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
|
// Copyright 2021 Google Inc.
//
// 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 attest
import (
"crypto"
"crypto/ecdsa"
"crypto/rsa"
"fmt"
"io"
)
type key interface {
close(tpmBase) error
marshal() ([]byte, error)
certificationParameters() CertificationParameters
sign(tpmBase, []byte, crypto.PublicKey, crypto.SignerOpts) ([]byte, error)
decrypt(tpmBase, []byte) ([]byte, error)
blobs() ([]byte, []byte, error)
}
// Key represents a key which can be used for signing and decrypting
// outside-TPM objects.
type Key struct {
key key
pub crypto.PublicKey
tpm tpmBase
}
// signer implements crypto.Signer returned by Key.Private().
type signer struct {
key key
pub crypto.PublicKey
tpm tpmBase
}
// Sign signs digest with the TPM-stored private signing key.
func (s *signer) Sign(r io.Reader, digest []byte, opts crypto.SignerOpts) ([]byte, error) {
return s.key.sign(s.tpm, digest, s.pub, opts)
}
// Public returns the public key corresponding to the private signing key.
func (s *signer) Public() crypto.PublicKey {
return s.pub
}
// Algorithm indicates an asymmetric algorithm to be used.
type Algorithm string
// Algorithm types supported.
const (
ECDSA Algorithm = "ECDSA"
RSA Algorithm = "RSA"
)
// KeyConfig encapsulates parameters for minting keys.
type KeyConfig struct {
// Algorithm to be used, either RSA or ECDSA.
Algorithm Algorithm
// Size is used to specify the bit size of the key or elliptic curve. For
// example, '256' is used to specify curve P-256.
Size int
// Parent describes the Storage Root Key that will be used as a parent.
// If nil, the default SRK (i.e. RSA with handle 0x81000001) is assumed.
// Supported only by TPM 2.0 on Linux.
Parent *ParentKeyConfig
}
// defaultConfig is used when no other configuration is specified.
var defaultConfig = &KeyConfig{
Algorithm: ECDSA,
Size: 256,
}
// Public returns the public key corresponding to the private key.
func (k *Key) Public() crypto.PublicKey {
return k.pub
}
// Private returns an object allowing to use the TPM-backed private key.
// For now it implements only crypto.Signer.
func (k *Key) Private(pub crypto.PublicKey) (crypto.PrivateKey, error) {
switch pub.(type) {
case *rsa.PublicKey:
if _, ok := k.pub.(*rsa.PublicKey); !ok {
return nil, fmt.Errorf("incompatible public key types: %T != %T", pub, k.pub)
}
case *ecdsa.PublicKey:
if _, ok := k.pub.(*ecdsa.PublicKey); !ok {
return nil, fmt.Errorf("incompatible public key types: %T != %T", pub, k.pub)
}
default:
return nil, fmt.Errorf("unsupported public key type: %T", pub)
}
return &signer{k.key, k.pub, k.tpm}, nil
}
// Close unloads the key from the system.
func (k *Key) Close() error {
return k.key.close(k.tpm)
}
// Marshal encodes the key in a format that can be loaded with tpm.LoadKey().
// This method exists to allow consumers to store the key persistently and load
// it as a later time. Users SHOULD NOT attempt to interpret or extract values
// from this blob.
func (k *Key) Marshal() ([]byte, error) {
return k.key.marshal()
}
// CertificationParameters returns information about the key required to
// verify key certification.
func (k *Key) CertificationParameters() CertificationParameters {
return k.key.certificationParameters()
}
// Blobs returns public and private blobs to be used by tpm2.Load().
func (k *Key) Blobs() (pub, priv []byte, err error) {
return k.key.blobs()
}
|
