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.

Sign up for GitHub

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

Helpers for ECDSA in A3 #364

Merged
merged 3 commits into from
Apr 20, 2023
Merged

Helpers for ECDSA in A3 #364

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
2e43a5f
Add `stdlib_keccak` in cmake.
suyash67 Apr 11, 2023
fb32125
Add `random_element` to affine element.
suyash67 Apr 16, 2023
875117a
negate y conditionally.
suyash67 Apr 19, 2023
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
3 changes: 3 additions & 0 deletions cpp/src/CMakeLists.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -90,6 +90,7 @@ if(WASM)
$<TARGET_OBJECTS:stdlib_pedersen_commitment_objects>
$<TARGET_OBJECTS:stdlib_blake2s_objects>
$<TARGET_OBJECTS:stdlib_blake3s_objects>
$<TARGET_OBJECTS:stdlib_keccak_objects>
$<TARGET_OBJECTS:stdlib_sha256_objects>
$<TARGET_OBJECTS:stdlib_aes128_objects>
$<TARGET_OBJECTS:stdlib_merkle_tree_objects>
Expand Down Expand Up @@ -192,6 +193,7 @@ if(WASM)
$<TARGET_OBJECTS:stdlib_pedersen_commitment_objects>
$<TARGET_OBJECTS:stdlib_blake2s_objects>
$<TARGET_OBJECTS:stdlib_blake3s_objects>
$<TARGET_OBJECTS:stdlib_keccak_objects>
$<TARGET_OBJECTS:stdlib_sha256_objects>
$<TARGET_OBJECTS:stdlib_aes128_objects>
$<TARGET_OBJECTS:stdlib_merkle_tree_objects>
Expand Down Expand Up @@ -227,6 +229,7 @@ else()
$<TARGET_OBJECTS:stdlib_pedersen_commitment_objects>
$<TARGET_OBJECTS:stdlib_blake2s_objects>
$<TARGET_OBJECTS:stdlib_blake3s_objects>
$<TARGET_OBJECTS:stdlib_keccak_objects>
$<TARGET_OBJECTS:stdlib_sha256_objects>
$<TARGET_OBJECTS:stdlib_aes128_objects>
$<TARGET_OBJECTS:stdlib_merkle_tree_objects>
Expand Down
7 changes: 7 additions & 0 deletions cpp/src/barretenberg/ecc/groups/affine_element.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,13 @@ template <typename Fq, typename Fr, typename Params> class alignas(64) affine_el

constexpr bool on_curve() const noexcept;

/**
* @brief Samples a random point on the curve.
*
* @return A randomly chosen point on the curve
*/
static affine_element random_element(numeric::random::Engine* engine = nullptr) noexcept;

/**
* @brief Hash a seed value to curve.
*
Expand Down
29 changes: 29 additions & 0 deletions cpp/src/barretenberg/ecc/groups/affine_element_impl.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -202,5 +202,34 @@ affine_element<Fq, Fr, T> affine_element<Fq, Fr, T>::hash_to_curve(const uint64_

return affine_element<Fq, Fr, T>(x_out, y_out_);
}

template <typename Fq, typename Fr, typename T>
affine_element<Fq, Fr, T> affine_element<Fq, Fr, T>::random_element(numeric::random::Engine* engine) noexcept
{
bool found_one = false;
Fq yy;
Fq x;
Fq y;
while (!found_one) {
// Sample a random x-coordinate and check if it satisfies curve equation.
x = Fq::random_element(engine);
yy = x.sqr() * x + T::b;
if constexpr (T::has_a) {
yy += (x * T::a);
}
auto [found_root, y1] = yy.sqrt();
y = y1;

// Negate the y-coordinate based on a randomly sampled bit.
bool random_bit = (engine->get_random_uint8() & 1);
if (random_bit) {
y = -y;
}

found_one = found_root;
}
return affine_element<Fq, Fr, T>(x, y);
}

} // namespace group_elements
} // namespace barretenberg
2 changes: 1 addition & 1 deletion cpp/src/barretenberg/stdlib/primitives/bigfield/bigfield.hpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,7 +160,7 @@ template <typename Composer, typename T> class bigfield {
field_t<Composer> lo = binary_basis_limbs[0].element + (binary_basis_limbs[1].element * shift_1);
field_t<Composer> hi = binary_basis_limbs[2].element + (binary_basis_limbs[3].element * shift_1);
// n.b. this only works if NUM_LIMB_BITS * 2 is divisible by 8
ASSERT((NUM_LIMB_BITS / 8) * 8 == NUM_LIMB_BITS);
ASSERT((NUM_LIMB_BITS * 2 / 8) * 8 == NUM_LIMB_BITS * 2);
result.write(byte_array<Composer>(hi, 32 - (NUM_LIMB_BITS / 4)));
result.write(byte_array<Composer>(lo, (NUM_LIMB_BITS / 4)));
return result;
Expand Down