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// Copyright 2018 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ed25519
import (
"crypto/ed25519"
"fmt"
"google.golang.org/protobuf/proto"
"github.com/tink-crypto/tink-go/v2/internal/internalapi"
"github.com/tink-crypto/tink-go/v2/internal/protoserialization"
"github.com/tink-crypto/tink-go/v2/keyset"
ed25519pb "github.com/tink-crypto/tink-go/v2/proto/ed25519_go_proto"
tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto"
)
const (
verifierKeyVersion = 0
verifierTypeURL = "type.googleapis.com/google.crypto.tink.Ed25519PublicKey"
)
// verifierKeyManager is an implementation of KeyManager interface.
// It doesn't support key generation.
type verifierKeyManager struct{}
// Primitive creates a [subtle.ED25519Verifier] for the given serialized
// [ed25519pb.Ed25519PublicKey] proto.
func (km *verifierKeyManager) Primitive(serializedKey []byte) (any, error) {
keySerialization, err := protoserialization.NewKeySerialization(&tinkpb.KeyData{
TypeUrl: verifierTypeURL,
Value: serializedKey,
KeyMaterialType: tinkpb.KeyData_ASYMMETRIC_PUBLIC,
}, tinkpb.OutputPrefixType_RAW, 0)
if err != nil {
return nil, err
}
key, err := protoserialization.ParseKey(keySerialization)
if err != nil {
return nil, err
}
verifierKey, ok := key.(*PublicKey)
if !ok {
return nil, fmt.Errorf("ed25519_verifier_key_manager: invalid key type: got %T, want %T", key, (*PublicKey)(nil))
}
return NewVerifier(verifierKey, internalapi.Token{})
}
// NewKey is not implemented.
func (km *verifierKeyManager) NewKey(serializedKeyFormat []byte) (proto.Message, error) {
return nil, fmt.Errorf("ed25519_verifier_key_manager: not implemented")
}
// NewKeyData creates a new KeyData according to specification in the given
// serialized ED25519KeyFormat. It should be used solely by the key management
// API.
func (km *verifierKeyManager) NewKeyData(serializedKeyFormat []byte) (*tinkpb.KeyData, error) {
return nil, fmt.Errorf("ed25519_verifier_key_manager: not implemented")
}
// DoesSupport indicates if this key manager supports the given key type.
func (km *verifierKeyManager) DoesSupport(typeURL string) bool {
return typeURL == verifierTypeURL
}
// TypeURL returns the key type of keys managed by this key manager.
func (km *verifierKeyManager) TypeURL() string { return verifierTypeURL }
// validateKey validates the given [ed25519pb.Ed25519PublicKey].
func (km *verifierKeyManager) validateKey(key *ed25519pb.Ed25519PublicKey) error {
if err := keyset.ValidateKeyVersion(key.Version, verifierKeyVersion); err != nil {
return err
}
if len(key.KeyValue) != ed25519.PublicKeySize {
return fmt.Errorf("ed25519_verifier_key_manager: invalid key length, required :%d", ed25519.PublicKeySize)
}
return nil
}
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