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//! Abstractions over the proving system and parameters for ease of use.
use ironfish_bellperson::groth16::{Parameters, PreparedVerifyingKey};
use blstrs::Bls12;
use std::path::Path;
use ironfish_primitives::{
merkle_tree::MerklePath,
sapling::{
prover::TxProver,
redjubjub::{PublicKey, Signature},
Diversifier, Node, PaymentAddress, ProofGenerationKey, Rseed,
},
transaction::components::{Amount, GROTH_PROOF_SIZE},
};
use crate::{load_parameters, parse_parameters, sapling::SaplingProvingContext};
#[cfg(feature = "local-prover")]
use crate::{default_params_folder, SAPLING_OUTPUT_NAME, SAPLING_SPEND_NAME};
/// An implementation of [`TxProver`] using Sapling Spend and Output parameters from
/// locally-accessible paths.
pub struct LocalTxProver {
spend_params: Parameters<Bls12>,
spend_vk: PreparedVerifyingKey<Bls12>,
output_params: Parameters<Bls12>,
}
impl LocalTxProver {
/// Creates a `LocalTxProver` using parameters from the given local paths.
///
/// # Examples
///
/// ```should_panic
/// use std::path::Path;
/// use ironfish_proofs::prover::LocalTxProver;
///
/// let tx_prover = LocalTxProver::new(
/// Path::new("/path/to/sapling-spend.params"),
/// Path::new("/path/to/sapling-output.params"),
/// );
/// ```
///
/// # Panics
///
/// This function will panic if the paths do not point to valid parameter files with
/// the expected hashes.
pub fn new(spend_path: &Path, output_path: &Path) -> Self {
let p = load_parameters(spend_path, output_path, None);
LocalTxProver {
spend_params: p.spend_params,
spend_vk: p.spend_vk,
output_params: p.output_params,
}
}
/// Creates a `LocalTxProver` using parameters specified as byte arrays.
///
/// # Examples
///
/// ```should_panic
/// use std::path::Path;
/// use ironfish_proofs::prover::LocalTxProver;
///
/// let tx_prover = LocalTxProver::from_bytes(&[0u8], &[0u8]);
/// ```
///
/// # Panics
///
/// This function will panic if the byte arrays do not contain valid parameters with
/// the expected hashes.
pub fn from_bytes(spend_param_bytes: &[u8], output_param_bytes: &[u8]) -> Self {
let p = parse_parameters(spend_param_bytes, output_param_bytes, None);
LocalTxProver {
spend_params: p.spend_params,
spend_vk: p.spend_vk,
output_params: p.output_params,
}
}
/// Attempts to create a `LocalTxProver` using parameters from the default local
/// location.
///
/// Returns `None` if any of the parameters cannot be found in the default local
/// location.
///
/// # Examples
///
/// ```
/// use ironfish_proofs::prover::LocalTxProver;
///
/// match LocalTxProver::with_default_location() {
/// Some(tx_prover) => (),
/// None => println!("Please run zcash-fetch-params or fetch-params.sh to download the parameters."),
/// }
/// ```
///
/// # Panics
///
/// This function will panic if the parameters in the default local location do not
/// have the expected hashes.
#[cfg(feature = "local-prover")]
#[cfg_attr(docsrs, doc(cfg(feature = "local-prover")))]
pub fn with_default_location() -> Option<Self> {
let params_dir = default_params_folder()?;
let (spend_path, output_path) = if params_dir.exists() {
(
params_dir.join(SAPLING_SPEND_NAME),
params_dir.join(SAPLING_OUTPUT_NAME),
)
} else {
return None;
};
if !(spend_path.exists() && output_path.exists()) {
return None;
}
Some(LocalTxProver::new(&spend_path, &output_path))
}
/// Creates a `LocalTxProver` using Sapling parameters bundled inside the binary.
///
/// This requires the `bundled-prover` feature, which will increase the binary size by
/// around 50 MiB.
#[cfg(feature = "bundled-prover")]
#[cfg_attr(docsrs, doc(cfg(feature = "bundled-prover")))]
pub fn bundled() -> Self {
let (spend_buf, output_buf) = wagyu_zcash_parameters::load_sapling_parameters();
let p = parse_parameters(&spend_buf[..], &output_buf[..], None);
LocalTxProver {
spend_params: p.spend_params,
spend_vk: p.spend_vk,
output_params: p.output_params,
}
}
}
impl TxProver for LocalTxProver {
type SaplingProvingContext = SaplingProvingContext;
fn new_sapling_proving_context(&self) -> Self::SaplingProvingContext {
SaplingProvingContext::new()
}
fn spend_proof(
&self,
ctx: &mut Self::SaplingProvingContext,
proof_generation_key: ProofGenerationKey,
diversifier: Diversifier,
rseed: Rseed,
ar: ironfish_jubjub::Fr,
value: u64,
anchor: blstrs::Scalar,
merkle_path: MerklePath<Node>,
) -> Result<([u8; GROTH_PROOF_SIZE], ironfish_jubjub::ExtendedPoint, PublicKey), ()> {
let (proof, cv, rk) = ctx.spend_proof(
proof_generation_key,
diversifier,
rseed,
ar,
value,
anchor,
merkle_path,
&self.spend_params,
&self.spend_vk,
)?;
let mut zkproof = [0u8; GROTH_PROOF_SIZE];
proof
.write(&mut zkproof[..])
.expect("should be able to serialize a proof");
Ok((zkproof, cv, rk))
}
fn output_proof(
&self,
ctx: &mut Self::SaplingProvingContext,
esk: ironfish_jubjub::Fr,
payment_address: PaymentAddress,
rcm: ironfish_jubjub::Fr,
value: u64,
) -> ([u8; GROTH_PROOF_SIZE], ironfish_jubjub::ExtendedPoint) {
let (proof, cv) = ctx.output_proof(esk, payment_address, rcm, value, &self.output_params);
let mut zkproof = [0u8; GROTH_PROOF_SIZE];
proof
.write(&mut zkproof[..])
.expect("should be able to serialize a proof");
(zkproof, cv)
}
fn binding_sig(
&self,
ctx: &mut Self::SaplingProvingContext,
value_balance: Amount,
sighash: &[u8; 32],
) -> Result<Signature, ()> {
ctx.binding_sig(value_balance, sighash)
}
}