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crypto/accumulator/lib.go

@@ -0,0 +1,204 @@
+//
+// Copyright Coinbase, Inc. All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+package accumulator
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/onsonr/hway/crypto/core/curves"
+)
+
+// dad constructs two polynomials - dA(x) and dD(x)
+// dA(y) = prod(y_A,t - y), t = 1...n
+// dD(y) = prod(y_D,t - y), t = 1...n
+func dad(values []Element, y Element) (Element, error) {
+	if values == nil || y == nil {
+		return nil, fmt.Errorf("curve, values or y should not be nil")
+	}
+
+	for _, value := range values {
+		if value == nil {
+			return nil, fmt.Errorf("some element is nil")
+		}
+	}
+
+	result := y.One()
+	if len(values) == 1 {
+		a := values[0]
+		result = a.Sub(y)
+	} else {
+		for i := 0; i < len(values); i++ {
+			temp := values[i].Sub(y)
+			result = result.Mul(temp)
+		}
+	}
+	return result, nil
+}
+
+type polynomialPoint []curves.Point
+
+// evaluate evaluates a PolynomialG1 on input x.
+func (p polynomialPoint) evaluate(x curves.Scalar) (curves.Point, error) {
+	if p == nil {
+		return nil, fmt.Errorf("p cannot be empty")
+	}
+	for i := 0; i < len(p); i++ {
+		if p[i] == nil {
+			return nil, fmt.Errorf("some coefficient in p is nil")
+		}
+	}
+
+	pp := x
+	res := p[0]
+	for i := 1; i < len(p); i++ {
+		r := p[i].Mul(pp)
+		res = res.Add(r)
+		pp = pp.Mul(x)
+	}
+	return res, nil
+}
+
+// Add adds two PolynomialG1
+func (p polynomialPoint) Add(rhs polynomialPoint) (polynomialPoint, error) {
+	maxLen := int(math.Max(float64(len(p)), float64(len(rhs))))
+
+	result := make(polynomialPoint, maxLen)
+
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		result[i] = c.Add(c.Identity())
+	}
+
+	for i, c := range rhs {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		if result[i] == nil {
+			result[i] = c.Add(c.Identity())
+		} else {
+			result[i] = result[i].Add(c)
+		}
+	}
+	return result, nil
+}
+
+// Mul for PolynomialG1 computes rhs * p, p is a polynomial, rhs is a value
+func (p polynomialPoint) Mul(rhs curves.Scalar) (polynomialPoint, error) {
+	result := make(polynomialPoint, len(p))
+
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		result[i] = c.Mul(rhs)
+	}
+
+	return result, nil
+}
+
+type polynomial []curves.Scalar
+
+// Add adds two polynomials
+func (p polynomial) Add(rhs polynomial) (polynomial, error) {
+	maxLen := int(math.Max(float64(len(p)), float64(len(rhs))))
+	result := make([]curves.Scalar, maxLen)
+
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		result[i] = c.Clone()
+	}
+
+	for i, c := range rhs {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		if result[i] == nil {
+			result[i] = c.Clone()
+		} else {
+			result[i] = result[i].Add(c)
+		}
+	}
+
+	return result, nil
+}
+
+// Sub computes p-rhs and returns
+func (p polynomial) Sub(rhs polynomial) (polynomial, error) {
+	maxLen := int(math.Max(float64(len(p)), float64(len(rhs))))
+	result := make([]curves.Scalar, maxLen)
+
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		result[i] = c.Clone()
+	}
+
+	for i, c := range rhs {
+		if c == nil {
+			return nil, fmt.Errorf("invalid coefficient at %d", i)
+		}
+		if result[i] == nil {
+			result[i] = c.Neg()
+		} else {
+			result[i] = result[i].Sub(c)
+		}
+	}
+
+	return result, nil
+}
+
+// Mul multiplies two polynomials - p * rhs
+func (p polynomial) Mul(rhs polynomial) (polynomial, error) {
+	// Check for each coefficient that should not be nil
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("coefficient in p at %d is nil", i)
+		}
+	}
+
+	for i, c := range rhs {
+		if c == nil {
+			return nil, fmt.Errorf("coefficient in rhs at %d is nil", i)
+		}
+	}
+
+	m := len(p)
+	n := len(rhs)
+
+	// Initialize the product polynomial
+	prod := make(polynomial, m+n-1)
+	for i := 0; i < len(prod); i++ {
+		prod[i] = p[0].Zero()
+	}
+
+	// Multiply two polynomials term by term
+	for i, cp := range p {
+		for j, cr := range rhs {
+			temp := cp.Mul(cr)
+			prod[i+j] = prod[i+j].Add(temp)
+		}
+	}
+	return prod, nil
+}
+
+// MulScalar computes p * rhs, where rhs is a scalar value
+func (p polynomial) MulScalar(rhs curves.Scalar) (polynomial, error) {
+	result := make(polynomial, len(p))
+	for i, c := range p {
+		if c == nil {
+			return nil, fmt.Errorf("coefficient at %d is nil", i)
+		}
+		result[i] = c.Mul(rhs)
+	}
+	return result, nil
+}