Add NewHint#31 (#991)

* add program with div_mod_n

* make mul_s_inv program execute

* make mul_s_inv program execute

* add pack_modn_div_modn and mul_s_inv test

* add changes to changelog

* fix changelog merge

* fix changelog

* fix changelog style

---------

Co-authored-by: Mario Rugiero <[email protected]>

Author: mfachal

CHANGELOG.md

@@ -6,6 +6,21 @@
     * BugFix: Add missing `\n` character after traceback lines when the filename is missing ("Unknown Location")
 
 * 0.11 Support
+    * Add missing hints on cairo_secp lib [#991](https://github.com/lambdaclass/cairo-rs/pull/991):
+        `BuiltinHintProcessor` now supports the following hints:
+        ```python
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+        from starkware.python.math_utils import div_mod, safe_div
+
+        N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
+        x = pack(ids.x, PRIME) % N
+        s = pack(ids.s, PRIME) % N
+        value = res = div_mod(x, s, N)
+        ```
+        and: 
+        ```python
+        value = k = safe_div(res * s - x, N)
+        ```
     * Layouts update [#874](https://github.com/lambdaclass/cairo-rs/pull/874)
     * Keccak builtin updated [#873](https://github.com/lambdaclass/cairo-rs/pull/873), [#883](https://github.com/lambdaclass/cairo-rs/pull/883)
     * Changes to `ec_op` [#876](https://github.com/lambdaclass/cairo-rs/pull/876)
@@ -16,7 +31,6 @@
     * Added dynamic layout [#879](https://github.com/lambdaclass/cairo-rs/pull/879)
     * `get_segment_size` was exposed [#934](https://github.com/lambdaclass/cairo-rs/pull/934)
 
-
 * Add missing hint on cairo_secp lib [#990](https://github.com/lambdaclass/cairo-rs/pull/990):
 
     `BuiltinHintProcessor` now supports the following hint:

cairo_programs/mul_s_inv.cairo

@@ -0,0 +1,60 @@
+%builtins range_check
+
+// Source: https://github.com/NilFoundation/cairo-placeholder-verification/blob/382924c6f1c4f9673a12a31d19835e00978ab241/src/signatures/ed25519.cairo
+
+from starkware.cairo.common.cairo_secp.bigint import BASE, BigInt3, bigint_mul, nondet_bigint3
+from starkware.cairo.common.cairo_secp.constants import N0, N1, N2
+from starkware.cairo.common.cairo_secp.ec import EcPoint, ec_add, ec_mul
+
+from starkware.cairo.common.math import assert_nn_le, assert_not_zero
+
+// Computes x * s^(-1) modulo the size of the elliptic curve (N).
+func mul_s_inv{range_check_ptr}(x : BigInt3, s : BigInt3) -> (res : BigInt3){
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+        from starkware.python.math_utils import div_mod, safe_div
+
+        N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
+        x = pack(ids.x, PRIME) % N
+        s = pack(ids.s, PRIME) % N
+        value = res = div_mod(x, s, N)
+    %}
+    let (res) = nondet_bigint3();
+
+    %{ value = k = safe_div(res * s - x, N) %}
+    let (k) = nondet_bigint3();
+
+    let (res_s) = bigint_mul(res, s);
+    let n = BigInt3(N0, N1, N2);
+    let (k_n) = bigint_mul(k, n);
+
+    // We should now have res_s = k_n + x. Since the numbers are in unreduced form,
+    // we should handle the carry.
+
+    tempvar carry1 = (res_s.d0 - k_n.d0 - x.d0) / BASE;
+    assert [range_check_ptr + 0] = carry1 + 2 ** 127;
+
+    tempvar carry2 = (res_s.d1 - k_n.d1 - x.d1 + carry1) / BASE;
+    assert [range_check_ptr + 1] = carry2 + 2 ** 127;
+
+    tempvar carry3 = (res_s.d2 - k_n.d2 - x.d2 + carry2) / BASE;
+    assert [range_check_ptr + 2] = carry3 + 2 ** 127;
+
+    tempvar carry4 = (res_s.d3 - k_n.d3 + carry3) / BASE;
+    assert [range_check_ptr + 3] = carry4 + 2 ** 127;
+
+    assert res_s.d4 - k_n.d4 + carry4 = 0;
+
+    let range_check_ptr = range_check_ptr + 4;
+
+    return (res=res);
+}
+
+func main{range_check_ptr} () -> (){
+    alloc_locals;
+    let bi1 = BigInt3(0x216936D3CD6E53FEC0A4E, 0x231FDD6DC5C692CC760952, 0x5A7B2C9562D608F25D51A);
+    let bi2 = BigInt3(0x666666666666666666666, 0x6666666666666666666666, 0x666666666666666666658);
+    let res = mul_s_inv(bi1, bi2);
+    assert res = res;
+    return ();
+}

