ebfull
GitHub
commit
3163e801b9
511
src/lib.rs
Normal file
511
src/lib.rs
Normal file
@ -0,0 +1,511 @@
|
||||
extern crate pairing;
|
||||
|
||||
use pairing::{Engine, Field};
|
||||
use std::ops::{Add, Sub};
|
||||
use std::fmt;
|
||||
use std::error::Error;
|
||||
|
||||
/// This represents a linear combination of some variables, with coefficients
|
||||
/// in the scalar field of a pairing-friendly elliptic curve group.
|
||||
pub struct LinearCombination<T, E: Engine>(Vec<(T, E::Fr)>);
|
||||
|
||||
impl<T, E: Engine> AsRef<[(T, E::Fr)]> for LinearCombination<T, E> {
|
||||
fn as_ref(&self) -> &[(T, E::Fr)] {
|
||||
&self.0
|
||||
}
|
||||
}
|
||||
|
||||
impl<T, E: Engine> LinearCombination<T, E> {
|
||||
pub fn zero() -> LinearCombination<T, E> {
|
||||
LinearCombination(vec![])
|
||||
}
|
||||
}
|
||||
|
||||
impl<T, E: Engine> Add<(E::Fr, T)> for LinearCombination<T, E> {
|
||||
type Output = LinearCombination<T, E>;
|
||||
|
||||
fn add(mut self, (coeff, var): (E::Fr, T)) -> LinearCombination<T, E> {
|
||||
self.0.push((var, coeff));
|
||||
|
||||
self
|
||||
}
|
||||
}
|
||||
|
||||
impl<T, E: Engine> Sub<(E::Fr, T)> for LinearCombination<T, E> {
|
||||
type Output = LinearCombination<T, E>;
|
||||
|
||||
fn sub(self, (mut coeff, var): (E::Fr, T)) -> LinearCombination<T, E> {
|
||||
coeff.negate();
|
||||
|
||||
self + (coeff, var)
|
||||
}
|
||||
}
|
||||
|
||||
impl<T, E: Engine> Add<T> for LinearCombination<T, E> {
|
||||
type Output = LinearCombination<T, E>;
|
||||
|
||||
fn add(self, other: T) -> LinearCombination<T, E> {
|
||||
self + (E::Fr::one(), other)
|
||||
}
|
||||
}
|
||||
|
||||
impl<T, E: Engine> Sub<T> for LinearCombination<T, E> {
|
||||
type Output = LinearCombination<T, E>;
|
||||
|
||||
fn sub(self, other: T) -> LinearCombination<T, E> {
|
||||
self - (E::Fr::one(), other)
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_lc() {
|
||||
use pairing::bls12_381::{Bls12, Fr};
|
||||
|
||||
let a = LinearCombination::<usize, Bls12>::zero() + 0usize + 1usize + 2usize - 3usize;
|
||||
|
||||
let mut negone = Fr::one();
|
||||
negone.negate();
|
||||
|
||||
assert_eq!(a.0, vec![(0usize, Fr::one()), (1usize, Fr::one()), (2usize, Fr::one()), (3usize, negone)]);
|
||||
}
|
||||
|
||||
/// This is an error that could occur during circuit synthesis contexts,
|
||||
/// such as CRS generation, proving or verification.
|
||||
#[derive(Debug)]
|
||||
pub enum SynthesisError {
|
||||
AssignmentMissing
|
||||
}
|
||||
|
||||
impl Error for SynthesisError {
|
||||
fn description(&self) -> &str {
|
||||
match *self {
|
||||
SynthesisError::AssignmentMissing => "an assignment for a variable could not be computed"
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl fmt::Display for SynthesisError {
|
||||
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
|
||||
write!(f, "{}", self.description())
|
||||
}
|
||||
}
|
||||
|
||||
pub trait ConstraintSystem<E: Engine>: Sized {
|
||||
type Variable: Sized + Copy + Clone;
|
||||
|
||||
/// Represents the type of the "root" of this constraint system
|
||||
/// so that nested namespaces can minimize indirection.
