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
|
// Copyright 2016 Google LLC. All Rights Reserved.
//
// 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 tls
import (
"crypto"
"crypto/dsa" //nolint:staticcheck
"crypto/ecdsa"
_ "crypto/md5" // For registration side-effect
"crypto/rand"
"crypto/rsa"
_ "crypto/sha1" // For registration side-effect
_ "crypto/sha256" // For registration side-effect
_ "crypto/sha512" // For registration side-effect
"errors"
"fmt"
"log"
"math/big"
"github.com/google/certificate-transparency-go/asn1"
)
type dsaSig struct {
R, S *big.Int
}
func generateHash(algo HashAlgorithm, data []byte) ([]byte, crypto.Hash, error) {
var hashType crypto.Hash
switch algo {
case MD5:
hashType = crypto.MD5
case SHA1:
hashType = crypto.SHA1
case SHA224:
hashType = crypto.SHA224
case SHA256:
hashType = crypto.SHA256
case SHA384:
hashType = crypto.SHA384
case SHA512:
hashType = crypto.SHA512
default:
return nil, hashType, fmt.Errorf("unsupported Algorithm.Hash in signature: %v", algo)
}
hasher := hashType.New()
if _, err := hasher.Write(data); err != nil {
return nil, hashType, fmt.Errorf("failed to write to hasher: %v", err)
}
return hasher.Sum([]byte{}), hashType, nil
}
// VerifySignature verifies that the passed in signature over data was created by the given PublicKey.
func VerifySignature(pubKey crypto.PublicKey, data []byte, sig DigitallySigned) error {
hash, hashType, err := generateHash(sig.Algorithm.Hash, data)
if err != nil {
return err
}
switch sig.Algorithm.Signature {
case RSA:
rsaKey, ok := pubKey.(*rsa.PublicKey)
if !ok {
return fmt.Errorf("cannot verify RSA signature with %T key", pubKey)
}
if err := rsa.VerifyPKCS1v15(rsaKey, hashType, hash, sig.Signature); err != nil {
return fmt.Errorf("failed to verify rsa signature: %v", err)
}
case DSA:
dsaKey, ok := pubKey.(*dsa.PublicKey)
if !ok {
return fmt.Errorf("cannot verify DSA signature with %T key", pubKey)
}
var dsaSig dsaSig
rest, err := asn1.Unmarshal(sig.Signature, &dsaSig)
if err != nil {
return fmt.Errorf("failed to unmarshal DSA signature: %v", err)
}
if len(rest) != 0 {
log.Printf("Garbage following signature %q", rest)
}
if dsaSig.R.Sign() <= 0 || dsaSig.S.Sign() <= 0 {
return errors.New("DSA signature contained zero or negative values")
}
if !dsa.Verify(dsaKey, hash, dsaSig.R, dsaSig.S) {
return errors.New("failed to verify DSA signature")
}
case ECDSA:
ecdsaKey, ok := pubKey.(*ecdsa.PublicKey)
if !ok {
return fmt.Errorf("cannot verify ECDSA signature with %T key", pubKey)
}
var ecdsaSig dsaSig
rest, err := asn1.Unmarshal(sig.Signature, &ecdsaSig)
if err != nil {
return fmt.Errorf("failed to unmarshal ECDSA signature: %v", err)
}
if len(rest) != 0 {
log.Printf("Garbage following signature %q", rest)
}
if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
return errors.New("ECDSA signature contained zero or negative values")
}
if !ecdsa.Verify(ecdsaKey, hash, ecdsaSig.R, ecdsaSig.S) {
return errors.New("failed to verify ECDSA signature")
}
default:
return fmt.Errorf("unsupported Algorithm.Signature in signature: %v", sig.Algorithm.Hash)
}
return nil
}
// CreateSignature builds a signature over the given data using the specified hash algorithm and private key.
func CreateSignature(privKey crypto.PrivateKey, hashAlgo HashAlgorithm, data []byte) (DigitallySigned, error) {
var sig DigitallySigned
sig.Algorithm.Hash = hashAlgo
hash, hashType, err := generateHash(sig.Algorithm.Hash, data)
if err != nil {
return sig, err
}
switch privKey := privKey.(type) {
case rsa.PrivateKey:
sig.Algorithm.Signature = RSA
sig.Signature, err = rsa.SignPKCS1v15(rand.Reader, &privKey, hashType, hash)
return sig, err
case ecdsa.PrivateKey:
sig.Algorithm.Signature = ECDSA
var ecdsaSig dsaSig
ecdsaSig.R, ecdsaSig.S, err = ecdsa.Sign(rand.Reader, &privKey, hash)
if err != nil {
return sig, err
}
sig.Signature, err = asn1.Marshal(ecdsaSig)
return sig, err
default:
return sig, fmt.Errorf("unsupported private key type %T", privKey)
}
}
|
