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
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
// Copyright 2024 Aleo Network Foundation
// This file is part of the snarkVM library.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use super::*;
impl<N: Network> Request<N> {
/// Returns the request for a given private key, program ID, function name, inputs, input types, and RNG, where:
/// challenge := HashToScalar(r * G, pk_sig, pr_sig, signer, \[tvk, tcm, function ID, input IDs\])
/// response := r - challenge * sk_sig
pub fn sign<R: Rng + CryptoRng>(
private_key: &PrivateKey<N>,
program_id: ProgramID<N>,
function_name: Identifier<N>,
inputs: impl ExactSizeIterator<Item = impl TryInto<Value<N>>>,
input_types: &[ValueType<N>],
root_tvk: Option<Field<N>>,
is_root: bool,
rng: &mut R,
) -> Result<Self> {
// Ensure the number of inputs matches the number of input types.
if input_types.len() != inputs.len() {
bail!(
"'{program_id}/{function_name}' expects {} inputs, but {} were provided.",
input_types.len(),
inputs.len()
)
}
// Retrieve `sk_sig`.
let sk_sig = private_key.sk_sig();
// Derive the compute key.
let compute_key = ComputeKey::try_from(private_key)?;
// Retrieve `pk_sig`.
let pk_sig = compute_key.pk_sig();
// Retrieve `pr_sig`.
let pr_sig = compute_key.pr_sig();
// Derive the view key.
let view_key = ViewKey::try_from((private_key, &compute_key))?;
// Derive `sk_tag` from the graph key.
let sk_tag = GraphKey::try_from(view_key)?.sk_tag();
// Sample a random nonce.
let nonce = Field::<N>::rand(rng);
// Compute a `r` as `HashToScalar(sk_sig || nonce)`. Note: This is the transition secret key `tsk`.
let r = N::hash_to_scalar_psd4(&[N::serial_number_domain(), sk_sig.to_field()?, nonce])?;
// Compute `g_r` as `r * G`. Note: This is the transition public key `tpk`.
let g_r = N::g_scalar_multiply(&r);
// Derive the signer from the compute key.
let signer = Address::try_from(compute_key)?;
// Compute the transition view key `tvk` as `r * signer`.
let tvk = (*signer * r).to_x_coordinate();
// Compute the transition commitment `tcm` as `Hash(tvk)`.
let tcm = N::hash_psd2(&[tvk])?;
// Compute the signer commitment `scm` as `Hash(signer || root_tvk)`.
let root_tvk = root_tvk.unwrap_or(tvk);
let scm = N::hash_psd2(&[signer.deref().to_x_coordinate(), root_tvk])?;
// Compute 'is_root' as a field element.
let is_root = if is_root { Field::<N>::one() } else { Field::<N>::zero() };
// Retrieve the network ID.
let network_id = U16::new(N::ID);
// Compute the function ID.
let function_id = compute_function_id(&network_id, &program_id, &function_name)?;
// Construct the hash input as `(r * G, pk_sig, pr_sig, signer, [tvk, tcm, function ID, input IDs])`.
let mut message = Vec::with_capacity(9 + 2 * inputs.len());
message.extend([g_r, pk_sig, pr_sig, *signer].map(|point| point.to_x_coordinate()));
message.extend([tvk, tcm, function_id, is_root]);
// Initialize a vector to store the prepared inputs.
let mut prepared_inputs = Vec::with_capacity(inputs.len());
// Initialize a vector to store the input IDs.
let mut input_ids = Vec::with_capacity(inputs.len());
// Prepare the inputs.
for (index, (input, input_type)) in inputs.zip_eq(input_types).enumerate() {
// Prepare the input.
let input = input.try_into().map_err(|_| {
anyhow!("Failed to parse input #{index} ('{input_type}') for '{program_id}/{function_name}'")
})?;
// Store the prepared input.
prepared_inputs.push(input.clone());
match input_type {
// A constant input is hashed (using `tcm`) to a field element.
ValueType::Constant(..) => {
// Ensure the input is a plaintext.
ensure!(matches!(input, Value::Plaintext(..)), "Expected a plaintext input");
// Construct the (console) input index as a field element.
let index = Field::from_u16(u16::try_from(index).or_halt_with::<N>("Input index exceeds u16"));
// Construct the preimage as `(function ID || input || tcm || index)`.
let mut preimage = Vec::new();
preimage.push(function_id);
preimage.extend(input.to_fields()?);
preimage.push(tcm);
preimage.push(index);
// Hash the input to a field element.
let input_hash = N::hash_psd8(&preimage)?;
// Add the input hash to the preimage.
message.push(input_hash);
// Add the input ID to the inputs.
input_ids.push(InputID::Constant(input_hash));
}
// A public input is hashed (using `tcm`) to a field element.
