Newhint#17 & Newhint#18 imports of SECP256R1_ALPHA and SECP256R1_N

CHANGELOG.md

@@ -354,6 +354,19 @@ Add missing hint on vrf.json lib [#1053](https://github.com/lambdaclass/cairo-rs
   * Remove duplicated tests in cairo_run_test
   * BREAKING CHANGE: `MemorySegmentManager.get_memory_holes` now also receives the amount of builtins in the vm. Signature is now `pub fn get_memory_holes(&self, builtin_count: usize) -> Result<usize, MemoryError>`
 
+* Add missing hints on cairo_secp lib [#1026](https://github.com/lambdaclass/cairo-rs/pull/1026):
+
+    `BuiltinHintProcessor` now supports the following hints:
+
+    ```python
+    from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_ALPHA as ALPHA
+    ```
+    and:
+
+    ```python
+    from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_N as N
+    ```
+
 * Add missing hint on vrf.json lib [#1043](https://github.com/lambdaclass/cairo-rs/pull/1043):
 
     `BuiltinHintProcessor` now supports the following hint:

cairo_programs/secp256r1_div_mod_n.cairo

@@ -0,0 +1,75 @@
+%builtins range_check
+
+// Sources: https://github.com/myBraavos/efficient-secp256r1/blob/main/src/secp256r1/signature.cairo#L48
+// Sources: https://github.com/myBraavos/efficient-secp256r1/blob/main/src/secp256r1/ec.cairo#L32
+
+from starkware.cairo.common.cairo_secp.bigint import BigInt3, nondet_bigint3, BASE, bigint_mul
+
+// N = 0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551
+const N0 = 0x179e84f3b9cac2fc632551;
+const N1 = 0x3ffffffffffef39beab69c;
+const N2 = 0xffffffff00000000fffff;
+
+func div_mod_n{range_check_ptr}(a: BigInt3, b: BigInt3) -> (res: BigInt3) {
+    %{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_N as N %}
+    // Hint 24
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+        from starkware.python.math_utils import div_mod, safe_div
+
+        a = pack(ids.a, PRIME)
+        b = pack(ids.b, PRIME)
+        value = res = div_mod(a, b, N)
+    %}
+    let (res) = nondet_bigint3();
+    // Hint 25
+    %{
+        value = k_plus_one = safe_div(res * b - a, N) + 1
+    %}
+    let (k_plus_one) = nondet_bigint3();
+    let k = BigInt3(d0=k_plus_one.d0 - 1, d1=k_plus_one.d1, d2=k_plus_one.d2);
+
+    let (res_b) = bigint_mul(res, b);
+    let n = BigInt3(N0, N1, N2);
+    let (k_n) = bigint_mul(k, n);
+
+    // We should now have res_b = k_n + a. Since the numbers are in unreduced form,
+    // we should handle the carry.
+
+    tempvar carry1 = (res_b.d0 - k_n.d0 - a.d0) / BASE;
+    assert [range_check_ptr + 0] = carry1 + 2 ** 127;
+
+    tempvar carry2 = (res_b.d1 - k_n.d1 - a.d1 + carry1) / BASE;
+    assert [range_check_ptr + 1] = carry2 + 2 ** 127;
+
+    tempvar carry3 = (res_b.d2 - k_n.d2 - a.d2 + carry2) / BASE;
+    assert [range_check_ptr + 2] = carry3 + 2 ** 127;
+
+    tempvar carry4 = (res_b.d3 - k_n.d3 + carry3) / BASE;
+    assert [range_check_ptr + 3] = carry4 + 2 ** 127;
+
+    assert res_b.d4 - k_n.d4 + carry4 = 0;
+
+    let range_check_ptr = range_check_ptr + 4;
+
+    return (res=res);
+}
+
+func test_div_mod_n{range_check_ptr: felt}() {
+    let a: BigInt3 = BigInt3(100, 99, 98);
+    let b: BigInt3 = BigInt3(10, 9, 8);
+
+    let (res) = div_mod_n(a, b);
+
+    assert res = BigInt3(
+        17710125265123803206911742, 47938808641831879622633720, 16714845192957993827873659
+    );
+
+    return ();
+}
+
+func main{range_check_ptr: felt}() {
+    test_div_mod_n();
+
+    return ();
+}

