1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
// 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 signature
import (
"bytes"
"fmt"
"slices"
"github.com/tink-crypto/tink-go/v2/internal/internalapi"
"github.com/tink-crypto/tink-go/v2/internal/internalregistry"
"github.com/tink-crypto/tink-go/v2/internal/monitoringutil"
"github.com/tink-crypto/tink-go/v2/internal/prefixmap"
"github.com/tink-crypto/tink-go/v2/internal/primitiveset"
"github.com/tink-crypto/tink-go/v2/internal/protoserialization"
"github.com/tink-crypto/tink-go/v2/keyset"
"github.com/tink-crypto/tink-go/v2/monitoring"
"github.com/tink-crypto/tink-go/v2/tink"
tinkpb "github.com/tink-crypto/tink-go/v2/proto/tink_go_proto"
)
// NewVerifier returns a Verifier primitive from the given keyset handle.
func NewVerifier(handle *keyset.Handle) (tink.Verifier, error) {
ps, err := keyset.Primitives[tink.Verifier](handle, internalapi.Token{})
if err != nil {
return nil, fmt.Errorf("verifier_factory: cannot obtain primitive set: %s", err)
}
return newWrappedVerifier(ps)
}
// verifierSet is a Verifier implementation that uses the
// underlying primitive set for verifying.
type wrappedVerifier struct {
verifiers *prefixmap.PrefixMap[verifierAndID]
logger monitoring.Logger
}
type verifierAndID struct {
verifier tink.Verifier
keyID uint32
}
func (a *verifierAndID) Verify(signatureBytes, data []byte) error {
return a.verifier.Verify(signatureBytes, data)
}
// Asserts that verifierSet implements the Verifier interface.
var _ tink.Verifier = (*wrappedVerifier)(nil)
type fullVerifierAdapter struct {
primitive tink.Verifier
prefix []byte
outputPrefixType tinkpb.OutputPrefixType
}
var _ tink.Verifier = (*fullVerifierAdapter)(nil)
func (a *fullVerifierAdapter) Verify(signatureBytes, data []byte) error {
if !bytes.HasPrefix(signatureBytes, a.prefix) {
return fmt.Errorf("verifier_factory: invalid signature prefix")
}
message := data
if a.outputPrefixType == tinkpb.OutputPrefixType_LEGACY {
message = slices.Concat(message, []byte{0})
}
return a.primitive.Verify(signatureBytes[len(a.prefix):], message)
}
// extractFullVerifier returns a [tink.Verifier] from the given entry as a
// "full" primitive.
//
// It wraps legacy primitives in a full primitive adapter.
func extractFullVerifier(e *primitiveset.Entry[tink.Verifier]) (tink.Verifier, error) {
if e.FullPrimitive != nil {
return e.FullPrimitive, nil
}
protoKey, err := protoserialization.SerializeKey(e.Key)
if err != nil {
return nil, err
}
prefixType := protoKey.OutputPrefixType()
return &fullVerifierAdapter{
primitive: e.Primitive,
prefix: e.OutputPrefix(),
outputPrefixType: prefixType,
}, nil
}
func newWrappedVerifier(ps *primitiveset.PrimitiveSet[tink.Verifier]) (*wrappedVerifier, error) {
verifiers := prefixmap.New[verifierAndID]()
for _, entries := range ps.Entries {
for _, e := range entries {
verifier, err := extractFullVerifier(e)
if err != nil {
return nil, err
}
verifiers.Insert(string(e.OutputPrefix()), verifierAndID{
verifier: verifier,
keyID: e.KeyID,
})
}
}
logger, err := createVerifierLogger(ps)
if err != nil {
return nil, err
}
return &wrappedVerifier{
verifiers: verifiers,
logger: logger,
}, nil
}
func createVerifierLogger(ps *primitiveset.PrimitiveSet[tink.Verifier]) (monitoring.Logger, error) {
// only keysets which contain annotations are monitored.
if len(ps.Annotations) == 0 {
return &monitoringutil.DoNothingLogger{}, nil
}
keysetInfo, err := monitoringutil.KeysetInfoFromPrimitiveSet(ps)
if err != nil {
return nil, err
}
return internalregistry.GetMonitoringClient().NewLogger(&monitoring.Context{
KeysetInfo: keysetInfo,
Primitive: "public_key_verify",
APIFunction: "verify",
})
}
// Verify checks whether the given signature is a valid signature of the given data.
func (v *wrappedVerifier) Verify(signature, data []byte) error {
it := v.verifiers.PrimitivesMatchingPrefix(signature)
for verifier, ok := it.Next(); ok; verifier, ok = it.Next() {
if err := verifier.Verify(signature, data); err != nil {
continue
}
v.logger.Log(verifier.keyID, len(data))
return nil
}
v.logger.LogFailure()
return fmt.Errorf("verifier_factory: invalid signature")
}
|