|
||||
type Root: ConstraintSystem<E, Variable=Self::Variable>;
|
||||
|
||||
/// Return the "one" input variable
|
||||
fn one(&self) -> Self::Variable;
|
||||
|
||||
/// Allocate a private variable in the constraint system. The provided function is used to
|
||||
/// determine the assignment of the variable. The given `annotation` function is invoked
|
||||
/// in testing contexts in order to derive a unique name for this variable in the current
|
||||
/// namespace.
|
||||
fn alloc<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>;
|
||||
|
||||
/// Enforce that `A` * `B` = `C`. The `annotation` function is invoked in testing contexts
|
||||
/// in order to derive a unique name for the constraint in the current namespace.
|
||||
fn enforce<A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
a: LinearCombination<Self::Variable, E>,
|
||||
b: LinearCombination<Self::Variable, E>,
|
||||
c: LinearCombination<Self::Variable, E>
|
||||
)
|
||||
where A: FnOnce() -> AR, AR: Into<String>;
|
||||
|
||||
/// Create a new (sub)namespace and enter into it. Not intended
|
||||
/// for downstream use; use `namespace` instead.
|
||||
fn push_namespace<NR, N>(&mut self, name_fn: N)
|
||||
where NR: Into<String>, N: FnOnce() -> NR;
|
||||
|
||||
/// Exit out of the existing namespace. Not intended for
|
||||
/// downstream use; use `namespace` instead.
|
||||
fn pop_namespace(&mut self);
|
||||
|
||||
/// Gets the "root" constraint system, bypassing the namespacing.
|
||||
/// Not intended for downstream use; use `namespace` instead.
|
||||
fn get_root(&mut self) -> &mut Self::Root;
|
||||
|
||||
/// Begin a namespace for this constraint system.
|
||||
fn namespace<'a, NR, N>(
|
||||
&'a mut self,
|
||||
name_fn: N
|
||||
) -> Namespace<'a, E, Self::Root>
|
||||
where NR: Into<String>, N: FnOnce() -> NR
|
||||
{
|
||||
self.get_root().push_namespace(name_fn);
|
||||
|
||||
Namespace(self.get_root(), PhantomData)
|
||||
}
|
||||
}
|
||||
|
||||
pub trait PublicConstraintSystem<E: Engine>: ConstraintSystem<E>
|
||||
{
|
||||
/// Represents the type of the "root" of this constraint system
|
||||
/// so that nested namespaces can minimize indirection.
|
||||
type PublicRoot: PublicConstraintSystem<E, Variable=Self::Variable>;
|
||||
|
||||
/// Allocate a public variable in the constraint system. The provided function is used to
|
||||
/// determine the assignment of the variable.
|
||||
fn alloc_input<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>;
|
||||
|
||||
/// Gets the "root" constraint system, bypassing the namespacing.
|
||||
/// Not intended for downstream use; use `namespace` instead.
|
||||
fn get_public_root(&mut self) -> &mut Self::PublicRoot;
|
||||
|
||||
/// Begin a namespace for this constraint system.
|
||||
fn namespace_public<'a, NR, N>(
|
||||
&'a mut self,
|
||||
name_fn: N
|
||||
) -> Namespace<'a, E, Self::PublicRoot>
|
||||
where NR: Into<String>, N: FnOnce() -> NR
|
||||
{
|
||||
self.get_root().push_namespace(name_fn);
|
||||
|
||||
Namespace(self.get_public_root(), PhantomData)
|
||||
}
|
||||
}
|
||||
|
||||
use std::marker::PhantomData;
|
||||
|
||||
/// This is a "namespaced" constraint system which borrows a constraint system (pushing
|
||||
/// a namespace context) and, when dropped, pops out of the namespace context.