src/hint_processor/builtin_hint_processor/builtin_hint_processor_definition.rs

@@ -52,7 +52,8 @@ use crate::{
                 bigint_utils::{bigint_to_uint256, hi_max_bitlen, nondet_bigint3},
                 ec_utils::{
                     compute_doubling_slope, compute_slope, di_bit, fast_ec_add_assign_new_x,
-                    fast_ec_add_assign_new_y, import_secp256r1_p, quad_bit,
+                    fast_ec_add_assign_new_y, import_secp256r1_alpha, import_secp256r1_n,
+                    import_secp256r1_p, quad_bit,
                 },
                 field_utils::{
                     is_zero_assign_scope_variables, is_zero_assign_scope_variables_external_const,
@@ -673,6 +674,8 @@ impl HintProcessor for BuiltinHintProcessor {
             hint_code::UINT256_MUL_DIV_MOD => {
                 uint256_mul_div_mod(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }
+            hint_code::IMPORT_SECP256R1_ALPHA => import_secp256r1_alpha(exec_scopes),
+            hint_code::IMPORT_SECP256R1_N => import_secp256r1_n(exec_scopes),
             hint_code::UINT512_UNSIGNED_DIV_REM => {
                 uint512_unsigned_div_rem(vm, &hint_data.ids_data, &hint_data.ap_tracking)
             }

src/hint_processor/builtin_hint_processor/hint_code.rs

@@ -1049,6 +1049,12 @@ ids.remainder.d2 = remainder_split[2]"#;
 
 pub const UINT384_SIGNED_NN: &str = "memory[ap] = 1 if 0 <= (ids.a.d2 % PRIME) < 2 ** 127 else 0";
 
+pub const IMPORT_SECP256R1_ALPHA: &str =
+    "from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_ALPHA as ALPHA";
+
+pub const IMPORT_SECP256R1_N: &str =
+    "from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_N as N";
+
 pub const UINT384_GET_SQUARE_ROOT: &str =
     "from starkware.python.math_utils import is_quad_residue, sqrt
 

src/hint_processor/builtin_hint_processor/secp/ec_utils.rs

@@ -5,7 +5,10 @@ use crate::{
                 get_integer_from_var_name, get_relocatable_from_var_name,
                 insert_value_from_var_name, insert_value_into_ap,
             },
-            secp::{bigint_utils::BigInt3, secp_utils::SECP_P},
+            secp::{
+                bigint_utils::BigInt3,
+                secp_utils::{SECP256R1_ALPHA, SECP256R1_N, SECP_P},
+            },
         },
         hint_processor_definition::HintReference,
     },
@@ -18,6 +21,7 @@ use crate::{
 use felt::Felt252;
 use num_bigint::BigInt;
 use num_integer::Integer;
+
 use num_traits::{One, ToPrimitive, Zero};
 
 use super::secp_utils::SECP256R1_P;
@@ -333,6 +337,24 @@ pub fn ec_mul_inner(
     insert_value_into_ap(vm, scalar)
 }
 
+/*
+Implements hint:
+%{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_ALPHA as ALPHA %}
+*/
+pub fn import_secp256r1_alpha(exec_scopes: &mut ExecutionScopes) -> Result<(), HintError> {
+    exec_scopes.insert_value("ALPHA", SECP256R1_ALPHA.clone());
+    Ok(())
+}
+
+/*
+Implements hint:
+%{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_N as N %}
+*/
+pub fn import_secp256r1_n(exec_scopes: &mut ExecutionScopes) -> Result<(), HintError> {
+    exec_scopes.insert_value("N", SECP256R1_N.clone());
+    Ok(())
+}
+
 /*
 Implements hint:
 %{
@@ -435,6 +457,7 @@ mod tests {
     };
     use assert_matches::assert_matches;
 
