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chore: add SchnorrSignature struct #170

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chore: add SchnorrSignature struct #170

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2 changes: 1 addition & 1 deletion src/acvm_interop/pwg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ impl PartialWitnessGenerator for Barretenberg {
message.push(msg_i);
}

let valid_signature = self.verify_signature(pub_key, signature, &message);
let valid_signature = self.verify_signature(pub_key, signature.into(), &message);
if !valid_signature {
dbg!("signature has failed to verify");
}
Expand Down
71 changes: 38 additions & 33 deletions src/schnorr.rs
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Original file line number Diff line number Diff line change
@@ -1,41 +1,51 @@
use crate::FIELD_BYTES;

use super::Barretenberg;

pub(crate) struct SchnorrSignature {
s: [u8; FIELD_BYTES],
e: [u8; FIELD_BYTES],
}

impl From<[u8; 2 * FIELD_BYTES]> for SchnorrSignature {
fn from(value: [u8; 2 * FIELD_BYTES]) -> Self {
let (sig_s, sig_e) = value.split_at(FIELD_BYTES);

// These cannot panic as we're just bisecting the array.
let s: [u8; FIELD_BYTES] = sig_s.try_into().unwrap();
let e: [u8; FIELD_BYTES] = sig_e.try_into().unwrap();
SchnorrSignature { s, e }
}
}

pub(crate) trait SchnorrSig {
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> [u8; 64];
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> SchnorrSignature;
fn construct_public_key(&self, private_key: [u8; 32]) -> [u8; 64];
fn verify_signature(&self, pub_key: [u8; 64], sig: [u8; 64], message: &[u8]) -> bool;
fn verify_signature(&self, pub_key: [u8; 64], sig: SchnorrSignature, message: &[u8]) -> bool;
}

#[cfg(feature = "native")]
impl SchnorrSig for Barretenberg {
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> [u8; 64] {
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> SchnorrSignature {
let (sig_s, sig_e) = barretenberg_sys::schnorr::construct_signature(message, private_key);

let sig_bytes: [u8; 64] = [sig_s, sig_e].concat().try_into().unwrap();
sig_bytes
SchnorrSignature { s: sig_s, e: sig_e }
}

fn construct_public_key(&self, private_key: [u8; 32]) -> [u8; 64] {
barretenberg_sys::schnorr::construct_public_key(&private_key)
}

fn verify_signature(&self, pub_key: [u8; 64], sig: [u8; 64], message: &[u8]) -> bool {
let (sig_s, sig_e) = sig.split_at(32);

let sig_s: [u8; 32] = sig_s.try_into().unwrap();
let sig_e: [u8; 32] = sig_e.try_into().unwrap();

barretenberg_sys::schnorr::verify_signature(pub_key, sig_s, sig_e, message)

// Note, currently for Barretenberg plonk, if the signature fails
// then the whole circuit fails.
fn verify_signature(&self, pub_key: [u8; 64], sig: SchnorrSignature, message: &[u8]) -> bool {
// Note, currently for Barretenberg plonk, if the signature fails then the whole circuit fails.
barretenberg_sys::schnorr::verify_signature(pub_key, sig.s, sig.e, message)
}
}

#[cfg(not(feature = "native"))]
impl SchnorrSig for Barretenberg {
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> [u8; 64] {
use super::{wasm::WASM_SCRATCH_BYTES, FIELD_BYTES};
fn construct_signature(&self, message: &[u8], private_key: [u8; 32]) -> SchnorrSignature {
use super::wasm::WASM_SCRATCH_BYTES;

let sig_s_ptr: usize = 0;
let sig_e_ptr: usize = sig_s_ptr + FIELD_BYTES;
Expand All @@ -59,17 +69,14 @@ impl SchnorrSig for Barretenberg {
],
);

let sig_s: [u8; FIELD_BYTES] = self.read_memory(sig_s_ptr);
let sig_e: [u8; FIELD_BYTES] = self.read_memory(sig_e_ptr);

let sig_bytes: [u8; 64] = [sig_s, sig_e].concat().try_into().unwrap();
sig_bytes
SchnorrSignature {
s: self.read_memory(sig_s_ptr),
e: self.read_memory(sig_e_ptr),
}
}

#[allow(dead_code)]
fn construct_public_key(&self, private_key: [u8; 32]) -> [u8; 64] {
use super::FIELD_BYTES;

let private_key_ptr: usize = 0;
let result_ptr: usize = private_key_ptr + FIELD_BYTES;

Expand All @@ -83,23 +90,21 @@ impl SchnorrSig for Barretenberg {
self.read_memory(result_ptr)
}

fn verify_signature(&self, pub_key: [u8; 64], sig: [u8; 64], message: &[u8]) -> bool {
use super::{wasm::WASM_SCRATCH_BYTES, FIELD_BYTES};

let (sig_s, sig_e) = sig.split_at(FIELD_BYTES);
fn verify_signature(&self, pub_key: [u8; 64], sig: SchnorrSignature, message: &[u8]) -> bool {
use super::wasm::WASM_SCRATCH_BYTES;

let public_key_ptr: usize = 0;
let sig_s_ptr: usize = public_key_ptr + pub_key.len();
let sig_e_ptr: usize = sig_s_ptr + sig_s.len();
let message_ptr: usize = sig_e_ptr + sig_e.len();
let sig_e_ptr: usize = sig_s_ptr + sig.s.len();
let message_ptr: usize = sig_e_ptr + sig.e.len();
assert!(
message_ptr + message.len() < WASM_SCRATCH_BYTES,
"Message overran wasm scratch space"
);

self.transfer_to_heap(&pub_key, public_key_ptr);
self.transfer_to_heap(sig_s, sig_s_ptr);
self.transfer_to_heap(sig_e, sig_e_ptr);
self.transfer_to_heap(&sig.s, sig_s_ptr);
self.transfer_to_heap(&sig.e, sig_e_ptr);
self.transfer_to_heap(message, message_ptr);

let wasm_value = self.call_multiple(
Expand Down Expand Up @@ -144,7 +149,7 @@ fn basic_interop() {
// Should fail, since the signature is not valid
let private_key = [2; 32];
let message = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
let signature = [1; 64];
let signature = SchnorrSignature::from([1; 64]);

let public_key = barretenberg.construct_public_key(private_key);
let valid_signature = barretenberg.verify_signature(public_key, signature, &message);
Expand Down