feat(hints): add NewHint#29 (#986)

* Add `COMPUTE_SLOPE_WHITELIST` hint

* Update changelog

* Fix: add missing return to cairo program

* Add `EC_DOUBLE_SCOPE_WHITELIST` hint

* Update changelog

* Add missing newline

CHANGELOG.md

@@ -218,6 +218,33 @@
 
     Used by the common library function `uint256_mul_div_mod`
 
+* Add missing hint on cairo_secp lib [#986]:
+
+    `BuiltinHintProcessor` now supports the following hint:
+    ```python
+        from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
+        from starkware.python.math_utils import div_mod
+
+        # Compute the slope.
+        x = pack(ids.pt.x, PRIME)
+        y = pack(ids.pt.y, PRIME)
+        value = slope = div_mod(3 * x ** 2, 2 * y, SECP_P)
+    ```
+
+* Add missing hint on cairo_secp lib [#984]:
+    `BuiltinHintProcessor` now supports the following hint:
+    ```python
+        from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
+        from starkware.python.math_utils import div_mod
+
+        # Compute the slope.
+        x0 = pack(ids.pt0.x, PRIME)
+        y0 = pack(ids.pt0.y, PRIME)
+        x1 = pack(ids.pt1.x, PRIME)
+        y1 = pack(ids.pt1.y, PRIME)
+        value = slope = div_mod(y0 - y1, x0 - x1, SECP_P)
+    ```
+
 * Move `Memory` into `MemorySegmentManager` [#830](/~https://github.com/lambdaclass/cairo-rs/pull/830)
     * Structural changes:
         * Remove `memory: Memory` field from `VirtualMachine`

cairo_programs/ed25519_ec.cairo

@@ -18,6 +18,37 @@ struct EcPoint {
     y: BigInt3,
 }
 
+// Returns the slope of the elliptic curve at the given point.
+// The slope is used to compute pt + pt.
+// Assumption: pt != 0.
+func compute_doubling_slope{range_check_ptr}(pt: EcPoint) -> (slope: BigInt3) {
+    // Note that y cannot be zero: assume that it is, then pt = -pt, so 2 * pt = 0, which
+    // contradicts the fact that the size of the curve is odd.
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
+        from starkware.python.math_utils import div_mod
+
+        # Compute the slope.
+        x = pack(ids.pt.x, PRIME)
+        y = pack(ids.pt.y, PRIME)
+        value = slope = div_mod(3 * x ** 2, 2 * y, SECP_P)
+    %}
+    let (slope: BigInt3) = nondet_bigint3();
+
+    let (x_sqr: UnreducedBigInt3) = unreduced_sqr(pt.x);
+    let (slope_y: UnreducedBigInt3) = unreduced_mul(slope, pt.y);
+
+    verify_zero(
+        UnreducedBigInt3(
+            d0=3 * x_sqr.d0 - 2 * slope_y.d0,
+            d1=3 * x_sqr.d1 - 2 * slope_y.d1,
+            d2=3 * x_sqr.d2 - 2 * slope_y.d2,
+        ),
+    );
+
+    return (slope=slope);
+}
+
 // Returns the slope of the line connecting the two given points.
 // The slope is used to compute pt0 + pt1.
 // Assumption: pt0.x != pt1.x (mod secp256k1_prime).
@@ -49,6 +80,22 @@ func compute_slope{range_check_ptr: felt}(pt0: EcPoint, pt1: EcPoint) -> (slope:
     return (slope=slope);
 }
 
+func test_compute_double_slope{range_check_ptr: felt}() {
+    let x = BigInt3(d0=33, d1=24, d2=12412);
+    let y = BigInt3(d0=3232, d1=122, d2=31415);
+
+    let pt = EcPoint(x=x, y=y);
+
+    // Compute slope
+    let (slope) = compute_doubling_slope(pt);
+
+    assert slope = BigInt3(
+        d0=56007611085086895200895667, d1=15076814030975805918069142, d2=6556143173243739984479201
+    );
+
+    return ();
+}
+
 func test_compute_slope{range_check_ptr: felt}() {
     let x0 = BigInt3(d0=1, d1=5, d2=10);
     let y0 = BigInt3(d0=2, d1=4, d2=20);
@@ -71,6 +118,7 @@ func test_compute_slope{range_check_ptr: felt}() {
 }
 
 func main{range_check_ptr: felt}() {
+    test_compute_double_slope();
     test_compute_slope();
 
     return ();

