Add Scalar.SetUInt64, remove Scalar.SetBigInt, add Hex() and DecodeHe… (

#57) * Add Scalar.SetUInt64, remove Scalar.SetBigInt, add Hex() and DecodeHex(), add tests --------- Signed-off-by: bytemare <[email protected]>
bytemare · Jun 10, 2024 · cd6020a · cd6020a
1 parent 4ef5e74
commit cd6020a
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Showing 24 changed files with 456 additions and 165 deletions.
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -120,8 +120,8 @@ jobs:
           SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }}
         with:
           args: >
-            -Dsonar.projectKey=bytemare_crypto
-            -Dsonar.organization=bytemare-github
+            -Dsonar.projectKey=crypto
+            -Dsonar.organization=bytemare
             -Dsonar.go.coverage.reportPaths=.github/coverage.out
             -Dsonar.sources=.
             -Dsonar.test.exclusions=tests/**

diff --git a/README.md b/README.md
@@ -68,10 +68,12 @@ type Scalar interface {
     LessOrEqual(Scalar) int
     IsZero() bool
     Set(Scalar) Scalar
-    SetInt(big.Int) error
+    SetUInt64(uint64) Scalar
     Copy() Scalar
     Encode() []byte
     Decode(in []byte) error
+	Hex() string
+	HexDecode([]byte) error
     encoding.BinaryMarshaler
     encoding.BinaryUnmarshaler
 }
@@ -95,6 +97,8 @@ type Element interface {
     Encode() []byte
     XCoordinate() []byte
     Decode(data []byte) error
+    Hex() string
+    HexDecode([]byte) error
     encoding.BinaryMarshaler
     encoding.BinaryUnmarshaler
 }

diff --git a/element.go b/element.go
@@ -132,6 +132,20 @@ func (e *Element) Decode(data []byte) error {
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of e.
+func (e *Element) Hex() string {
+	return e.Element.Hex()
+}
+
+// DecodeHex sets e to the decoding of the hex encoded element.
+func (e *Element) DecodeHex(h string) error {
+	if err := e.Element.DecodeHex(h); err != nil {
+		return fmt.Errorf("element DecodeHex: %w", err)
+	}
+
+	return nil
+}
+
 // MarshalBinary returns the compressed byte encoding of the element.
 func (e *Element) MarshalBinary() ([]byte, error) {
 	dec, err := e.Element.MarshalBinary()

diff --git a/go.mod b/go.mod
@@ -6,7 +6,7 @@ require (
 	filippo.io/edwards25519 v1.1.0
 	filippo.io/nistec v0.0.3
 	github.com/bytemare/hash2curve v0.3.0
-	github.com/bytemare/secp256k1 v0.1.2
+	github.com/bytemare/secp256k1 v0.1.4
 	github.com/gtank/ristretto255 v0.1.2
 )
 

diff --git a/go.sum b/go.sum
@@ -6,8 +6,8 @@ github.com/bytemare/hash v0.3.0 h1:RqFMt3mqpF7UxLdjBrsOZm/2cz0cQiAOnYc9gDLopWE=
 github.com/bytemare/hash v0.3.0/go.mod h1:YKOBchL0l8hRLFinVCL8YUKokGNIMhrWEHPHo3EV7/M=
 github.com/bytemare/hash2curve v0.3.0 h1:41Npcbc+u/E252A5aCMtxDcz7JPkkX1QzShneTFm4eg=
 github.com/bytemare/hash2curve v0.3.0/go.mod h1:itj45U8uqvCtWC0eCswIHVHswXcEHkpFui7gfJdPSfQ=
-github.com/bytemare/secp256k1 v0.1.2 h1:aM+p/+0y1h0SZWqS/yzjGPzffVFubJvwLjUgodFEWOo=
-github.com/bytemare/secp256k1 v0.1.2/go.mod h1:Pxb9miDs8PTt5mOktvvXiRflvLxI1wdxbXrc6IYsaho=
+github.com/bytemare/secp256k1 v0.1.4 h1:6F1yP6RiUiWwH7AsGHsHktmHm24QcetdDcc39roBd2M=
+github.com/bytemare/secp256k1 v0.1.4/go.mod h1:Pxb9miDs8PTt5mOktvvXiRflvLxI1wdxbXrc6IYsaho=
 github.com/gtank/ristretto255 v0.1.2 h1:JEqUCPA1NvLq5DwYtuzigd7ss8fwbYay9fi4/5uMzcc=
 github.com/gtank/ristretto255 v0.1.2/go.mod h1:Ph5OpO6c7xKUGROZfWVLiJf9icMDwUeIvY4OmlYW69o=
 golang.org/x/crypto v0.22.0 h1:g1v0xeRhjcugydODzvb3mEM9SQ0HGp9s/nh3COQ/C30=

