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
|
// Copyright 2020 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"
"slices"
"github.com/tink-crypto/tink-go/v2/insecuresecretdataaccess"
"github.com/tink-crypto/tink-go/v2/internal/internalapi"
"github.com/tink-crypto/tink-go/v2/key"
"github.com/tink-crypto/tink-go/v2/tink"
)
// signer is an implementation of [tink.Signer] for ED25519.
type signer struct {
privateKey ed25519.PrivateKey
prefix []byte
variant Variant
}
var _ tink.Signer = (*signer)(nil)
// NewSigner creates a new [tink.Signer] for ED25519.
//
// This is an internal API.
func NewSigner(privateKey *PrivateKey, _ internalapi.Token) (tink.Signer, error) {
return &signer{
privateKey: ed25519.NewKeyFromSeed(privateKey.PrivateKeyBytes().Data(insecuresecretdataaccess.Token{})),
prefix: privateKey.OutputPrefix(),
variant: privateKey.publicKey.params.Variant(),
}, nil
}
// Sign computes a signature for the given data.
//
// If the key has prefix, the signature will be prefixed with the output
// prefix.
func (e *signer) Sign(data []byte) ([]byte, error) {
messageToSign := data
if e.variant == VariantLegacy {
messageToSign = slices.Concat(data, []byte{0})
}
r := ed25519.Sign(e.privateKey, messageToSign)
if len(r) != ed25519.SignatureSize {
return nil, fmt.Errorf("ed25519: invalid signature")
}
return slices.Concat(e.prefix, r), nil
}
func signerConstructor(key key.Key) (any, error) {
that, ok := key.(*PrivateKey)
if !ok {
return nil, fmt.Errorf("key is not a *ed25519.PrivateKey")
}
return NewSigner(that, internalapi.Token{})
}
|