ValueType::Public(..) => {
// Ensure the input is a plaintext.
ensure!(matches!(input, Value::Plaintext(..)), "Expected a plaintext input");
// Construct the (console) input index as a field element.
let index = Field::from_u16(u16::try_from(index).or_halt_with::<N>("Input index exceeds u16"));
// Construct the preimage as `(function ID || input || tcm || index)`.
let mut preimage = Vec::new();
preimage.push(function_id);
preimage.extend(input.to_fields()?);
preimage.push(tcm);
preimage.push(index);
// Hash the input to a field element.
let input_hash = N::hash_psd8(&preimage)?;
// Add the input hash to the preimage.
message.push(input_hash);
// Add the input ID to the inputs.
input_ids.push(InputID::Public(input_hash));
}
// A private input is encrypted (using `tvk`) and hashed to a field element.
ValueType::Private(..) => {
// Ensure the input is a plaintext.
ensure!(matches!(input, Value::Plaintext(..)), "Expected a plaintext input");
// Construct the (console) input index as a field element.
let index = Field::from_u16(u16::try_from(index).or_halt_with::<N>("Input index exceeds u16"));
// Compute the input view key as `Hash(function ID || tvk || index)`.
let input_view_key = N::hash_psd4(&[function_id, tvk, index])?;
// Compute the ciphertext.
let ciphertext = match &input {
Value::Plaintext(plaintext) => plaintext.encrypt_symmetric(input_view_key)?,
// Ensure the input is a plaintext.
Value::Record(..) => bail!("Expected a plaintext input, found a record input"),
Value::Future(..) => bail!("Expected a plaintext input, found a future input"),
};
// Hash the ciphertext to a field element.
let input_hash = N::hash_psd8(&ciphertext.to_fields()?)?;
// Add the input hash to the preimage.
message.push(input_hash);
// Add the input hash to the inputs.
input_ids.push(InputID::Private(input_hash));
}
// A record input is computed to its serial number.
ValueType::Record(record_name) => {
// Retrieve the record.
let record = match &input {
Value::Record(record) => record,
// Ensure the input is a record.
Value::Plaintext(..) => bail!("Expected a record input, found a plaintext input"),
Value::Future(..) => bail!("Expected a record input, found a future input"),
};
// Ensure the record belongs to the signer.
ensure!(**record.owner() == signer, "Input record for '{program_id}' must belong to the signer");
// Compute the record commitment.
let commitment = record.to_commitment(&program_id, record_name)?;
// Compute the generator `H` as `HashToGroup(commitment)`.
let h = N::hash_to_group_psd2(&[N::serial_number_domain(), commitment])?;
// Compute `h_r` as `r * H`.
let h_r = h * r;
// Compute `gamma` as `sk_sig * H`.
let gamma = h * sk_sig;
// Compute the `serial_number` from `gamma`.
let serial_number = Record::<N, Plaintext<N>>::serial_number_from_gamma(&gamma, commitment)?;
// Compute the tag.
let tag = Record::<N, Plaintext<N>>::tag(sk_tag, commitment)?;
// Add (`H`, `r * H`, `gamma`, `tag`) to the preimage.
message.extend([h, h_r, gamma].iter().map(|point| point.to_x_coordinate()));
message.push(tag);
// Add the input ID.
input_ids.push(InputID::Record(commitment, gamma, serial_number, tag));
}
// An external record input is hashed (using `tvk`) to a field element.
ValueType::ExternalRecord(..) => {
// Ensure the input is a record.
ensure!(matches!(input, Value::Record(..)), "Expected a record input");
// Construct the (console) input index as a field element.
let index = Field::from_u16(u16::try_from(index).or_halt_with::<N>("Input index exceeds u16"));
// Construct the preimage as `(function ID || input || tvk || index)`.
let mut preimage = Vec::new();
preimage.push(function_id);
preimage.extend(input.to_fields()?);
preimage.push(tvk);
preimage.push(index);
// Hash the input to a field element.
let input_hash = N::hash_psd8(&preimage)?;
// Add the input hash to the preimage.
message.push(input_hash);
// Add the input hash to the inputs.
input_ids.push(InputID::ExternalRecord(input_hash));
}
// A future is not a valid input.
ValueType::Future(..) => bail!("A future is not a valid input"),
}
}
// Compute `challenge` as `HashToScalar(r * G, pk_sig, pr_sig, signer, [tvk, tcm, function ID, input IDs])`.
let challenge = N::hash_to_scalar_psd8(&message)?;
// Compute `response` as `r - challenge * sk_sig`.
let response = r - challenge * sk_sig;
Ok(Self {
signer,
network_id,
program_id,
function_name,
input_ids,
inputs: prepared_inputs,
signature: Signature::from((challenge, response, compute_key)),
sk_tag,
tvk,
tcm,
scm,
})
}
}