Secp p hints

cairo_programs/ec_double_slope.cairo

@@ -0,0 +1,212 @@
+%builtins range_check
+
+// Source: https://github.com/rdubois-crypto/efficient-secp256r1/blob/4b74807c5e91f1ed4cb00a1c973be05c63986e61/src/secp256r1/ec.cairo
+from starkware.cairo.common.cairo_secp.bigint import BigInt3, UnreducedBigInt3, nondet_bigint3
+from starkware.cairo.common.cairo_secp.ec import EcPoint
+
+// src.secp256r1.constants
+// SECP_REM is defined by the equation:
+//   secp256r1_prime = 2 ** 256 - SECP_REM.
+const SECP_REM = 2 ** 224 - 2 ** 192 - 2 ** 96 + 1;
+
+const BASE = 2 ** 86;
+
+// A =  0xffffffff00000001000000000000000000000000fffffffffffffffffffffffc
+const A0 = 0x3ffffffffffffffffffffc;
+const A1 = 0x3ff;
+const A2 = 0xffffffff0000000100000;
+
+// Constants for unreduced_mul/sqr
+const s2 = (-(2 ** 76)) - 2 ** 12;
+const s1 = (-(2 ** 66)) + 4;
+const s0 = 2 ** 56;
+
+const r2 = 2 ** 54 - 2 ** 22;
+const r1 = -(2 ** 12);
+const r0 = 4;
+
+// src.secp256r1.field
+// Adapt from starkware.cairo.common.math's assert_250_bit
+func assert_165_bit{range_check_ptr}(value) {
+    const UPPER_BOUND = 2 ** 165;
+    const SHIFT = 2 ** 128;
+    const HIGH_BOUND = UPPER_BOUND / SHIFT;
+
+    let low = [range_check_ptr];
+    let high = [range_check_ptr + 1];
+
+    %{
+        from starkware.cairo.common.math_utils import as_int
+
+        # Correctness check.
+        value = as_int(ids.value, PRIME) % PRIME
+        assert value < ids.UPPER_BOUND, f'{value} is outside of the range [0, 2**250).'
+
+        # Calculation for the assertion.
+        ids.high, ids.low = divmod(ids.value, ids.SHIFT)
+    %}
+
+    assert [range_check_ptr + 2] = HIGH_BOUND - 1 - high;
+
+    assert value = high * SHIFT + low;
+
+    let range_check_ptr = range_check_ptr + 3;
+    return ();
+}
+
+// src.secp256r1.field
+// Computes the multiplication of two big integers, given in BigInt3 representation, modulo the
+// secp256r1 prime.
+//
+// Arguments:
+//   x, y - the two BigInt3 to operate on.
+//
+// Returns:
+//   x * y in an UnreducedBigInt3 representation (the returned limbs may be above 3 * BASE).
+//
+// This means that if unreduced_mul is called on the result of nondet_bigint3, or the difference
+// between two such results, we have:
+//   Soundness guarantee: the limbs are in the range ().
+//   Completeness guarantee: the limbs are in the range ().
+func unreduced_mul(a: BigInt3, b: BigInt3) -> (res_low: UnreducedBigInt3) {
+    tempvar twice_d2 = a.d2 * b.d2;
+    tempvar d1d2 = a.d2 * b.d1 + a.d1 * b.d2;
+    return (
+        UnreducedBigInt3(
+            d0=a.d0 * b.d0 + s0 * twice_d2 + r0 * d1d2,
+            d1=a.d1 * b.d0 + a.d0 * b.d1 + s1 * twice_d2 + r1 * d1d2,
+            d2=a.d2 * b.d0 + a.d1 * b.d1 + a.d0 * b.d2 + s2 * twice_d2 + r2 * d1d2,
+        ),
+    );
+}
+
+// src.secp256r1.field
+// Computes the square of a big integer, given in BigInt3 representation, modulo the
+// secp256r1 prime.
+//
+// Has the same guarantees as in unreduced_mul(a, a).
+func unreduced_sqr(a: BigInt3) -> (res_low: UnreducedBigInt3) {
+    tempvar twice_d2 = a.d2 * a.d2;
+    tempvar twice_d1d2 = a.d2 * a.d1 + a.d1 * a.d2;
+    tempvar d1d0 = a.d1 * a.d0;
+    return (
+        UnreducedBigInt3(
+            d0=a.d0 * a.d0 + s0 * twice_d2 + r0 * twice_d1d2,
+            d1=d1d0 + d1d0 + s1 * twice_d2 + r1 * twice_d1d2,
+            d2=a.d2 * a.d0 + a.d1 * a.d1 + a.d0 * a.d2 + s2 * twice_d2 + r2 * twice_d1d2,
+        ),
+    );
+}
+
+// src.secp256r1.field
+// Verifies that the given unreduced value is equal to zero modulo the secp256r1 prime.
+//
+// Completeness assumption: val's limbs are in the range (-2**210.99, 2**210.99).
+// Soundness assumption: val's limbs are in the range (-2**250, 2**250).
+func verify_zero{range_check_ptr}(val: UnreducedBigInt3) {