+    use num_bigint::BigUint;
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::*;
 
@@ -1142,4 +1165,26 @@ mod tests {
         // Check hint memory inserts
         check_memory![vm.segments.memory, ((1, 3), 2)];
     }
+
+    #[test]
+    #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+    fn run_import_secp256r1_alpha() {
+        let hint_code = "from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_ALPHA as ALPHA";
+        let mut vm = vm_with_range_check!();
+
+        //Initialize fp
+        vm.run_context.fp = 1;
+        //Create hint_data
+        let ids_data = ids_data!["point"];
+        let mut exec_scopes = ExecutionScopes::new();
+        //Execute the hint
+        assert_matches!(run_hint!(vm, ids_data, hint_code, &mut exec_scopes), Ok(()));
+        //Check 'ALPHA' is defined in the vm scope
+        assert_matches!(
+            exec_scopes.get::<BigUint>("ALPHA"),
+            Ok(x) if x == biguint_str!(
+                "115792089210356248762697446949407573530086143415290314195533631308867097853948"
+            )
+        );
+    }
 }

src/hint_processor/builtin_hint_processor/secp/secp_utils.rs

@@ -61,7 +61,7 @@ lazy_static! {
         "115792089210356248762697446949407573530086143415290314195533631308867097853951"
     ).unwrap();
     //SECP256R1_N = 0xFFFFFFFF00000000FFFFFFFFFFFFFFFFBCE6FAADA7179E84F3B9CAC2FC632551
-    pub(crate) static ref SECP256R1_N: BigUint = BigUint::from_str(
+    pub(crate) static ref SECP256R1_N: BigInt = BigInt::from_str(
         "115792089210356248762697446949407573529996955224135760342422259061068512044369"
     ).unwrap();
     //SECP256R1_ALPHA = 0xFFFFFFFF00000001000000000000000000000000FFFFFFFFFFFFFFFFFFFFFFFC

src/hint_processor/builtin_hint_processor/secp/signature.rs

@@ -81,7 +81,9 @@ pub fn div_mod_n_safe_div(
     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)?.add(to_add);
+    let n = exec_scopes.get("N")?;
+
+    let value = safe_div_bigint(&(res * b - a), &n)?.add(to_add);
 
     exec_scopes.insert_value("value", value);
     Ok(())
@@ -151,6 +153,7 @@ pub fn pack_modn_div_modn(
     let value = div_mod(&x, &s, &N);
     exec_scopes.insert_value("x", x);
     exec_scopes.insert_value("s", s);
+    exec_scopes.insert_value("N", N.clone());
     exec_scopes.insert_value("value", value.clone());
     exec_scopes.insert_value("res", value);
     Ok(())
@@ -218,7 +221,8 @@ mod tests {
         let mut exec_scopes = scope![
             ("a", BigInt::zero()),
             ("b", BigInt::one()),
-            ("res", BigInt::one())
+            ("res", BigInt::one()),
+            ("N", N.clone())
         ];
         assert_matches!(
             div_mod_n_safe_div(
@@ -308,6 +312,7 @@ mod tests {
     #[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 exec_scopes = scope![("N", N.clone())];
         let mut vm = vm!();
 
         vm.segments = segments![
@@ -320,7 +325,6 @@ mod tests {
         ];
         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", 0), Ok(()));
     }

src/tests/cairo_run_test.rs

@@ -793,6 +793,13 @@ fn is_zero() {
     run_program_simple(program_data.as_slice());
 }
 
+#[test]
+#[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
+fn cairo_run_secp256r1_div_mod_n() {
+    let program_data = include_bytes!("../../cairo_programs/secp256r1_div_mod_n.json");
+    run_program_simple(program_data.as_slice());
+}
+
 #[test]
 #[cfg_attr(target_arch = "wasm32", wasm_bindgen_test)]
 fn is_zero_pack() {