|
||||
pub struct Namespace<'a, E: Engine, CS: ConstraintSystem<E> + 'a>(&'a mut CS, PhantomData<E>);
|
||||
|
||||
impl<'cs, E: Engine, CS: PublicConstraintSystem<E>> PublicConstraintSystem<E> for Namespace<'cs, E, CS> {
|
||||
type PublicRoot = CS::PublicRoot;
|
||||
|
||||
fn alloc_input<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
self.0.alloc_input(annotation, f)
|
||||
}
|
||||
|
||||
fn get_public_root(&mut self) -> &mut Self::PublicRoot
|
||||
{
|
||||
self.0.get_public_root()
|
||||
}
|
||||
}
|
||||
|
||||
impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for Namespace<'cs, E, CS> {
|
||||
type Variable = CS::Variable;
|
||||
type Root = CS::Root;
|
||||
|
||||
fn one(&self) -> Self::Variable {
|
||||
self.0.one()
|
||||
}
|
||||
|
||||
fn alloc<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
self.0.alloc(annotation, f)
|
||||
}
|
||||
|
||||
fn enforce<A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
a: LinearCombination<Self::Variable, E>,
|
||||
b: LinearCombination<Self::Variable, E>,
|
||||
c: LinearCombination<Self::Variable, E>
|
||||
)
|
||||
where A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
self.0.enforce(annotation, a, b, c)
|
||||
}
|
||||
|
||||
// Downstream users who use `namespace` will never interact with these
|
||||
// functions and they will never be invoked because the namespace is
|
||||
// never a root constraint system.
|
||||
|
||||
fn push_namespace<NR, N>(&mut self, _: N)
|
||||
where NR: Into<String>, N: FnOnce() -> NR
|
||||
{
|
||||
panic!("only the root's push_namespace should be called");
|
||||
}
|
||||
|
||||
fn pop_namespace(&mut self)
|
||||
{
|
||||
panic!("only the root's pop_namespace should be called");
|
||||
}
|
||||
|
||||
fn get_root(&mut self) -> &mut Self::Root
|
||||
{
|
||||
self.0.get_root()
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, E: Engine, CS: ConstraintSystem<E>> Drop for Namespace<'a, E, CS> {
|
||||
fn drop(&mut self) {
|
||||
self.get_root().pop_namespace()
|
||||
}
|
||||
}
|
||||
|
||||
/// Convenience implementation of PublicConstraintSystem<E> for mutable references to
|
||||
/// public constraint systems.
|
||||
impl<'cs, E: Engine, CS: PublicConstraintSystem<E>> PublicConstraintSystem<E> for &'cs mut CS {
|
||||
type PublicRoot = CS::PublicRoot;
|
||||
|
||||
fn alloc_input<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
(**self).alloc_input(annotation, f)
|
||||
}
|
||||
|
||||
fn get_public_root(&mut self) -> &mut Self::PublicRoot
|
||||
{
|
||||
(**self).get_public_root()
|
||||
}
|
||||
}
|
||||
|
||||
/// Convenience implementation of ConstraintSystem<E> for mutable references to
|
||||
/// constraint systems.