+    alloc_locals;
+    local q;
+    // local q_sign;
+    let q_sign = 1;
+    // original:
+    // %{ from starkware.cairo.common.cairo_secp.secp_utils import SECP256R1_P as SECP_P %}
+    // %{
+    //     from starkware.cairo.common.cairo_secp.secp_utils import pack
+
+    // q, r = divmod(pack(ids.val, PRIME), SECP_P)
+    //     assert r == 0, f"verify_zero: Invalid input {ids.val.d0, ids.val.d1, ids.val.d2}."
+    //     if q >= 0:
+    //         ids.q = q % PRIME
+    //         ids.q_sign = 1
+    //     else:
+    //         ids.q = (0-q) % PRIME
+    //         ids.q_sign = -1 % PRIME
+    // %}
+    %{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_P as SECP_P %}
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+
+        q, r = divmod(pack(ids.val, PRIME), SECP_P)
+        assert r == 0, f"verify_zero: Invalid input {ids.val.d0, ids.val.d1, ids.val.d2}."
+        ids.q = q % PRIME
+    %}
+    // assert_250_bit(q); // 256K steps
+    // assert_le_felt(q, 2**165); // 275K steps
+    assert_165_bit(q);
+    assert q_sign * (val.d2 + val.d1 / BASE + val.d0 / BASE ** 2) = q * (
+        (BASE / 4) - SECP_REM / BASE ** 2
+    );
+    // Multiply by BASE**2 both sides:
+    //  (q_sign) * val = q * (BASE**3 / 4 - SECP_REM)
+    //            = q * (2**256 - SECP_REM) = q * secp256r1_prime = 0 mod secp256r1_prime
+    return ();
+}
+
+// Computes the slope of the elliptic curve at a given point.
+// The slope is used to compute point + point.
+//
+// Arguments:
+//   point - the point to operate on.
+//
+// Returns:
+//   slope - the slope of the curve at point, in BigInt3 representation.
+//
+// Assumption: point != 0.
+func compute_doubling_slope{range_check_ptr}(point: EcPoint) -> (slope: BigInt3) {
+    // Note that y cannot be zero: assume that it is, then point = -point, so 2 * point = 0, which
+    // contradicts the fact that the size of the curve is odd.
+    // originals:
+    // %{ from starkware.cairo.common.cairo_secp.secp_utils import SECP256R1_P as SECP_P %}
+    // %{ from starkware.cairo.common.cairo_secp.secp_utils import SECP256R1_ALPHA as ALPHA %}
+    %{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_P as SECP_P %}
+    %{ from starkware.cairo.common.cairo_secp.secp256r1_utils import SECP256R1_ALPHA as ALPHA %}
+    %{
+        from starkware.cairo.common.cairo_secp.secp_utils import pack
+        from starkware.python.math_utils import ec_double_slope
+
+        # Compute the slope.
+        x = pack(ids.point.x, PRIME)
+        y = pack(ids.point.y, PRIME)
+        value = slope = ec_double_slope(point=(x, y), alpha=ALPHA, p=SECP_P)
+    %}
+    let (slope: BigInt3) = nondet_bigint3();
+
+    let (x_sqr: UnreducedBigInt3) = unreduced_sqr(point.x);
+    let (slope_y: UnreducedBigInt3) = unreduced_mul(slope, point.y);
+    verify_zero(
+        UnreducedBigInt3(
+            d0=3 * x_sqr.d0 + A0 - 2 * slope_y.d0,
+            d1=3 * x_sqr.d1 + A1 - 2 * slope_y.d1,
+            d2=3 * x_sqr.d2 + A2 - 2 * slope_y.d2,
+        ),
+    );
+
+    return (slope=slope);
+}
+
+func test_doubling_slope{range_check_ptr}() {
+    let point = EcPoint(BigInt3(614323, 5456867, 101208), BigInt3(773712524, 77371252, 5298795));
+
+    let (slope) = compute_doubling_slope(point);
+
+    assert slope = BigInt3(
+        64081873649130491683833713, 34843994309543177837008178, 16548672716077616016846383
+    );
+
+    let point = EcPoint(
+        BigInt3(51215, 36848548548458, 634734734), BigInt3(26362, 263724839599, 901297012)
+    );
+
+    let (slope) = compute_doubling_slope(point);
+
+    assert slope = BigInt3(
+        71848883893335852660776740, 75644451964360469099209675, 547087410329256463669633
+    );
+
+    return ();
+}
+
+func main{range_check_ptr}() {
+    test_doubling_slope();
+    return ();
+}

