Added JSONReGetGroup for JSON unmarshalling of group scalars and elem…

…ents (#3)

Signed-off-by: bytemare <[email protected]>

encoding/json.go

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MIT
+//
+// Copyright (C) 2020-2024 Daniel Bourdrez. All Rights Reserved.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree or at
+// https://spdx.org/licenses/MIT.html
+
+// Package encoding provides serde utilities.
+package encoding
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+
+	"github.com/bytemare/ecc"
+	"github.com/bytemare/ecc/internal"
+)
+
+func jsonReGetField(key, s, catch string) (string, error) {
+	r := fmt.Sprintf(`%q:%s`, key, catch)
+	re := regexp.MustCompile(r)
+	matches := re.FindStringSubmatch(s)
+
+	if len(matches) != 2 {
+		return "", internal.ErrDecodingInvalidJSONEncoding
+	}
+
+	return matches[1], nil
+}
+
+// JSONReGetGroup attempts to find the group JSON encoding in s. The optional key argument overrides the default key the
+// regex will use to look for the group.
+func JSONReGetGroup(s string, key ...string) (ecc.Group, error) {
+	reKey := "group"
+	if len(key) != 0 && key[0] != "" {
+		reKey = key[0]
+	}
+
+	f, err := jsonReGetField(reKey, s, `(\w+)`)
+	if err != nil {
+		return 0, err
+	}
+
+	i, err := strconv.Atoi(f)
+	if err != nil {
+		return 0, fmt.Errorf("failed to read Group: %w", err)
+	}
+
+	if i < 0 || i > 63 {
+		return 0, internal.ErrInvalidGroup
+	}
+
+	c := ecc.Group(i)
+	if !c.Available() {
+		return 0, internal.ErrInvalidGroup
+	}
+
+	return c, nil
+}

internal/misc.go

@@ -16,6 +16,9 @@ import (
 )
 
 var (
+	// ErrInvalidGroup indicates usage of an unavailable or invalid group.
+	ErrInvalidGroup = errors.New("invalid group")
+
 	// ErrParamNilScalar indicates a forbidden nil or empty scalar.
 	ErrParamNilScalar = errors.New("nil or empty scalar")
 
@@ -54,6 +57,12 @@ var (
 
 	// ErrUInt64TooBig indicates that the scalar is higher than the allowed values for uint64.
 	ErrUInt64TooBig = errors.New("scalar is too big to be uint64")
+
+	// ErrDecodingInvalidLength indicates an invalid encoding length.
+	ErrDecodingInvalidLength = errors.New("invalid encoding length")
+
+	// ErrDecodingInvalidJSONEncoding indicates an invalid JSON encoding.
+	ErrDecodingInvalidJSONEncoding = errors.New("invalid JSON encoding")
 )
 
 // An Encoder can encode itself to machine or human-readable forms.

tests/bench_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"bytes"

tests/element_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"encoding/hex"

tests/encoding_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"bytes"
@@ -19,6 +19,7 @@ import (
 	"testing"
 
 	"github.com/bytemare/ecc"
+	eccEncoding "github.com/bytemare/ecc/encoding"
 )
 
 type serde interface {
@@ -263,3 +264,52 @@ func TestEncoding_Hex_Fails(t *testing.T) {
 		}
 	})
 }
+
+func TestJSONReGetGroup(t *testing.T) {
+	testAllGroups(t, func(group *testGroup) {
+		test := struct {
+			Group ecc.Group `json:"group"`
+			Int   int       `json:"int"`
+		}{
+			Group: group.group,
+			Int:   1,
+		}
+
+		enc, err := json.Marshal(test)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		g, err := eccEncoding.JSONReGetGroup(string(enc))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if g != group.group {
+			t.Fatal(errExpectedEquality)
+		}
+
+		// with another key
+		test2 := struct {
+			Group ecc.Group `json:"ciphersuite"`
+			Int   int       `json:"int"`
+		}{
+			Group: group.group,
+			Int:   1,
+		}
+
+		enc, err = json.Marshal(test2)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		g, err = eccEncoding.JSONReGetGroup(string(enc), "ciphersuite")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if g != group.group {
+			t.Fatal(errExpectedEquality)
+		}
+	})
+}

tests/groups_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"encoding/hex"

tests/h2c_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"crypto/elliptic"