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -38,7 +38,10 @@ use crate::{
                     is_zero_assign_scope_variables, is_zero_nondet, is_zero_pack, reduce,
                     verify_zero,
                 },
-                signature::{div_mod_n_packed_divmod, div_mod_n_safe_div, get_point_from_x},
+                signature::{
+                    div_mod_n_packed_divmod, div_mod_n_safe_div, get_point_from_x,
+                    pack_modn_div_modn,
+                },
             },
             segments::{relocate_segment, temporary_array},
             set::set_add,
@@ -349,7 +352,7 @@ impl HintProcessor for BuiltinHintProcessor {
                 &hint_data.ids_data,
                 &hint_data.ap_tracking,
             ),
-            hint_code::DIV_MOD_N_SAFE_DIV => div_mod_n_safe_div(exec_scopes),
+            hint_code::DIV_MOD_N_SAFE_DIV => div_mod_n_safe_div(exec_scopes, "a", "b"),
             hint_code::GET_POINT_FROM_X => get_point_from_x(
                 vm,
                 exec_scopes,
@@ -483,6 +486,10 @@ impl HintProcessor for BuiltinHintProcessor {
                 chained_ec_op_random_ec_point_hint(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }
             hint_code::RECOVER_Y => recover_y_hint(vm, &hint_data.ids_data, &hint_data.ap_tracking),
+            hint_code::PACK_MODN_DIV_MODN => {
+                pack_modn_div_modn(vm, exec_scopes, &hint_data.ids_data, &hint_data.ap_tracking)
+            }
+            hint_code::XS_SAFE_DIV => div_mod_n_safe_div(exec_scopes, "x", "s"),
             hint_code::UINT384_UNSIGNED_DIV_REM => {
                 uint384_unsigned_div_rem(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -662,6 +662,15 @@ from starkware.python.math_utils import recover_y
 ids.p.x = ids.x
 # This raises an exception if `x` is not on the curve.
 ids.p.y = recover_y(ids.x, ALPHA, BETA, FIELD_PRIME)";
+pub(crate) const PACK_MODN_DIV_MODN: &str =
+    "from starkware.cairo.common.cairo_secp.secp_utils import pack
+from starkware.python.math_utils import div_mod, safe_div
+
+N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
+x = pack(ids.x, PRIME) % N
+s = pack(ids.s, PRIME) % N
+value = res = div_mod(x, s, N)";
+pub(crate) const XS_SAFE_DIV: &str = "value = k = safe_div(res * s - x, N)";
 
 // The following hints support the lib https://github.com/NethermindEth/research-basic-Cairo-operations-big-integers/blob/main/lib/uint384.cairo
 pub const UINT384_UNSIGNED_DIV_REM: &str = "def split(num: int, num_bits_shift: int, length: int):