pkg/hints/bigint_hint.go

@@ -0,0 +1,56 @@
+package hints
+
+import (
+	"errors"
+	"math/big"
+
+	. "github.com/lambdaclass/cairo-vm.go/pkg/hints/hint_utils"
+	"github.com/lambdaclass/cairo-vm.go/pkg/lambdaworks"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/types"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/vm"
+	"github.com/lambdaclass/cairo-vm.go/pkg/vm/memory"
+)
+
+/*
+Implements hint:
+%{
+    from starkware.cairo.common.cairo_secp.secp_utils import split
+
+    segments.write_arg(ids.res.address_, split(value))
+%}
+*/
+
+func NondetBigInt3(virtual_machine VirtualMachine, execScopes ExecutionScopes, idsData IdsManager) error {
+	resRelloc, err := idsData.GetAddr("res", &virtual_machine)
+	if err != nil {
+		return err
+	}
+
+	valueUncast, err := execScopes.Get("value")
+	if err != nil {
+		return err
+	}
+	value, ok := valueUncast.(big.Int)
+	if !ok {
+		return errors.New("Could not cast value into big int")
+	}
+
+	bigint3Split, err := Bigint3Split(value)
+	if err != nil {
+		return err
+	}
+
+	arg := make([]memory.MaybeRelocatable, 0)
+
+	for i := 0; i < 3; i++ {
+		m := memory.NewMaybeRelocatableFelt(lambdaworks.FeltFromBigInt(&bigint3Split[i]))
+		arg = append(arg, *m)
+	}
+
+	_, loadErr := virtual_machine.Segments.LoadData(resRelloc, &arg)
+	if loadErr != nil {
+		return loadErr
+	}
+
+	return nil
+}

pkg/hints/bigint_hint_test.go

@@ -0,0 +1,75 @@
+package hints_test
+
+import (
+	"math/big"
+	"testing"
+
+	. "github.com/lambdaclass/cairo-vm.go/pkg/hints"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/hints/hint_codes"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/hints/hint_utils"
+	"github.com/lambdaclass/cairo-vm.go/pkg/lambdaworks"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/types"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/vm"
+	. "github.com/lambdaclass/cairo-vm.go/pkg/vm/memory"
+)
+
+func TestNonDetBigInt3Ok(t *testing.T) {
+	vm := NewVirtualMachine()
+
+	vm.Segments.AddSegment()
+	vm.Segments.AddSegment()
+	vm.Segments.AddSegment()
+
+	vm.RunContext.Pc = NewRelocatable(0, 0)
+	vm.RunContext.Ap = NewRelocatable(1, 6)
+	vm.RunContext.Fp = NewRelocatable(1, 6)
+
+	value, _ := new(big.Int).SetString("7737125245533626718119526477371252455336267181195264773712524553362", 10)
+	execScopes := NewExecutionScopes()
+
+	execScopes.AssignOrUpdateVariable("value", *value)
+
+	idsManager := SetupIdsForTest(
+		map[string][]*MaybeRelocatable{
+			"res": {nil},
+		},
+		vm,
+	)
+
+	hintProcessor := CairoVmHintProcessor{}
+	hintData := any(HintData{
+		Ids:  idsManager,
+		Code: NONDET_BIGINT3_V1,
+	})
+	err := hintProcessor.ExecuteHint(vm, &hintData, nil, execScopes)
+	if err != nil {
+		t.Errorf("Non Det Big Int 3 hint test failed with error: %s", err)
+	} else {
+		valueInStruct0, err := idsManager.GetStructFieldFelt("res", 0, vm)
+		expected0 := lambdaworks.FeltFromDecString("773712524553362")
+		if err != nil {
+			t.Errorf("error fetching from ids manager : %s", err)
+		}
+		if valueInStruct0 != expected0 {
+			t.Errorf(" Incorrect field value %s, expected %s", valueInStruct0.ToBigInt().Text(10), expected0.ToBigInt().Text(10))
+		}
+
+		valueInStruct1, err := idsManager.GetStructFieldFelt("res", 1, vm)
+		expected1 := lambdaworks.FeltFromDecString("57408430697461422066401280")
+		if err != nil {
+			t.Errorf("error fetching from ids manager : %s", err)
+		}
+		if valueInStruct1 != expected1 {
+			t.Errorf(" Incorrect field value %s, expected %s", valueInStruct1.ToBigInt().Text(10), expected1.ToBigInt().Text(10))
+		}
+
+		valueInStruct2, err := idsManager.GetStructFieldFelt("res", 2, vm)
+		expected2 := lambdaworks.FeltFromDecString("1292469707114105")
+		if err != nil {
+			t.Errorf("error fetching from ids manager : %s", err)
+		}
+		if valueInStruct2 != expected2 {
+			t.Errorf(" Incorrect field value %s, expected %s", valueInStruct2.ToBigInt().Text(10), expected2.ToBigInt().Text(10))
+		}
+	}
+}