &JubjubBls12::new();
for _ in 0..1000 {
let sk = PrivateKey::<Bls12>(rng.gen());
let vk = PublicKey::from_private(&sk, params);
let vk = PublicKey::from_private(&sk, p_g, params);
let msg1 = b"Foo bar";
let msg2 = b"Spam eggs";
let sig1 = sk.sign(msg1, rng, params);
let sig2 = sk.sign(msg2, rng, params);
let sig1 = sk.sign(msg1, rng, p_g, params);
let sig2 = sk.sign(msg2, rng, p_g, params);
assert!(vk.verify(msg1, &sig1, params));
assert!(vk.verify(msg2, &sig2, params));
assert!(!vk.verify(msg1, &sig2, params));
assert!(!vk.verify(msg2, &sig1, params));
assert!(vk.verify(msg1, &sig1, p_g, params));
assert!(vk.verify(msg2, &sig2, p_g, params));
assert!(!vk.verify(msg1, &sig2, p_g, params));
assert!(!vk.verify(msg2, &sig1, p_g, params));
let alpha = rng.gen();
let rsk = sk.randomize(alpha);
let rvk = vk.randomize(alpha, params);
let rvk = vk.randomize(alpha, p_g, params);
let sig1 = rsk.sign(msg1, rng, params);
let sig2 = rsk.sign(msg2, rng, params);
let sig1 = rsk.sign(msg1, rng, p_g, params);
let sig2 = rsk.sign(msg2, rng, p_g, params);
assert!(rvk.verify(msg1, &sig1, params));
assert!(rvk.verify(msg2, &sig2, params));
assert!(!rvk.verify(msg1, &sig2, params));
assert!(!rvk.verify(msg2, &sig1, params));
assert!(rvk.verify(msg1, &sig1, p_g, params));
assert!(rvk.verify(msg2, &sig2, p_g, params));
assert!(!rvk.verify(msg1, &sig2, p_g, params));
assert!(!rvk.verify(msg2, &sig1, p_g, params));
}
}
}