src/hint_processor/builtin_hint_processor/secp/signature.rs

@@ -50,9 +50,13 @@ pub fn div_mod_n_packed_divmod(
 
 // Implements hint:
 // value = k = safe_div(res * b - a, N)
-pub fn div_mod_n_safe_div(exec_scopes: &mut ExecutionScopes) -> Result<(), HintError> {
-    let a = exec_scopes.get_ref::<BigInt>("a")?;
-    let b = exec_scopes.get_ref::<BigInt>("b")?;
+pub fn div_mod_n_safe_div(
+    exec_scopes: &mut ExecutionScopes,
+    a_alias: &str,
+    b_alias: &str,
+) -> Result<(), HintError> {
+    let a = exec_scopes.get_ref::<BigInt>(a_alias)?;
+    let b = exec_scopes.get_ref::<BigInt>(b_alias)?;
     let res = exec_scopes.get_ref::<BigInt>("res")?;
 
     let value = safe_div_bigint(&(res * b - a), &N)?;
@@ -103,6 +107,31 @@ pub fn get_point_from_x(
     exec_scopes.insert_value("value", y);
     Ok(())
 }
+/* Implements hint:
+    from starkware.cairo.common.cairo_secp.secp_utils import pack
+    from starkware.python.math_utils import div_mod, safe_div
+
+    N = 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141
+    x = pack(ids.x, PRIME) % N
+    s = pack(ids.s, PRIME) % N
+    value = res = div_mod(x, s, N)
+*/
+pub fn pack_modn_div_modn(
+    vm: &mut VirtualMachine,
+    exec_scopes: &mut ExecutionScopes,
+    ids_data: &HashMap<String, HintReference>,
+    ap_tracking: &ApTracking,
+) -> Result<(), HintError> {
+    let x = pack(BigInt3::from_var_name("x", vm, ids_data, ap_tracking)?).mod_floor(&N);
+    let s = pack(BigInt3::from_var_name("s", vm, ids_data, ap_tracking)?).mod_floor(&N);
+
+    let value = div_mod(&x, &s, &N);
+    exec_scopes.insert_value("x", x);
+    exec_scopes.insert_value("s", s);
+    exec_scopes.insert_value("value", value.clone());
+    exec_scopes.insert_value("res", value);
+    Ok(())
+}
 
 #[cfg(test)]
 mod tests {
@@ -147,7 +176,7 @@ mod tests {
         let ids_data = non_continuous_ids_data![("a", -3), ("b", 0)];
         let mut exec_scopes = ExecutionScopes::new();
         assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Ok(()));
-        assert_matches!(div_mod_n_safe_div(&mut exec_scopes), Ok(()));
+        assert_matches!(div_mod_n_safe_div(&mut exec_scopes, "a", "b"), Ok(()));
     }
 
     #[test]
@@ -161,6 +190,8 @@ mod tests {
         assert_matches!(
             div_mod_n_safe_div(
                 &mut exec_scopes,
+                "a",
+                "b"
             ),
             Err(
                 HintError::Math(MathError::SafeDivFailBigInt(
@@ -238,4 +269,25 @@ mod tests {
             )]
         );
     }
+
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn pack_modn_div_modn_ok() {
+        let hint_code = hint_code::PACK_MODN_DIV_MODN;
+        let mut vm = vm!();
+
+        vm.segments = segments![
+            ((1, 0), 15),
+            ((1, 1), 3),
+            ((1, 2), 40),
+            ((1, 3), 0),
+            ((1, 4), 10),
+            ((1, 5), 1)
+        ];
+        vm.run_context.fp = 3;
+        let ids_data = non_continuous_ids_data![("x", -3), ("s", 0)];
+        let mut exec_scopes = ExecutionScopes::new();
+        assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Ok(()));
+        assert_matches!(div_mod_n_safe_div(&mut exec_scopes, "x", "s"), Ok(()));
+    }
 }

src/tests/cairo_run_test.rs

@@ -1281,6 +1281,13 @@ fn cairo_run_is_quad_residue_test() {
     run_program_simple(program_data.as_slice());
 }
 
+#[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn cairo_run_mul_s_inv() {
+    let program_data = include_bytes!("../../cairo_programs/mul_s_inv.json");
+    run_program_simple(program_data.as_slice());
+}
+
 #[test]
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
 fn cairo_run_keccak_alternative_hint() {