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -358,9 +358,20 @@ impl HintProcessor for BuiltinHintProcessor {
             hint_code::EC_NEGATE => {
                 ec_negate(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
             }
-            hint_code::EC_DOUBLE_SCOPE => {
-                compute_doubling_slope(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
-            }
+            hint_code::EC_DOUBLE_SCOPE => compute_doubling_slope(
+                vm,
+                exec_scopes,
+                &hint_data.ids_data,
+                &hint_data.ap_tracking,
+                "point",
+            ),
+            hint_code::EC_DOUBLE_SCOPE_WHITELIST => compute_doubling_slope(
+                vm,
+                exec_scopes,
+                &hint_data.ids_data,
+                &hint_data.ap_tracking,
+                "pt",
+            ),
             hint_code::COMPUTE_SLOPE => compute_slope(
                 vm,
                 exec_scopes,

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -467,6 +467,14 @@ x = pack(ids.point.x, PRIME)
 y = pack(ids.point.y, PRIME)
 value = slope = ec_double_slope(point=(x, y), alpha=0, p=SECP_P)"#;
 
+pub(crate) const EC_DOUBLE_SCOPE_WHITELIST: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
+from starkware.python.math_utils import div_mod
+
+# Compute the slope.
+x = pack(ids.pt.x, PRIME)
+y = pack(ids.pt.y, PRIME)
+value = slope = div_mod(3 * x ** 2, 2 * y, SECP_P)"#;
+
 pub(crate) const COMPUTE_SLOPE: &str = r#"from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack
 from starkware.python.math_utils import line_slope
 

src/hint_processor/builtin_hint_processor/secp/ec_utils.rs

@@ -84,9 +84,10 @@ pub fn compute_doubling_slope(
     exec_scopes: &mut ExecutionScopes,
     ids_data: &HashMap<String, HintReference>,
     ap_tracking: &ApTracking,
+    point_alias: &str,
 ) -> Result<(), HintError> {
     //ids.point
-    let point = EcPoint::from_var_name("point", vm, ids_data, ap_tracking)?;
+    let point = EcPoint::from_var_name(point_alias, vm, ids_data, ap_tracking)?;
 
     let value = ec_double_slope(&(pack(point.x), pack(point.y)), &BigInt::zero(), &SECP_P);
     exec_scopes.insert_value("value", value.clone());
@@ -357,6 +358,47 @@ mod tests {
         );
     }
 
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn run_compute_doubling_slope_wdivmod_ok() {
+        let hint_code = "from starkware.cairo.common.cairo_secp.secp_utils import SECP_P, pack\nfrom starkware.python.math_utils import div_mod\n\n# Compute the slope.\nx = pack(ids.pt.x, PRIME)\ny = pack(ids.pt.y, PRIME)\nvalue = slope = div_mod(3 * x ** 2, 2 * y, SECP_P)";
+        let mut vm = vm_with_range_check!();
+        vm.segments = segments![
+            ((1, 0), 614323u64),
+            ((1, 1), 5456867u64),
+            ((1, 2), 101208u64),
+            ((1, 3), 773712524u64),
+            ((1, 4), 77371252u64),
+            ((1, 5), 5298795u64)
+        ];
+
+        //Initialize fp
+        vm.run_context.fp = 1;
+
+        let ids_data = ids_data!["pt"];
+        let mut exec_scopes = ExecutionScopes::new();
+
+        //Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Ok(()));
+        check_scope!(
+            &exec_scopes,
+            [
+                (
+                    "value",
+                    bigint_str!(
+            "40442433062102151071094722250325492738932110061897694430475034100717288403728"
+        )
+                ),
+                (
+                    "slope",
+                    bigint_str!(
+            "40442433062102151071094722250325492738932110061897694430475034100717288403728"
+        )
+                )
+            ]
+        );
+    }
+
     #[test]
     #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
     fn run_compute_slope_ok() {