feat(blockifier): add secp-related logic

crates/blockifier/src/execution.rs

@@ -9,6 +9,8 @@ pub mod entry_point_execution;
 pub mod errors;
 pub mod execution_utils;
 pub mod hint_code;
+pub mod secp;
+
 #[cfg(feature = "cairo_native")]
 pub mod native;
 pub mod stack_trace;

crates/blockifier/src/execution/native/syscall_handler.rs

@@ -1,6 +1,10 @@
 use std::collections::HashSet;
+use std::convert::From;
+use std::fmt;
 use std::hash::RandomState;
 
+use ark_ec::short_weierstrass::{Affine, Projective, SWCurveConfig};
+use ark_ff::PrimeField;
 use cairo_native::starknet::{
     ExecutionInfo,
     ExecutionInfoV2,
@@ -10,13 +14,15 @@ use cairo_native::starknet::{
     SyscallResult,
     U256,
 };
+use cairo_native::starknet_stub::u256_to_biguint;
 use cairo_vm::vm::runners::cairo_runner::ExecutionResources;
 use starknet_api::state::StorageKey;
 use starknet_types_core::felt::Felt;
 
 use crate::execution::call_info::{CallInfo, OrderedEvent, OrderedL2ToL1Message, Retdata};
 use crate::execution::entry_point::{CallEntryPoint, EntryPointExecutionContext};
 use crate::execution::native::utils::encode_str_as_felts;
+use crate::execution::secp;
 use crate::execution::syscalls::hint_processor::{SyscallCounter, OUT_OF_GAS_ERROR};
 use crate::execution::syscalls::SyscallSelector;
 use crate::state::state_api::State;
@@ -320,3 +326,77 @@ impl<'state> StarknetSyscallHandler for &mut NativeSyscallHandler<'state> {
         todo!("Implement sha256_process_block syscall.");
     }
 }
+
+// todo(xrvdg) remove dead_code annotation after adding syscalls
+#[allow(dead_code)]
+impl<Curve: SWCurveConfig> Secp256Point<Curve>
+where
+    Curve::BaseField: PrimeField, // constraint for get_point_by_id
+{
+    /// Given a (x,y) pair it will
+    /// - return the point at infinity for (0,0)
+    /// - Err if either x or y is outside of the modulus
+    /// - Ok(None) if (x,y) are within the modules but not on the curve
+    /// - Ok(Some(Point)) if (x,y) are on the curve
+    fn new(x: U256, y: U256) -> Result<Option<Self>, Vec<Felt>> {
+        let x = u256_to_biguint(x);
+        let y = u256_to_biguint(y);
+
+        match secp::new_affine(x, y) {
+            Ok(None) => Ok(None),
+            Ok(Some(affine)) => Ok(Some(Secp256Point(affine))),
+            Err(error) => Err(encode_str_as_felts(&error.to_string())),
+        }
+    }
+
+    fn add(p0: Self, p1: Self) -> Self {
+        let result: Projective<Curve> = p0.0 + p1.0;
+        Secp256Point(result.into())
+    }
+
+    fn mul(p: Self, m: U256) -> Self {
+        let result = p.0 * Curve::ScalarField::from(u256_to_biguint(m));
+        Secp256Point(result.into())
+    }
+
+    fn get_point_from_x(x: U256, y_parity: bool) -> Result<Option<Self>, Vec<Felt>> {
+        let x = u256_to_biguint(x);
+
+        match secp::get_point_from_x(x, y_parity) {
+            Ok(None) => Ok(None),
+            Ok(Some(point)) => Ok(Some(Secp256Point(point))),
+            Err(error) => Err(encode_str_as_felts(&error.to_string())),
+        }
+    }
+}
+
+/// Data structure to tie together k1 and r1 points to it's corresponding
+/// `Affine<Curve>`
+#[derive(PartialEq, Clone, Copy)]
+struct Secp256Point<Curve: SWCurveConfig>(Affine<Curve>);
+
+impl<Curve: SWCurveConfig> fmt::Debug for Secp256Point<Curve> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("Secp256Point").field(&self.0).finish()
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use cairo_native::starknet::U256;
+
+    use super::Secp256Point;
+
+    #[test]
+    fn infinity_test() {
+        let p1 =
+            Secp256Point::<ark_secp256k1::Config>::get_point_from_x(U256 { lo: 1, hi: 0 }, false)
+                .unwrap()
+                .unwrap();
+
+        let p2 = Secp256Point::mul(p1, U256 { lo: 0, hi: 0 });
+        assert!(p2.0.infinity);
+
+        assert_eq!(p1, Secp256Point::add(p1, p2));
+    }
+}