diff --git a/internal/edwards25519/element.go b/internal/edwards25519/element.go
@@ -9,6 +9,7 @@
 package edwards25519
 
 import (
+	"encoding/hex"
 	"fmt"
 
 	ed "filippo.io/edwards25519"
@@ -163,6 +164,21 @@ func (e *Element) Decode(data []byte) error {
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of e.
+func (e *Element) Hex() string {
+	return hex.EncodeToString(e.Encode())
+}
+
+// DecodeHex sets e to the decoding of the hex encoded element.
+func (e *Element) DecodeHex(h string) error {
+	b, err := hex.DecodeString(h)
+	if err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	return e.Decode(b)
+}
+
 // MarshalBinary returns the compressed byte encoding of the element.
 func (e *Element) MarshalBinary() (data []byte, err error) {
 	return e.Encode(), nil

diff --git a/internal/edwards25519/scalar.go b/internal/edwards25519/scalar.go
@@ -9,6 +9,8 @@
 package edwards25519
 
 import (
+	"encoding/binary"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 
@@ -268,18 +270,20 @@ func (s *Scalar) Set(scalar internal.Scalar) internal.Scalar {
 	return s
 }
 
-// SetInt sets s to i modulo the field order, and returns an error if one occurs.
-func (s *Scalar) SetInt(i *big.Int) error {
-	a := new(big.Int).Set(i)
+// SetUInt64 sets s to i modulo the field order, and returns an error if one occurs.
+func (s *Scalar) SetUInt64(i uint64) internal.Scalar {
+	encoded := make([]byte, canonicalEncodingLength)
+	binary.LittleEndian.PutUint64(encoded, i)
 
-	bytes := make([]byte, 32)
-	bytes = a.Mod(a, &order).FillBytes(bytes)
-
-	for j, k := 0, len(bytes)-1; j < k; j, k = j+1, k-1 {
-		bytes[j], bytes[k] = bytes[k], bytes[j]
+	sc, err := decodeScalar(encoded)
+	if err != nil {
+		// This cannot happen, since any uint64 is smaller than the order.
+		panic(fmt.Sprintf("unexpected decoding of uint64 scalar: %s", err))
 	}
 
-	return s.Decode(bytes)
+	s.set(sc)
+
+	return s
 }
 
 func (s *Scalar) copy() *Scalar {
@@ -325,6 +329,21 @@ func (s *Scalar) Decode(in []byte) error {
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of s.
+func (s *Scalar) Hex() string {
+	return hex.EncodeToString(s.Encode())
+}
+
+// DecodeHex sets s to the decoding of the hex encoded scalar.
+func (s *Scalar) DecodeHex(h string) error {
+	b, err := hex.DecodeString(h)
+	if err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	return s.Decode(b)
+}
+
 // MarshalBinary returns the compressed byte encoding of the scalar.
 func (s *Scalar) MarshalBinary() (data []byte, err error) {
 	return s.Encode(), nil

diff --git a/internal/element.go b/internal/element.go
@@ -9,7 +9,9 @@
 // Package internal defines simple and abstract APIs to group Elements and Scalars.
 package internal
 
-import "encoding"
+import (
+	"encoding"
+)
 
 // Element interface abstracts common operations on an Element in a prime-order Group.
 type Element interface {
@@ -55,6 +57,12 @@ type Element interface {
 	// Decode sets the receiver to a decoding of the input data, and returns an error on failure.
 	Decode(data []byte) error
 
+	// Hex returns the fixed-sized hexadecimal encoding of e.
+	Hex() string
+
+	// DecodeHex sets e to the decoding of the hex encoded element.
+	DecodeHex(h string) error
+
 	// BinaryMarshaler implementation.
 	encoding.BinaryMarshaler
 

diff --git a/internal/misc.go b/internal/misc.go
@@ -10,6 +10,7 @@ package internal
 
 import (
 	cryptorand "crypto/rand"
+	"encoding"
 	"errors"
 	"fmt"
 )
@@ -52,6 +53,30 @@ var (
 	ErrParamScalarInvalidEncoding = errors.New("invalid scalar encoding")
 )
 
