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// Copyright (c) 2019-2026 Provable Inc.
// 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, is_dynamic, and RNG, where:
/// challenge := HashToScalar(r * G, pk_sig, pr_sig, signer, \[tvk, tcm, function ID, is_root, program checksum?, input IDs\])
/// response := r - challenge * sk_sig
/// The program checksum must be provided if the program has a constructor and should not be provided otherwise.
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,
program_checksum: Option<Field<N>>,
is_dynamic: 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, is_root, program checksum?, 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]);
// Add the program checksum to the hash input if it was provided.
if let Some(program_checksum) = program_checksum {
message.push(program_checksum);
}
// 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}'")
})?;
// If the function expects a dynamic record but a record was provided, convert it.
let input = match (&input, input_type) {
(Value::Record(record), ValueType::DynamicRecord) => {
Value::DynamicRecord(DynamicRecord::from_record(record)?)
}
_ => input,
};
// Store the prepared input.
prepared_inputs.push(input.clone());
// Convert index to u16.
let index = u16::try_from(index).map_err(|_| anyhow!("Input index exceeds u16"))?;
match input_type {
// A constant input is hashed (using `tcm`) to a field element.
ValueType::Constant(..) => {
let input_id = InputID::constant(function_id, &input, tcm, index)?;
message.push(*input_id.id());
input_ids.push(input_id);
}
// A public input is hashed (using `tcm`) to a field element.
ValueType::Public(..) => {
let input_id = InputID::public(function_id, &input, tcm, index)?;
message.push(*input_id.id());
input_ids.push(input_id);
}
// A private input is encrypted (using `tvk`) and hashed to a field element.
ValueType::Private(..) => {
let input_id = InputID::private(function_id, &input, tvk, index)?;
message.push(*input_id.id());
input_ids.push(input_id);
}
// A record input is computed to its serial number.
ValueType::Record(record_name) => {
// Compute the input ID (commitment, gamma, record view key, serial number, tag).
let input_id =
InputID::record(&program_id, record_name, &input, &signer, &view_key, &sk_sig, sk_tag)?;
// Extract the commitment, gamma, and tag for the message.
let (commitment, gamma, tag) = match &input_id {
InputID::Record(c, g, _, _, t) => (*c, *g, *t),
// InputID::record always returns the Record variant.
_ => unreachable!(),
};
// 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;
// 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);
input_ids.push(input_id);
}
// An external record input is hashed (using `tvk`) to a field element.
ValueType::ExternalRecord(..) => {
let input_id = InputID::external_record(function_id, &input, tvk, index)?;
message.push(*input_id.id());
input_ids.push(input_id);
}
// A future is not a valid input.
ValueType::Future(..) => bail!("A future is not a valid input"),
// A dynamic record input is hashed (using `tvk`) to a field element.
ValueType::DynamicRecord => {
let input_id = InputID::dynamic_record(function_id, &input, tvk, index)?;
message.push(*input_id.id());
input_ids.push(input_id);
}
// A dynamic future is not a valid input.
ValueType::DynamicFuture => bail!("A dynamic future is not a valid input"),
}
}
// Compute `challenge` as `HashToScalar(r * G, pk_sig, pr_sig, signer, [tvk, tcm, function ID, is_root, program checksum?, 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,
is_dynamic,
})
}
}