Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

fix: Ensure that input doesn't exceed the modulus, this time for real #37

Merged
merged 1 commit into from
Oct 31, 2023
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension


Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions light-poseidon/Cargo.toml
Original file line number Diff line number Diff line change
@@ -12,6 +12,7 @@ edition = "2021"
[dependencies]
ark-bn254 = "0.4.0"
ark-ff = "0.4.0"
num-bigint = "0.4.4"
thiserror = "1.0"

[dev-dependencies]
103 changes: 55 additions & 48 deletions light-poseidon/src/lib.rs
Original file line number Diff line number Diff line change
@@ -156,12 +156,16 @@ pub enum PoseidonError {
len: usize,
modulus_bytes_len: usize,
},
#[error("Failed to convert bytes {bytes:?} into a prime field element")]
BytesToPrimeFieldElement { bytes: Vec<u8> },
#[error("Input is larger than the modulus of the prime field.")]
InputLargerThanModulus,
#[error("Failed to convert a vector of bytes into an array.")]
VecToArray,
#[error("Failed to convert the number of inputs from u64 to u8.")]
U64Tou8,
#[error("Failed to convert bytes to BigInt")]
BytesToBigInt,
#[error("Invalid width: {width}. Choose a width between 2 and 16 for 1 to 15 inputs.")]
InvalidWidthCircom { width: usize, max_limit: usize },
}
@@ -413,49 +417,32 @@ impl<F: PrimeField> PoseidonHasher<F> for Poseidon<F> {
}
}

impl<F: PrimeField> PoseidonBytesHasher for Poseidon<F> {
fn hash_bytes_le(&mut self, inputs: &[&[u8]]) -> Result<[u8; HASH_LEN], PoseidonError> {
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| validate_bytes_length::<F>(input))
.collect();
let inputs = inputs?;
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| bytes_to_prime_field_element(input))
.collect();
let inputs = inputs?;
let hash = self.hash(&inputs)?;

hash.into_bigint()
.to_bytes_le()
.try_into()
.map_err(|_| PoseidonError::VecToArray)
}
macro_rules! impl_hash_bytes {
($fn_name:ident, $bytes_to_prime_field_element_fn:ident, $to_bytes_fn:ident) => {
fn $fn_name(&mut self, inputs: &[&[u8]]) -> Result<[u8; HASH_LEN], PoseidonError> {
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| validate_bytes_length::<F>(input))
.collect();
let inputs = inputs?;
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| $bytes_to_prime_field_element_fn(input))
.collect();
let inputs = inputs?;
let hash = self.hash(&inputs)?;

fn hash_bytes_be(&mut self, inputs: &[&[u8]]) -> Result<[u8; HASH_LEN], PoseidonError> {
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| validate_bytes_length::<F>(input))
.collect();
let inputs = inputs?;
let inputs: Result<Vec<_>, _> = inputs
.iter()
.map(|input| {
let mut input = input.to_vec();
input.reverse();
input
})
.map(|input| bytes_to_prime_field_element(input.as_slice()))
.collect();
let inputs = inputs?;
let hash = self.hash(&inputs)?;
hash.into_bigint()
.$to_bytes_fn()
.try_into()
.map_err(|_| PoseidonError::VecToArray)
}
};
}

hash.into_bigint()
.to_bytes_be()
.try_into()
.map_err(|_| PoseidonError::VecToArray)
}
impl<F: PrimeField> PoseidonBytesHasher for Poseidon<F> {
impl_hash_bytes!(hash_bytes_le, bytes_to_prime_field_element_le, to_bytes_le);
impl_hash_bytes!(hash_bytes_be, bytes_to_prime_field_element_be, to_bytes_be);
}

/// Checks whether a slice of bytes is not empty or its length does not exceed
@@ -485,15 +472,35 @@ where
Ok(input)
}

/// Converts a slice of bytes into a prime field element, represented by the
/// [`ark_ff::PrimeField`](ark_ff::PrimeField)) trait.
fn bytes_to_prime_field_element<F>(input: &[u8]) -> Result<F, PoseidonError>
where
F: PrimeField,
{
F::from_random_bytes(input).ok_or(PoseidonError::InputLargerThanModulus)
macro_rules! impl_bytes_to_prime_field_element {
($name:ident, $from_bytes_method:ident, $endianess:expr) => {
#[doc = "Converts a slice of "]
#[doc = $endianess]
#[doc = "-endian bytes into a prime field element, \
represented by the [`ark_ff::PrimeField`](ark_ff::PrimeField) trait."]
fn $name<F>(input: &[u8]) -> Result<F, PoseidonError>
where
F: PrimeField,
{
let element = num_bigint::BigUint::$from_bytes_method(input);
let element = F::BigInt::try_from(element).map_err(|_| PoseidonError::BytesToBigInt)?;

