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masp: check size and hash of params in node
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@juped
juped committed Jun 26, 2023
1 parent 3b38092 commit 26ad3d3
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Showing 2 changed files with 134 additions and 62 deletions.
2 changes: 1 addition & 1 deletion shared/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,7 @@ wasmer-engine-universal = {version = "=2.2.0", optional = true}
wasmer-vm = {version = "2.2.0", optional = true}
wasmparser.workspace = true
masp_primitives.workspace = true
masp_proofs.workspace = true
masp_proofs = { git = "https://github.com/anoma/masp", rev = "cfea8c95d3f73077ca3e25380fd27e5b46e828fd", default-features = false, features = ["local-prover", "download-params"] }
rand = {version = "0.8", default-features = false, optional = true}
rand_core = {version = "0.6", default-features = false, optional = true}
zeroize.workspace = true
Expand Down
194 changes: 133 additions & 61 deletions shared/src/ledger/masp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@ use std::collections::hash_map::Entry;
use std::collections::{BTreeMap, HashMap, HashSet};
use std::env;
use std::fmt::Debug;
use std::fs::File;
#[cfg(feature = "masp-tx-gen")]
use std::ops::Deref;
use std::path::PathBuf;
Expand Down Expand Up @@ -44,9 +43,7 @@ use masp_primitives::transaction::{
TransparentAddress, Unauthorized,
};
use masp_primitives::zip32::{ExtendedFullViewingKey, ExtendedSpendingKey};
use masp_proofs::bellman::groth16::{
prepare_verifying_key, PreparedVerifyingKey,
};
use masp_proofs::bellman::groth16::PreparedVerifyingKey;
use masp_proofs::bls12_381::Bls12;
use masp_proofs::prover::LocalTxProver;
use masp_proofs::sapling::SaplingVerificationContext;
Expand Down Expand Up @@ -90,62 +87,37 @@ pub const OUTPUT_NAME: &str = "masp-output.params";
/// Convert circuit name
pub const CONVERT_NAME: &str = "masp-convert.params";

enum MaspParams {
Spend,
Convert,
Output,
}

/// Generic helper to load Sapling params.
fn load_params(name: MaspParams) -> (
masp_proofs::bellman::groth16::Parameters<Bls12>,
masp_proofs::bellman::groth16::PreparedVerifyingKey<Bls12>,
fn load_pvks() -> (
PreparedVerifyingKey<Bls12>,
PreparedVerifyingKey<Bls12>,
PreparedVerifyingKey<Bls12>,
) {
let params_name = match name {
MaspParams::Spend => SPEND_NAME,
MaspParams::Convert => CONVERT_NAME,
MaspParams::Output => OUTPUT_NAME,
};

let params_dir = get_params_dir();
let params_path = params_dir.join(params_name);
if !params_path.exists() {
#[cfg(feature = "masp_proofs/download-params")]
masp_proofs::download_parameters()
.expect("MASP parameters not present or downloadable");
#[cfg(not(feature = "masp_proofs/download-params"))]
panic!("MASP parameters not present or downloadable");
}
let param_f = File::open(params_path).unwrap();
let params =
masp_proofs::bellman::groth16::Parameters::read(&param_f, false)
.unwrap();
let vk = prepare_verifying_key(&params.vk);
(params, vk)
}

/// Load Sapling spend params.
pub fn load_spend_params() -> (
masp_proofs::bellman::groth16::Parameters<Bls12>,
masp_proofs::bellman::groth16::PreparedVerifyingKey<Bls12>,
) {
load_params(MaspParams::Spend)
}
let [spend_path, convert_path, output_path] =
[SPEND_NAME, CONVERT_NAME, OUTPUT_NAME].map(|p| params_dir.join(p));

/// Load Sapling convert params.
pub fn load_convert_params() -> (
masp_proofs::bellman::groth16::Parameters<Bls12>,
masp_proofs::bellman::groth16::PreparedVerifyingKey<Bls12>,
) {
load_params(MaspParams::Convert)
}

/// Load Sapling output params.
pub fn load_output_params() -> (
masp_proofs::bellman::groth16::Parameters<Bls12>,
masp_proofs::bellman::groth16::PreparedVerifyingKey<Bls12>,
) {
load_params(MaspParams::Output)
if !spend_path.exists() || !convert_path.exists() || !output_path.exists() {
let paths = masp_proofs::download_masp_parameters(None).expect(
"MASP parameters were not present, expected the download to \
succeed",
);
if paths.spend != spend_path
|| paths.convert != convert_path
|| paths.output != output_path
{
panic!(
"unrecoverable: downloaded missing masp params, but to an \
unfamiliar path"
)
}
}
// size and blake2b checked here
let params = masp_proofs::load_parameters(
spend_path.as_path(),
output_path.as_path(),
convert_path.as_path(),
);
(params.spend_vk, params.convert_vk, params.output_vk)
}