|
||||
impl<'cs, E: Engine, CS: ConstraintSystem<E>> ConstraintSystem<E> for &'cs mut CS {
|
||||
type Variable = CS::Variable;
|
||||
type Root = CS::Root;
|
||||
|
||||
fn one(&self) -> Self::Variable {
|
||||
(**self).one()
|
||||
}
|
||||
|
||||
fn alloc<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
(**self).alloc(annotation, f)
|
||||
}
|
||||
|
||||
fn enforce<A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
a: LinearCombination<Self::Variable, E>,
|
||||
b: LinearCombination<Self::Variable, E>,
|
||||
c: LinearCombination<Self::Variable, E>
|
||||
)
|
||||
where A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
(**self).enforce(annotation, a, b, c)
|
||||
}
|
||||
|
||||
fn push_namespace<NR, N>(&mut self, name_fn: N)
|
||||
where NR: Into<String>, N: FnOnce() -> NR
|
||||
{
|
||||
(**self).push_namespace(name_fn)
|
||||
}
|
||||
|
||||
fn pop_namespace(&mut self)
|
||||
{
|
||||
(**self).pop_namespace()
|
||||
}
|
||||
|
||||
fn get_root(&mut self) -> &mut Self::Root
|
||||
{
|
||||
(**self).get_root()
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_cs() {
|
||||
use pairing::bls12_381::{Bls12, Fr};
|
||||
|
||||
#[derive(PartialEq, Copy, Clone)]
|
||||
enum Var {
|
||||
Input(usize),
|
||||
Aux(usize)
|
||||
}
|
||||
|
||||
struct MySillyConstraintSystem<E: Engine> {
|
||||
inputs: Vec<(E::Fr, String)>,
|
||||
aux: Vec<(E::Fr, String)>,
|
||||
constraints: Vec<(LinearCombination<Var, E>, LinearCombination<Var, E>, LinearCombination<Var, E>, String)>,
|
||||
current_namespace: Vec<String>
|
||||
}
|
||||
|
||||
fn compute_path(ns: &[String], this: String) -> String {
|
||||
let mut name = String::new();
|
||||
|
||||
let mut needs_separation = false;
|
||||
for ns in ns.iter().chain(Some(&this).into_iter())
|
||||
{
|
||||
if needs_separation {
|
||||
name += "/";
|
||||
}
|
||||
|
||||
name += ns;
|
||||
needs_separation = true;
|
||||
}
|
||||
|
||||
name
|
||||
}
|
||||
|
||||
impl<E: Engine> PublicConstraintSystem<E> for MySillyConstraintSystem<E> {
|
||||
type PublicRoot = Self;
|
||||
|
||||
fn alloc_input<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
let index = self.inputs.len();
|
||||
let path = compute_path(&self.current_namespace, annotation().into());
|
||||
self.inputs.push((f()?, path));
|
||||
|
||||
Ok(Var::Input(index))
|
||||
}
|
||||
|
||||
fn get_public_root(&mut self) -> &mut Self::PublicRoot
|
||||
{
|
||||
self
|
||||
}
|
||||
}
|
||||
|
||||
impl<E: Engine> ConstraintSystem<E> for MySillyConstraintSystem<E> {
|
||||
type Variable = Var;
|
||||
type Root = Self;
|
||||
|
||||
fn one(&self) -> Self::Variable {
|
||||
Var::Input(0)
|
||||
}
|
||||
|
||||
fn alloc<F, A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
f: F
|
||||
) -> Result<Self::Variable, SynthesisError>
|
||||
where F: FnOnce() -> Result<E::Fr, SynthesisError>, A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
let index = self.aux.len();
|
||||
let path = compute_path(&self.current_namespace, annotation().into());
|
||||
self.aux.push((f()?, path));
|
||||
|
||||
Ok(Var::Aux(index))
|
||||
}
|
||||
|
||||
fn enforce<A, AR>(
|
||||
&mut self,
|
||||
annotation: A,
|
||||
a: LinearCombination<Self::Variable, E>,
