1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
use crate::{
bits::Boolean,
integers::uint::UInt8,
traits::{
algorithms::{CRHGadget, MaskedCRHGadget},
alloc::AllocGadget,
curves::CurveGadget,
integers::Integer,
},
};
use snarkvm_algorithms::crh::PedersenCRH;
use snarkvm_curves::ProjectiveCurve;
use snarkvm_fields::PrimeField;
use snarkvm_r1cs::{errors::SynthesisError, ConstraintSystem};
use std::{borrow::Borrow, marker::PhantomData};
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct PedersenCRHGadget<
G: ProjectiveCurve,
F: PrimeField,
GG: CurveGadget<G, F>,
const NUM_WINDOWS: usize,
const WINDOW_SIZE: usize,
> {
pub(crate) crh: PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>,
_group: PhantomData<GG>,
_engine: PhantomData<F>,
}
impl<G: ProjectiveCurve, F: PrimeField, GG: CurveGadget<G, F>, const NUM_WINDOWS: usize, const WINDOW_SIZE: usize>
AllocGadget<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>, F> for PedersenCRHGadget<G, F, GG, NUM_WINDOWS, WINDOW_SIZE>
{
fn alloc_constant<
Fn: FnOnce() -> Result<T, SynthesisError>,
T: Borrow<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>>,
CS: ConstraintSystem<F>,
>(
_cs: CS,
value_gen: Fn,
) -> Result<Self, SynthesisError> {
Ok(Self {
crh: value_gen()?.borrow().clone(),
_group: PhantomData,
_engine: PhantomData,
})
}
fn alloc<
Fn: FnOnce() -> Result<T, SynthesisError>,
T: Borrow<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>>,
CS: ConstraintSystem<F>,
>(
_cs: CS,
_value_gen: Fn,
) -> Result<Self, SynthesisError> {
unimplemented!()
}
fn alloc_input<
Fn: FnOnce() -> Result<T, SynthesisError>,
T: Borrow<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>>,
CS: ConstraintSystem<F>,
>(
_cs: CS,
_value_gen: Fn,
) -> Result<Self, SynthesisError> {
unimplemented!()
}
}
impl<F: PrimeField, G: ProjectiveCurve, GG: CurveGadget<G, F>, const NUM_WINDOWS: usize, const WINDOW_SIZE: usize>
CRHGadget<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>, F> for PedersenCRHGadget<G, F, GG, NUM_WINDOWS, WINDOW_SIZE>
{
type OutputGadget = GG;
fn check_evaluation_gadget_on_bits<CS: ConstraintSystem<F>>(
&self,
cs: CS,
input: Vec<Boolean>,
) -> Result<Self::OutputGadget, SynthesisError> {
assert!(input.len() <= WINDOW_SIZE * NUM_WINDOWS);
assert_eq!(self.crh.bases.len(), NUM_WINDOWS);
let input_in_bits = pad_input::<NUM_WINDOWS, WINDOW_SIZE>(input);
GG::multi_scalar_multiplication(cs, &self.crh.bases, input_in_bits.chunks(WINDOW_SIZE))
}
}
fn pad_input<const NUM_WINDOWS: usize, const WINDOW_SIZE: usize>(input: Vec<Boolean>) -> Vec<Boolean> {
let mut padded_input = input;
padded_input.resize(WINDOW_SIZE * NUM_WINDOWS, Boolean::Constant(false));
padded_input
}
fn pad_input_and_bitify<const NUM_WINDOWS: usize, const WINDOW_SIZE: usize>(input: Vec<UInt8>) -> Vec<Boolean> {
let mut padded_input = input;
padded_input.resize(WINDOW_SIZE * NUM_WINDOWS / 8, UInt8::constant(0u8));
assert_eq!(padded_input.len() * 8, WINDOW_SIZE * NUM_WINDOWS);
padded_input.into_iter().flat_map(|byte| byte.to_bits_le()).collect()
}
impl<F: PrimeField, G: ProjectiveCurve, GG: CurveGadget<G, F>, const NUM_WINDOWS: usize, const WINDOW_SIZE: usize>
MaskedCRHGadget<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>, F>
for PedersenCRHGadget<G, F, GG, NUM_WINDOWS, WINDOW_SIZE>
{
type MaskParametersGadget = Self;
fn check_evaluation_gadget_masked<CS: ConstraintSystem<F>>(
&self,
mut cs: CS,
input: Vec<UInt8>,
mask_parameters: &Self::MaskParametersGadget,
mask: Vec<UInt8>,
) -> Result<Self::OutputGadget, SynthesisError> {
if input.len() != mask.len() * 2 {
return Err(SynthesisError::Unsatisfiable);
}
let mask = <Self as MaskedCRHGadget<PedersenCRH<G, NUM_WINDOWS, WINDOW_SIZE>, F>>::extend_mask(
cs.ns(|| "extend mask"),
&mask,
)?;
let mask_hash = self.check_evaluation_gadget(cs.ns(|| "evaluate mask"), mask.clone())?;
let mask_input_in_bits = pad_input_and_bitify::<NUM_WINDOWS, WINDOW_SIZE>(mask.clone());
let mask_symmetric_hash = GG::symmetric_multi_scalar_multiplication(
cs.ns(|| "evaluate mask with mask bases"),
&mask_parameters.crh.bases,
mask_input_in_bits.chunks(WINDOW_SIZE),
)?;
assert_eq!(self.crh.bases.len(), NUM_WINDOWS);
let input_in_bits = pad_input_and_bitify::<NUM_WINDOWS, WINDOW_SIZE>(input);
let mask_in_bits = pad_input_and_bitify::<NUM_WINDOWS, WINDOW_SIZE>(mask);
let masked_output = GG::masked_multi_scalar_multiplication(
cs.ns(|| "multiscalar multiplication"),
&self.crh.bases,
input_in_bits.chunks(WINDOW_SIZE),
&mask_parameters.crh.bases,
mask_in_bits.chunks(WINDOW_SIZE),
)?;
masked_output
.add(cs.ns(|| "remove mask"), &mask_hash)?
.add(cs.ns(|| "remove mask with mask bases"), &mask_symmetric_hash)
}
}