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SinsemillaChip::configure(): Introduce closures for Y_A and x_r 

These expressions are derived multiple times in the gates.

Co-authored-by: Jack Grigg <jack@electriccoin.co>
This commit is contained in:
therealyingtong 2021-06-20 10:43:24 +08:00
parent 9072ed437d
commit 031bb0bc87
1 changed files with 27 additions and 39 deletions
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66
src/circuit/gadget/sinsemilla/chip.rs
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@ -16,7 +16,10 @@ use ff::PrimeField;
use halo2::{
arithmetic::{CurveAffine, FieldExt},
circuit::{Chip, Layouter},
plonk::{Advice, Column, ConstraintSystem, Error, Expression, Fixed, Permutation, Selector},
plonk::{
Advice, Column, ConstraintSystem, Error, Expression, Fixed, Permutation, Selector,
VirtualCells,
},
poly::Rotation,
};
use pasta_curves::pallas;
@ -126,25 +129,32 @@ impl SinsemillaChip {
// Set up lookup argument
GeneratorTableConfig::configure(meta, config.clone());
// Constant expressions
let two = Expression::Constant(pallas::Base::from_u64(2));
// Closures for expressions that are derived multiple times
// x_r = lambda_1^2 - x_a - x_p
let x_r = |meta: &mut VirtualCells<pallas::Base>, rotation| {
let x_a = meta.query_advice(config.x_a, rotation);
let x_p = meta.query_advice(config.x_p, rotation);
let lambda_1 = meta.query_advice(config.lambda_1, rotation);
lambda_1.square() - x_a - x_p
};
// Y_A = (lambda_1 + lambda_2) * (x_a - x_r)
let Y_A = |meta: &mut VirtualCells<pallas::Base>, rotation| {
let x_a = meta.query_advice(config.x_a, rotation);
let lambda_1 = meta.query_advice(config.lambda_1, rotation);
let lambda_2 = meta.query_advice(config.lambda_2, rotation);
(lambda_1 + lambda_2) * (x_a - x_r(meta, rotation))
};
// Check that the initial x_A, x_P, lambda_1, lambda_2 are consistent with y_Q.
meta.create_gate("Initial y_Q", |meta| {
let fixed_y_q = meta.query_fixed(config.fixed_y_q, Rotation::cur());
// Y_A = (lambda_1 + lambda_2) * (x_a - x_r)
let Y_A = {
let lambda_1 = meta.query_advice(config.lambda_1, Rotation::cur());
let lambda_2 = meta.query_advice(config.lambda_2, Rotation::cur());
let x_a = meta.query_advice(config.x_a, Rotation::cur());
// x_r = lambda_1^2 - x_a - x_p
let x_r = {
let x_p = meta.query_advice(config.x_p, Rotation::cur());
lambda_1.clone().square() - x_a.clone() - x_p
};
(lambda_1 + lambda_2) * (x_a - x_r)
};
let Y_A = Y_A(meta, Rotation::cur());
// fixed_y_q * (2 * fixed_y_q - Y_{A,0}) = 0
vec![fixed_y_q.clone() * (two.clone() * fixed_y_q - Y_A)]
@ -152,16 +162,12 @@ impl SinsemillaChip {
meta.create_gate("Secant line", |meta| {
let q_s1 = meta.query_selector(config.q_sinsemilla1);
let lambda_1 = meta.query_advice(config.lambda_1, Rotation::cur());
let lambda_2 = meta.query_advice(config.lambda_2, Rotation::cur());
let x_a_cur = meta.query_advice(config.x_a, Rotation::cur());
let x_a_next = meta.query_advice(config.x_a, Rotation::next());
// x_r = lambda_1^2 - x_a_cur - x_p
let x_r = {
let x_p = meta.query_advice(config.x_p, Rotation::cur());
lambda_1.square() - x_a_cur.clone() - x_p
};
let x_r = x_r(meta, Rotation::cur());
// lambda2^2 - (x_a_next + x_r + x_a_cur) = 0
let secant_line = lambda_2.square() - (x_a_next + x_r + x_a_cur);
@ -178,32 +184,14 @@ impl SinsemillaChip {
};
let x_a_cur = meta.query_advice(config.x_a, Rotation::cur());
let x_a_next = meta.query_advice(config.x_a, Rotation::next());
let lambda_1_cur = meta.query_advice(config.lambda_1, Rotation::cur());
let lambda_2_cur = meta.query_advice(config.lambda_2, Rotation::cur());
let lambda_1_next = meta.query_advice(config.lambda_1, Rotation::next());
let lambda_2_next = meta.query_advice(config.lambda_2, Rotation::next());
// Y_A = (lambda_1 + lambda_2) * (x_a - x_r)
let Y_A_cur = {
// x_r = lambda_1^2 - x_a - x_p
let x_r = {
let x_p = meta.query_advice(config.x_p, Rotation::cur());
lambda_1_cur.clone().square() - x_a_cur.clone() - x_p
};
(lambda_1_cur + lambda_2_cur.clone()) * (x_a_cur.clone() - x_r)
};
let Y_A_cur = Y_A(meta, Rotation::cur());
// Y_A = (lambda_1 + lambda_2) * (x_a - x_r)
let Y_A_next = {
// x_r = lambda_1^2 - x_a - x_p
let x_r = {
let x_p = meta.query_advice(config.x_p, Rotation::next());
lambda_1_next.clone().square() - x_a_next.clone() - x_p
};
(lambda_1_next.clone() + lambda_2_next) * (x_a_next.clone() - x_r)
};
let Y_A_next = Y_A(meta, Rotation::next());
// lhs = 4 * lambda_2_cur * (x_a_cur - x_a_next)
let lhs = lambda_2_cur * pallas::Base::from_u64(4) * (x_a_cur - x_a_next);