|
||||
b: LinearCombination<Self::Variable, E>,
|
||||
c: LinearCombination<Self::Variable, E>
|
||||
)
|
||||
where A: FnOnce() -> AR, AR: Into<String>
|
||||
{
|
||||
let path = compute_path(&self.current_namespace, annotation().into());
|
||||
|
||||
self.constraints.push((a, b, c, path));
|
||||
}
|
||||
|
||||
fn push_namespace<NR, N>(&mut self, name_fn: N)
|
||||
where NR: Into<String>, N: FnOnce() -> NR
|
||||
{
|
||||
self.current_namespace.push(name_fn().into());
|
||||
}
|
||||
|
||||
fn pop_namespace(&mut self)
|
||||
{
|
||||
self.current_namespace.pop();
|
||||
}
|
||||
|
||||
fn get_root(&mut self) -> &mut Self::Root
|
||||
{
|
||||
self
|
||||
}
|
||||
}
|
||||
|
||||
fn do_stuff_with_pcs<E: Engine, CS: PublicConstraintSystem<E>>(mut cs: CS, one_more: bool)
|
||||
{
|
||||
cs.alloc_input(|| "something", || Ok(E::Fr::zero())).unwrap();
|
||||
|
||||
if one_more {
|
||||
do_stuff_with_pcs(cs.namespace_public(|| "cool namespace"), false);
|
||||
}
|
||||
}
|
||||
|
||||
let mut cs = MySillyConstraintSystem::<Bls12> {
|
||||
inputs: vec![(Fr::one(), "ONE".into())],
|
||||
aux: vec![],
|
||||
constraints: vec![],
|
||||
current_namespace: vec![]
|
||||
};
|
||||
cs.alloc(|| "something", || Ok(Fr::zero())).unwrap();
|
||||
assert_eq!(cs.inputs, vec![(Fr::one(), "ONE".into())]);
|
||||
assert_eq!(cs.aux, vec![(Fr::zero(), "something".into())]);
|
||||
{
|
||||
let mut cs = cs.namespace(|| "woohoo");
|
||||
|
||||
cs.alloc(|| "whatever", || Ok(Fr::one())).unwrap();
|
||||
cs.alloc(|| "you", || Ok(Fr::zero())).unwrap();
|
||||
cs.alloc(|| "say", || Ok(Fr::one())).unwrap();
|
||||
|
||||
{
|
||||
let mut cs = cs.namespace(|| "hehe");
|
||||
|
||||
let v1 = cs.alloc(|| "hehe, indeed", || Ok(Fr::one())).unwrap();
|
||||
let v2 = cs.alloc_input(|| "works lol", || Ok(Fr::zero())).unwrap();
|
||||
|
||||
let one = cs.one();
|
||||
|
||||
cs.enforce(
|
||||
|| "great constraint",
|
||||
LinearCombination::zero() + v1,
|
||||
LinearCombination::zero() + one,
|
||||
LinearCombination::zero() + v2
|
||||
);
|
||||
}
|
||||
}
|
||||
assert_eq!(cs.aux, vec![
|
||||
(Fr::zero(), "something".into()),
|
||||
(Fr::one(), "woohoo/whatever".into()),
|
||||
(Fr::zero(), "woohoo/you".into()),
|
||||
(Fr::one(), "woohoo/say".into()),
|
||||
(Fr::one(), "woohoo/hehe/hehe, indeed".into()),
|
||||
]);
|
||||
assert_eq!(cs.inputs, vec![
|
||||
(Fr::one(), "ONE".into()),
|
||||
(Fr::zero(), "woohoo/hehe/works lol".into()),
|
||||
]);
|
||||
assert!(cs.constraints.len() == 1);
|
||||
assert!((cs.constraints[0].0).0 == vec![(Var::Aux(4), Fr::one())]);
|
||||
assert!((cs.constraints[0].1).0 == vec![(Var::Input(0), Fr::one())]);
|
||||
assert!((cs.constraints[0].2).0 == vec![(Var::Input(1), Fr::one())]);
|
||||
assert!(cs.constraints[0].3 == "woohoo/hehe/great constraint");
|
||||
|
||||
do_stuff_with_pcs(cs.namespace(|| "namey"), true);
|
||||
|
||||
assert_eq!(cs.inputs, vec![
|
||||
(Fr::one(), "ONE".into()),
|
||||
(Fr::zero(), "woohoo/hehe/works lol".into()),
|
||||
(Fr::zero(), "namey/something".into()),
|
||||
(Fr::zero(), "namey/cool namespace/something".into()),
|
||||
]);
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user