crates/blockifier/src/execution/secp.rs

@@ -0,0 +1,80 @@
+use ark_ec::short_weierstrass::{Affine, SWCurveConfig};
+use ark_ff::{PrimeField, Zero};
+use starknet_types_core::felt::Felt;
+
+use super::syscalls::hint_processor::{SyscallExecutionError, INVALID_ARGUMENT};
+
+pub fn get_point_from_x<Curve: SWCurveConfig>(
+    x: num_bigint::BigUint,
+    y_parity: bool,
+) -> Result<Option<Affine<Curve>>, SyscallExecutionError>
+where
+    Curve::BaseField: PrimeField, // constraint for get_point_by_id
+{
+    modulus_bound_check::<Curve>(&[&x])?;
+
+    let x = x.into();
+    let maybe_ec_point = Affine::<Curve>::get_ys_from_x_unchecked(x)
+        .map(|(smaller, greater)| {
+            // Return the correct y coordinate based on the parity.
+            if ark_ff::BigInteger::is_odd(&smaller.into_bigint()) == y_parity {
+                smaller
+            } else {
+                greater
+            }
+        })
+        .map(|y| Affine::<Curve>::new_unchecked(x, y))
+        .filter(|p| p.is_in_correct_subgroup_assuming_on_curve());
+
+    Ok(maybe_ec_point)
+}
+
+pub fn new_affine<Curve: SWCurveConfig>(
+    x: num_bigint::BigUint,
+    y: num_bigint::BigUint,
+) -> Result<Option<Affine<Curve>>, SyscallExecutionError>
+where
+    Curve::BaseField: PrimeField, // constraint for get_point_by_id
+{
+    modulus_bound_check::<Curve>(&[&x, &y])?;
+
+    Ok(maybe_affine(x.into(), y.into()))
+}
+
+fn modulus_bound_check<Curve: SWCurveConfig>(
+    bounds: &[&num_bigint::BigUint],
+) -> Result<(), SyscallExecutionError>
+where
+    Curve::BaseField: PrimeField, // constraint for get_point_by_id
+{
+    let modulos = Curve::BaseField::MODULUS.into();
+
+    if bounds.iter().any(|p| **p >= modulos) {
+        let error = match Felt::from_hex(INVALID_ARGUMENT) {
+            Ok(err) => SyscallExecutionError::SyscallError { error_data: vec![err] },
+            Err(err) => SyscallExecutionError::from(err),
+        };
+
+        return Err(error);
+    }
+
+    Ok(())
+}
+
+/// Variation on [`Affine<Curve>::new`] that doesn't panic and maps (x,y) = (0,0) -> infinity
+fn maybe_affine<Curve: SWCurveConfig>(
+    x: Curve::BaseField,
+    y: Curve::BaseField,
+) -> Option<Affine<Curve>> {
+    let ec_point = if x.is_zero() && y.is_zero() {
+        Affine::<Curve>::identity()
+    } else {
+        Affine::<Curve>::new_unchecked(x, y)
+    };
+
+    if ec_point.is_on_curve() && ec_point.is_in_correct_subgroup_assuming_on_curve() {
+        Some(ec_point)
+    } else {
+        None
+    }
+}

