1// Copyright 2019 Google LLC 2// 3// Licensed under the Apache License, Version 2.0 (the "License"); 4// you may not use this file except in compliance with the License. 5// You may obtain a copy of the License at 6// 7// http://www.apache.org/licenses/LICENSE-2.0 8// 9// Unless required by applicable law or agreed to in writing, software 10// distributed under the License is distributed on an "AS IS" BASIS, 11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12// See the License for the specific language governing permissions and 13// limitations under the License. 14// 15//////////////////////////////////////////////////////////////////////////////// 16 17package aead 18 19import ( 20 "errors" 21 "fmt" 22 23 "google.golang.org/protobuf/proto" 24 "github.com/google/tink/go/core/registry" 25 "github.com/google/tink/go/keyset" 26 kmsepb "github.com/google/tink/go/proto/kms_envelope_go_proto" 27 tinkpb "github.com/google/tink/go/proto/tink_go_proto" 28) 29 30const ( 31 kmsEnvelopeAEADKeyVersion = 0 32 kmsEnvelopeAEADTypeURL = "type.googleapis.com/google.crypto.tink.KmsEnvelopeAeadKey" 33) 34 35// kmsEnvelopeAEADKeyManager is an implementation of KeyManager interface. 36// It generates new KMSEnvelopeAEADKey keys and produces new instances of KMSEnvelopeAEAD subtle. 37type kmsEnvelopeAEADKeyManager struct{} 38 39// Primitive creates an KMSEnvelopeAEAD subtle for the given serialized KMSEnvelopeAEADKey proto. 40func (km *kmsEnvelopeAEADKeyManager) Primitive(serializedKey []byte) (interface{}, error) { 41 if len(serializedKey) == 0 { 42 return nil, errors.New("kms_envelope_aead_key_manager: invalid key") 43 } 44 key := new(kmsepb.KmsEnvelopeAeadKey) 45 if err := proto.Unmarshal(serializedKey, key); err != nil { 46 return nil, errors.New("kms_envelope_aead_key_manager: invalid key") 47 } 48 if err := km.validateKey(key); err != nil { 49 return nil, err 50 } 51 uri := key.Params.KekUri 52 kmsClient, err := registry.GetKMSClient(uri) 53 if err != nil { 54 return nil, err 55 } 56 backend, err := kmsClient.GetAEAD(uri) 57 if err != nil { 58 return nil, errors.New("kms_envelope_aead_key_manager: invalid aead backend") 59 } 60 61 return NewKMSEnvelopeAEAD2(key.Params.DekTemplate, backend), nil 62} 63 64// NewKey creates a new key according to specification the given serialized KMSEnvelopeAEADKeyFormat. 65func (km *kmsEnvelopeAEADKeyManager) NewKey(serializedKeyFormat []byte) (proto.Message, error) { 66 if len(serializedKeyFormat) == 0 { 67 return nil, errors.New("kms_envelope_aead_key_manager: invalid key format") 68 } 69 keyFormat := new(kmsepb.KmsEnvelopeAeadKeyFormat) 70 if err := proto.Unmarshal(serializedKeyFormat, keyFormat); err != nil { 71 return nil, errors.New("kms_envelope_aead_key_manager: invalid key format") 72 } 73 dekKeyType := keyFormat.GetDekTemplate().GetTypeUrl() 74 if !isSupporedKMSEnvelopeDEK(dekKeyType) { 75 return nil, fmt.Errorf("unsupported DEK key type %s. Only Tink AEAD key types are supported with KMSEnvelopeAEAD", dekKeyType) 76 } 77 78 return &kmsepb.KmsEnvelopeAeadKey{ 79 Version: kmsEnvelopeAEADKeyVersion, 80 Params: keyFormat, 81 }, nil 82} 83 84// NewKeyData creates a new KeyData according to specification in the given serialized 85// KMSEnvelopeAEADKeyFormat. 86// It should be used solely by the key management API. 87func (km *kmsEnvelopeAEADKeyManager) NewKeyData(serializedKeyFormat []byte) (*tinkpb.KeyData, error) { 88 key, err := km.NewKey(serializedKeyFormat) 89 if err != nil { 90 return nil, err 91 } 92 serializedKey, err := proto.Marshal(key) 93 if err != nil { 94 return nil, err 95 } 96 return &tinkpb.KeyData{ 97 TypeUrl: kmsEnvelopeAEADTypeURL, 98 Value: serializedKey, 99 KeyMaterialType: tinkpb.KeyData_REMOTE, 100 }, nil 101} 102 103// DoesSupport indicates if this key manager supports the given key type. 104func (km *kmsEnvelopeAEADKeyManager) DoesSupport(typeURL string) bool { 105 return typeURL == kmsEnvelopeAEADTypeURL 106} 107 108// TypeURL returns the key type of keys managed by this key manager. 109func (km *kmsEnvelopeAEADKeyManager) TypeURL() string { 110 return kmsEnvelopeAEADTypeURL 111} 112 113// validateKey validates the given KmsEnvelopeAeadKey. 114func (km *kmsEnvelopeAEADKeyManager) validateKey(key *kmsepb.KmsEnvelopeAeadKey) error { 115 err := keyset.ValidateKeyVersion(key.Version, kmsEnvelopeAEADKeyVersion) 116 if err != nil { 117 return fmt.Errorf("kms_envelope_aead_key_manager: %s", err) 118 } 119 dekKeyType := key.GetParams().GetDekTemplate().GetTypeUrl() 120 if !isSupporedKMSEnvelopeDEK(dekKeyType) { 121 return fmt.Errorf("unsupported DEK key type %s. Only Tink AEAD key types are supported with KMSEnvelopeAEAD", dekKeyType) 122 } 123 return nil 124} 125