tests/json_test.go

@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: MIT
+//
+// Copyright (C) 2020-2024 Daniel Bourdrez. All Rights Reserved.
+//
+// This source code is licensed under the MIT license found in the
+// LICENSE file in the root directory of this source tree or at
+// https://spdx.org/licenses/MIT.html
+
+package ecc_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/bytemare/ecc"
+	eccEncoding "github.com/bytemare/ecc/encoding"
+	"github.com/bytemare/ecc/internal"
+)
+
+func replaceStringInBytes(data []byte, old, new string) []byte {
+	s := string(data)
+	s = strings.Replace(s, old, new, 1)
+
+	return []byte(s)
+}
+
+type jsonTesterBaddie struct {
+	key, value, expectedError string
+}
+
+func testJSONBaddie(in any, baddie jsonTesterBaddie) error {
+	data, err := json.Marshal(in)
+	if err != nil {
+		return err
+	}
+
+	data = replaceStringInBytes(data, baddie.key, baddie.value)
+
+	_, err = eccEncoding.JSONReGetGroup(string(data))
+
+	if len(baddie.expectedError) != 0 { // we're expecting an error
+		if err == nil ||
+			!strings.HasPrefix(err.Error(), baddie.expectedError) {
+			return fmt.Errorf("expected error %q, got %q", baddie.expectedError, err)
+		}
+	} else {
+		if err != nil {
+			return fmt.Errorf("unexpected error %q", err)
+		}
+	}
+
+	return nil
+}
+
+func jsonTester(badJSONErr string, in any) error {
+	// JSON: bad json
+	baddie := jsonTesterBaddie{
+		key:           "\"group\"",
+		value:         "bad",
+		expectedError: "invalid character 'b' looking for beginning of object key string",
+	}
+
+	if err := testJSONBaddie(in, baddie); err != nil {
+		// return err
+	}
+
+	// UnmarshallJSON: bad group
+	baddie = jsonTesterBaddie{
+		key:           "\"group\"",
+		value:         "\"group\":2, \"oldGroup\"",
+		expectedError: internal.ErrInvalidGroup.Error(),
+	}
+
+	if err := testJSONBaddie(in, baddie); err != nil {
+		return err
+	}
+
+	// UnmarshallJSON: bad ciphersuite
+	baddie = jsonTesterBaddie{
+		key:           "\"group\"",
+		value:         "\"group\":70, \"oldGroup\"",
+		expectedError: internal.ErrInvalidGroup.Error(),
+	}
+
+	if err := testJSONBaddie(in, baddie); err != nil {
+		return err
+	}
+
+	// UnmarshallJSON: bad ciphersuite
+	baddie = jsonTesterBaddie{
+		key:           "\"group\"",
+		value:         "\"group\":-1, \"oldGroup\"",
+		expectedError: badJSONErr,
+	}
+
+	if err := testJSONBaddie(in, baddie); err != nil {
+		return err
+	}
+
+	// UnmarshallJSON: bad ciphersuite
+	overflow := "9223372036854775808" // MaxInt64 + 1
+	baddie = jsonTesterBaddie{
+		key:           "\"group\"",
+		value:         "\"group\":" + overflow + ", \"oldGroup\"",
+		expectedError: "failed to read Group: strconv.Atoi: parsing \"9223372036854775808\": value out of range",
+	}
+
+	if err := testJSONBaddie(in, baddie); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func TestJSONReGetGroup_BadString(t *testing.T) {
+	testAllGroups(t, func(group *testGroup) {
+		test := struct {
+			Group ecc.Group `json:"group"`
+			Int   int       `json:"int"`
+		}{
+			Group: group.group,
+			Int:   1,
+		}
+
+		// JSON: bad json
+		errInvalidJSON := "invalid JSON encoding"
+		if err := jsonTester(errInvalidJSON, test); err != nil {
+			t.Fatal(err)
+		}
+	})
+}

tests/nist_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"crypto/elliptic"

tests/ristretto_hash_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"bytes"

tests/ristretto_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"bytes"

tests/scalar_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"bytes"

tests/table_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"crypto"

tests/utils_test.go

@@ -6,7 +6,7 @@
 // LICENSE file in the root directory of this source tree or at
 // https://spdx.org/licenses/MIT.html
 
-package group_test
+package ecc_test
 
 import (
 	"encoding/hex"