crates/blockifier/src/execution/syscalls/secp.rs

@@ -1,19 +1,15 @@
-use ark_ec::short_weierstrass;
-use ark_ec::short_weierstrass::SWCurveConfig;
-use ark_ff::{BigInteger, PrimeField};
+use ark_ec::short_weierstrass::{self, SWCurveConfig};
+use ark_ff::PrimeField;
 use cairo_vm::types::relocatable::Relocatable;
 use cairo_vm::vm::vm_core::VirtualMachine;
 use num_bigint::BigUint;
-use num_traits::{ToPrimitive, Zero};
+use num_traits::ToPrimitive;
 use starknet_types_core::felt::Felt;
 
 use crate::abi::sierra_types::{SierraType, SierraU256};
 use crate::execution::execution_utils::{felt_from_ptr, write_maybe_relocatable, write_u256};
-use crate::execution::syscalls::hint_processor::{
-    felt_to_bool,
-    SyscallHintProcessor,
-    INVALID_ARGUMENT,
-};
+use crate::execution::secp::new_affine;
+use crate::execution::syscalls::hint_processor::{felt_to_bool, SyscallHintProcessor};
 use crate::execution::syscalls::{
     SyscallExecutionError,
     SyscallRequest,
@@ -50,26 +46,9 @@ where
         &mut self,
         request: SecpGetPointFromXRequest,
     ) -> SyscallResult<SecpGetPointFromXResponse> {
-        let modulos = Curve::BaseField::MODULUS.into();
-
-        if request.x >= modulos {
-            return Err(SyscallExecutionError::SyscallError {
-                error_data: vec![
-                    Felt::from_hex(INVALID_ARGUMENT).map_err(SyscallExecutionError::from)?,
-                ],
-            });
-        }
-
-        let x = request.x.into();
-        let maybe_ec_point = short_weierstrass::Affine::<Curve>::get_ys_from_x_unchecked(x)
-            .map(|(smaller, greater)| {
-                // Return the correct y coordinate based on the parity.
-                if smaller.into_bigint().is_odd() == request.y_parity { smaller } else { greater }
-            })
-            .map(|y| short_weierstrass::Affine::<Curve>::new_unchecked(x, y))
-            .filter(|p| p.is_in_correct_subgroup_assuming_on_curve());
-
-        Ok(SecpGetPointFromXResponse {
+        let affine = crate::execution::secp::get_point_from_x(request.x, request.y_parity);
+
+        affine.map(|maybe_ec_point| SecpGetPointFromXResponse {
             optional_ec_point_id: maybe_ec_point.map(|ec_point| self.allocate_point(ec_point)),
         })
     }
@@ -81,27 +60,10 @@ where
     }
 
     pub fn secp_new(&mut self, request: SecpNewRequest) -> SyscallResult<SecpNewResponse> {
-        let modulos = Curve::BaseField::MODULUS.into();
-        let (x, y) = (request.x, request.y);
-        if x >= modulos || y >= modulos {
-            return Err(SyscallExecutionError::SyscallError {
-                error_data: vec![
-                    Felt::from_hex(INVALID_ARGUMENT).map_err(SyscallExecutionError::from)?,
-                ],
-            });
-        }
-        let ec_point = if x.is_zero() && y.is_zero() {
-            short_weierstrass::Affine::<Curve>::identity()
-        } else {
-            short_weierstrass::Affine::<Curve>::new_unchecked(x.into(), y.into())
-        };
-        let optional_ec_point_id =
-            if ec_point.is_on_curve() && ec_point.is_in_correct_subgroup_assuming_on_curve() {
-                Some(self.allocate_point(ec_point))
-            } else {
-                None
-            };
-        Ok(SecpNewResponse { optional_ec_point_id })
+        let affine = new_affine::<Curve>(request.x, request.y);
+        affine.map(|maybe_ec_point| SecpNewResponse {
+            optional_ec_point_id: maybe_ec_point.map(|point| self.allocate_point(point)),
+        })
     }
 
     fn allocate_point(&mut self, ec_point: short_weierstrass::Affine<Curve>) -> usize {