/// check_spend wrapper
Expand Down Expand Up @@ -277,9 +249,7 @@ pub fn verify_shielded_tx(transaction: &Transaction) -> bool {

tracing::info!("sighash computed");

let (_, spend_pvk) = load_spend_params();
let (_, convert_pvk) = load_convert_params();
let (_, output_pvk) = load_output_params();
let (spend_pvk, convert_pvk, output_pvk) = load_pvks();

let mut ctx = SaplingVerificationContext::new(true);
let spends_valid = sapling_bundle.shielded_spends.iter().all(|spend| {
Expand Down Expand Up @@ -365,7 +335,7 @@ impl<P1, R1, N1>

/// Abstracts platform specific details away from the logic of shielded pool
/// operations.
#[async_trait(?Send)]
#[async_trait(? Send)]
pub trait ShieldedUtils:
Sized + BorshDeserialize + BorshSerialize + Default + Clone
{
Expand Down Expand Up @@ -1546,3 +1516,105 @@ fn convert_amount(
.expect("invalid value for amount");
(asset_type, amount)
}

mod tests {
/// quick and dirty test. will fail on size check
#[test]
#[should_panic(expected = "parameter file size is not correct")]
fn test_wrong_masp_params() {
use std::io::Write;

use super::{CONVERT_NAME, OUTPUT_NAME, SPEND_NAME};

let tempdir = tempfile::tempdir()
.expect("expected a temp dir")
.into_path();
let fake_params_paths =
[SPEND_NAME, CONVERT_NAME, OUTPUT_NAME].map(|p| tempdir.join(p));
for path in fake_params_paths {
let mut f =
std::fs::File::create(path).expect("expected a temp file");
f.write_all(b"fake params")
.expect("expected a writable temp file");
f.sync_all()
.expect("expected a writable temp file (on sync)");
}

std::env::set_var(super::ENV_VAR_MASP_PARAMS_DIR, tempdir.as_os_str());
// should panic here
super::load_pvks();
}

/// a more involved test, using dummy parameters with the right
/// size but the wrong hash.
#[test]
#[should_panic(expected = "parameter file is not correct")]
fn test_wrong_masp_params_hash() {
use masp_primitives::ff::PrimeField;
use masp_proofs::bellman::groth16::{
generate_random_parameters, Parameters,
};
use masp_proofs::bellman::{Circuit, ConstraintSystem, SynthesisError};
use masp_proofs::bls12_381::{Bls12, Scalar};

use super::{CONVERT_NAME, OUTPUT_NAME, SPEND_NAME};

struct FakeCircuit<E: PrimeField> {
x: E,
}

impl<E: PrimeField> Circuit<E> for FakeCircuit<E> {
fn synthesize<CS: ConstraintSystem<E>>(
self,
cs: &mut CS,
) -> Result<(), SynthesisError> {
let x = cs.alloc(|| "x", || Ok(self.x)).unwrap();
cs.enforce(
|| {
"this is an extra long constraint name so that rustfmt \
is ok with wrapping the params of enforce()"
},
|lc| lc + x,
|lc| lc + x,
|lc| lc + x,
);
Ok(())
}
}

let dummy_circuit = FakeCircuit { x: Scalar::zero() };
let mut rng = rand::thread_rng();
let fake_params: Parameters<Bls12> =
generate_random_parameters(dummy_circuit, &mut rng)
.expect("expected to generate fake params");

let tempdir = tempfile::tempdir()
.expect("expected a temp dir")
.into_path();
// TODO: get masp to export these consts
let fake_params_paths = [
(SPEND_NAME, 49848572u64),
(CONVERT_NAME, 22570940u64),
(OUTPUT_NAME, 16398620u64),
]
.map(|(p, s)| (tempdir.join(p), s));
for (path, size) in fake_params_paths {
let mut f =
std::fs::File::create(path).expect("expected a temp file");
fake_params
.write(&mut f)
.expect("expected a writable temp file");
// the dummy circuit has one constraint, and therefore its
// params should always be smaller than the large masp
// circuit params. so this truncate extends the file, and
// extra bytes at the end do not make it invalid.
f.set_len(size).expect("expected to truncate the temp file");
f.sync_all()
.expect("expected a writable temp file (on sync)");
}

std::env::set_var(super::ENV_VAR_MASP_PARAMS_DIR, tempdir.as_os_str());
// should panic here
super::load_pvks();
}
}

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