+// An Encoder can encode itself to machine or human-readable forms.
+type Encoder interface {
+	// Encode returns the compressed byte encoding.
+	Encode() []byte
+
+	// Hex returns the fixed-sized hexadecimal encoding.
+	Hex() string
+
+	// BinaryMarshaler implementation.
+	encoding.BinaryMarshaler
+}
+
+// A Decoder can encode itself to machine or human-readable forms.
+type Decoder interface {
+	// Decode sets the receiver to a decoding of the input data, and returns an error on failure.
+	Decode(data []byte) error
+
+	// DecodeHex sets the receiver to the decoding of the hex encoded input.
+	DecodeHex(h string) error
+
+	// BinaryUnmarshaler implementation.
+	encoding.BinaryUnmarshaler
+}
+
 // RandomBytes returns random bytes of length len (wrapper for crypto/rand).
 func RandomBytes(length int) []byte {
 	random := make([]byte, length)

diff --git a/internal/nist/element.go b/internal/nist/element.go
@@ -10,6 +10,7 @@ package nist
 
 import (
 	"crypto/subtle"
+	"encoding/hex"
 	"fmt"
 
 	"github.com/bytemare/crypto/internal"
@@ -214,12 +215,27 @@ func (e *Element[P]) XCoordinate() []byte {
 // Decode sets the receiver to a decoding of the input data, and returns an error on failure.
 func (e *Element[P]) Decode(data []byte) error {
 	if _, err := e.p.SetBytes(data); err != nil {
-		return fmt.Errorf("nist element Decode: %w", err)
+		return fmt.Errorf("%w", err)
 	}
 
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of e.
+func (e *Element[P]) Hex() string {
+	return hex.EncodeToString(e.Encode())
+}
+
+// DecodeHex sets e to the decoding of the hex encoded element.
+func (e *Element[P]) DecodeHex(h string) error {
+	b, err := hex.DecodeString(h)
+	if err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	return e.Decode(b)
+}
+
 // MarshalBinary returns the compressed byte encoding of the element.
 func (e *Element[P]) MarshalBinary() ([]byte, error) {
 	return e.Encode(), nil

diff --git a/internal/nist/scalar.go b/internal/nist/scalar.go
@@ -10,6 +10,7 @@ package nist
 
 import (
 	"crypto/subtle"
+	"encoding/hex"
 	"fmt"
 	"math/big"
 
@@ -112,7 +113,7 @@ func (s *Scalar) Pow(scalar internal.Scalar) internal.Scalar {
 		return s.One()
 	}
 
-	if scalar.Equal(scalar.Copy().One()) == 1 {
+	if scalar.Equal(newScalar(s.field).One()) == 1 {
 		return s
 	}
 
@@ -181,12 +182,10 @@ func (s *Scalar) Set(scalar internal.Scalar) internal.Scalar {
 	return s
 }
 
-// SetInt sets s to i modulo the field order, and returns an error if one occurs.
-func (s *Scalar) SetInt(i *big.Int) error {
-	s.scalar.Set(i)
-	s.field.Mod(&s.scalar)
-
-	return nil
+// SetUInt64 sets s to i modulo the field order, and returns an error if one occurs.
+func (s *Scalar) SetUInt64(i uint64) internal.Scalar {
+	s.scalar.SetUint64(i)
+	return s
 }
 
 // Copy returns a copy of the Scalar.
@@ -233,6 +232,21 @@ func (s *Scalar) Decode(in []byte) error {
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of s.
+func (s *Scalar) Hex() string {
+	return hex.EncodeToString(s.Encode())
+}
+
+// DecodeHex sets s to the decoding of the hex encoded scalar.
+func (s *Scalar) DecodeHex(h string) error {
+	b, err := hex.DecodeString(h)
+	if err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	return s.Decode(b)
+}
+
 // MarshalBinary returns the compressed byte encoding of the scalar.
 func (s *Scalar) MarshalBinary() ([]byte, error) {
 	return s.Encode(), nil

diff --git a/internal/ristretto/element.go b/internal/ristretto/element.go
@@ -10,6 +10,7 @@
 package ristretto
 
 import (
+	"encoding/hex"
 	"fmt"
 
 	"github.com/gtank/ristretto255"
@@ -169,6 +170,21 @@ func (e *Element) Decode(data []byte) error {
 	return nil
 }
 
+// Hex returns the fixed-sized hexadecimal encoding of e.
+func (e *Element) Hex() string {
+	return hex.EncodeToString(e.Encode())
+}
+
+// DecodeHex sets e to the decoding of the hex encoded element.
+func (e *Element) DecodeHex(h string) error {
+	b, err := hex.DecodeString(h)
+	if err != nil {
+		return fmt.Errorf("%w", err)
+	}
+
+	return e.Decode(b)
+}
+
 // MarshalBinary returns the compressed byte encoding of the element.
 func (e *Element) MarshalBinary() ([]byte, error) {
 	return e.Encode(), nil