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Merge pull request #12 from dragan2234/develop
Merge banderwagon branch to develop
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| use ark_serialize::CanonicalSerialize; | ||
| use banderwagon::Element; | ||
|
|
||
| use crate::{ipa::slow_vartime_multiscalar_mul, lagrange_basis::LagrangeBasis}; | ||
|
|
||
| #[derive(Debug, Clone)] | ||
| pub struct CRS { | ||
| pub n: usize, | ||
| pub G: Vec<Element>, | ||
| pub Q: Element, | ||
| } | ||
|
|
||
| impl CRS { | ||
| pub fn new(n: usize, seed: &'static [u8]) -> CRS { | ||
| // TODO generate the Q value from the seed also | ||
| // TODO: this will also make assert_dedup work as expected | ||
| // TODO: since we should take in `Q` too | ||
| let G: Vec<_> = generate_random_elements(n, seed).into_iter().collect(); | ||
| let Q = Element::prime_subgroup_generator(); | ||
|
|
||
| CRS::assert_dedup(&G); | ||
|
|
||
| CRS { n, G, Q } | ||
| } | ||
| // Asserts that not of the points generated are the same | ||
| fn assert_dedup(points: &[Element]) { | ||
| use std::collections::HashMap; | ||
| let mut map = HashMap::new(); | ||
| for point in points { | ||
| assert!( | ||
| map.insert(point.to_bytes(), ()).is_none(), | ||
| "crs has duplicated points" | ||
| ) | ||
| } | ||
| } | ||
| pub fn commit_lagrange_poly(&self, polynomial: &LagrangeBasis) -> Element { | ||
| slow_vartime_multiscalar_mul(polynomial.values().iter(), self.G.iter()) | ||
| } | ||
| } | ||
|
|
||
| impl std::ops::Index<usize> for CRS { | ||
| type Output = Element; | ||
|
|
||
| fn index(&self, index: usize) -> &Self::Output { | ||
| &self.G[index] | ||
| } | ||
| } | ||
|
|
||
| fn generate_random_elements(num_required_points: usize, seed: &'static [u8]) -> Vec<Element> { | ||
| use ark_ec::group::Group; | ||
| use ark_ff::PrimeField; | ||
| use bandersnatch::Fq; | ||
| use sha2::{Digest, Sha256}; | ||
|
|
||
| let choose_largest = false; | ||
|
|
||
| (0u64..) | ||
| .into_iter() | ||
| // Hash the seed + i to get a possible x value | ||
| .map(|i| { | ||
| let mut hasher = Sha256::new(); | ||
| hasher.update(seed); | ||
| hasher.update(&i.to_be_bytes()); | ||
| let bytes: Vec<u8> = hasher.finalize().to_vec(); | ||
| bytes | ||
| }) | ||
| // The Element::from_bytes method does not reduce the bytes, it expects the | ||
| // input to be in a canonical format, so we must do the reduction ourselves | ||
| .map(|hash_bytes| Fq::from_be_bytes_mod_order(&hash_bytes)) | ||
| .map(|x_coord| { | ||
| let mut bytes = [0u8; 32]; | ||
| x_coord.serialize(&mut bytes[..]).unwrap(); | ||
| // TODO: this reverse is hacky, and its because there is no way to specify the endianness in arkworks | ||
| // TODO So we reverse it here, to be interopable with the banderwagon specs which needs big endian bytes | ||
| bytes.reverse(); | ||
| bytes | ||
| }) | ||
| // Deserialise the x-cordinate to get a valid banderwagon element | ||
| .map(|bytes| Element::from_bytes(&bytes)) | ||
| .filter_map(|point| point) | ||
| .take(num_required_points) | ||
| .collect() | ||
| } | ||
|
|
||
| #[test] | ||
| fn crs_consistency() { | ||
| // TODO: update hackmd as we are now using banderwagon and the point finding strategy | ||
| // TODO is a bit different | ||
| // See: https://hackmd.io/1RcGSMQgT4uREaq1CCx_cg#Methodology | ||
| use ark_serialize::CanonicalSerialize; | ||
| use bandersnatch::Fq; | ||
| use sha2::{Digest, Sha256}; | ||
|
|
||
| let points = generate_random_elements(256, b"eth_verkle_oct_2021"); | ||
|
|
||
| let mut bytes = [0u8; 32]; | ||
| points[0].serialize(&mut bytes[..]).unwrap(); | ||
| assert_eq!( | ||
| hex::encode(&bytes), | ||
| "01587ad1336675eb912550ec2a28eb8923b824b490dd2ba82e48f14590a298a0", | ||
| "the first point is incorrect" | ||
| ); | ||
| let mut bytes = [0u8; 32]; | ||
| points[255].serialize(&mut bytes[..]).unwrap(); | ||
| assert_eq!( | ||
| hex::encode(&bytes), | ||
| "3de2be346b539395b0c0de56a5ccca54a317f1b5c80107b0802af9a62276a4d8", | ||
| "the 256th (last) point is incorrect" | ||
| ); | ||
|
|
||
| let mut hasher = Sha256::new(); | ||
| for point in &points { | ||
| let mut bytes = [0u8; 32]; | ||
| point.serialize(&mut bytes[..]).unwrap(); | ||
| hasher.update(&bytes); | ||
| } | ||
| let bytes = hasher.finalize().to_vec(); | ||
| assert_eq!( | ||
| hex::encode(&bytes), | ||
| "1fcaea10bf24f750200e06fa473c76ff0468007291fa548e2d99f09ba9256fdb", | ||
| "unexpected point encountered" | ||
| ); | ||
| } |
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