// In theory, `F::from_bigint` should also perform a check whether input is
// larger than modulus (and return `None` if it is), but it's not reliable...
// To be sure, we check it ourselves.
if element >= F::MODULUS {
return Err(PoseidonError::InputLargerThanModulus);
}
let element = F::from_bigint(element).ok_or(PoseidonError::InputLargerThanModulus)?;

Ok(element)
}
};
}

impl_bytes_to_prime_field_element!(bytes_to_prime_field_element_le, from_bytes_le, "little");
impl_bytes_to_prime_field_element!(bytes_to_prime_field_element_be, from_bytes_be, "big");

impl<F: PrimeField> Poseidon<F> {
pub fn new_circom(nr_inputs: usize) -> Result<Poseidon<Fr>, PoseidonError> {
Self::with_domain_tag_circom(nr_inputs, Fr::zero())
48 changes: 41 additions & 7 deletions light-poseidon/tests/bn254_fq_x5.rs
Original file line number Diff line number Diff line change
@@ -224,13 +224,13 @@ test_invalid_input_length!(
hash_bytes_le
);

macro_rules! test_fuzz_input_gt_field_size {
macro_rules! test_fuzz_input_gte_field_size {
($name:ident, $method:ident, $to_bytes_method:ident) => {
#[test]
fn $name() {
let mut greater_than_field_size = Fr::MODULUS;
let mut rng = rand::thread_rng();
let random_number = rng.gen_range(1u64..1_000_000u64);
let random_number = rng.gen_range(0u64..1_000_000u64);
greater_than_field_size.add_with_carry(&BigInteger256::from(random_number));
let greater_than_field_size = greater_than_field_size.$to_bytes_method();

@@ -251,19 +251,19 @@ macro_rules! test_fuzz_input_gt_field_size {
};
}

test_fuzz_input_gt_field_size!(
test_fuzz_input_gte_field_size!(
test_fuzz_poseidon_bn254_fq_hash_bytes_be_input_gt_field_size,
hash_bytes_be,
to_bytes_be
);

test_fuzz_input_gt_field_size!(
test_fuzz_input_gte_field_size!(
test_fuzz_poseidon_bn254_fq_hash_bytes_le_input_gt_field_size,
hash_bytes_le,
to_bytes_le
);

macro_rules! test_input_gt_field_size {
macro_rules! test_input_gte_field_size {
($name:ident, $method:ident, $greater_than_field_size:expr) => {
#[test]
fn $name() {
@@ -282,7 +282,25 @@ macro_rules! test_input_gt_field_size {
};
}

test_input_gt_field_size!(
test_input_gte_field_size!(
test_poseidon_bn254_fq_hash_bytes_be_input_gt_field_size_our_check,
hash_bytes_be,
[
216, 137, 85, 159, 239, 194, 107, 138, 254, 68, 21, 16, 165, 41, 64, 148, 208, 198, 201,
59, 220, 102, 142, 81, 49, 251, 174, 183, 183, 182, 4, 32,
]
);

test_input_gte_field_size!(
test_poseidon_bn254_fq_hash_bytes_le_input_gt_field_size_our_check,
hash_bytes_le,
[
32, 4, 182, 183, 183, 174, 251, 49, 81, 142, 102, 220, 59, 201, 198, 208, 148, 64, 41, 165,
16, 21, 68, 254, 138, 107, 194, 239, 159, 85, 137, 216,
]
);

test_input_gte_field_size!(
test_poseidon_bn254_fq_hash_bytes_be_input_gt_field_size,
hash_bytes_be,
[
@@ -291,7 +309,7 @@ test_input_gt_field_size!(
]
);

test_input_gt_field_size!(
test_input_gte_field_size!(
test_poseidon_bn254_fq_hash_bytes_le_input_gt_field_size,
hash_bytes_le,
[
@@ -300,6 +318,22 @@ test_input_gt_field_size!(
]
);

#[test]
fn test_input_eq_field_size_be() {
let mut hasher = Poseidon::<Fr>::new_circom(1).unwrap();
let input = Fr::MODULUS.to_bytes_be();
let hash = hasher.hash_bytes_be(&[&input]);
assert_eq!(hash, Err(PoseidonError::InputLargerThanModulus));
}

#[test]
fn test_input_eq_field_size_le() {
let mut hasher = Poseidon::<Fr>::new_circom(1).unwrap();
let input = Fr::MODULUS.to_bytes_le();
let hash = hasher.hash_bytes_le(&[&input]);
assert_eq!(hash, Err(PoseidonError::InputLargerThanModulus));
}

#[test]
fn test_endianness() {
let mut hasher = Poseidon::<Fr>::new_circom(2).unwrap();